diff --git a/src/Drupal/Driver/Alias/RolesAlias.php b/src/Drupal/Driver/Alias/RolesAlias.php
index f249e41c..24c3218d 100644
--- a/src/Drupal/Driver/Alias/RolesAlias.php
+++ b/src/Drupal/Driver/Alias/RolesAlias.php
@@ -63,6 +63,13 @@ public function applyAfterCreate(EntityStubInterface $stub, object $entity): voi
     }
 
     foreach ($roles as $role) {
+      // EntityReferenceHandler expands 'roles' into records like
+      // '['target_id' => 'editor']'. Unwrap that here so the alias can
+      // operate on the same role name the caller supplied originally.
+      if (is_array($role) && array_key_exists('target_id', $role)) {
+        $role = $role['target_id'];
+      }
+
       if (!is_scalar($role) && !$role instanceof \Stringable) {
         throw new CreationAliasResolutionException("Cannot assign role because one of the 'roles' entries is not a scalar or stringable value.");
       }
diff --git a/src/Drupal/Driver/Core/Alias/AuthorAlias.php b/src/Drupal/Driver/Core/Alias/AuthorAlias.php
index 80f960eb..88b063a5 100644
--- a/src/Drupal/Driver/Core/Alias/AuthorAlias.php
+++ b/src/Drupal/Driver/Core/Alias/AuthorAlias.php
@@ -82,7 +82,15 @@ public function applyToStub(EntityStubInterface $stub): void {
       throw new CreationAliasResolutionException(sprintf("Cannot create node because the 'author' lookup returned an object without an 'id()' method while resolving '%s'.", $name));
     }
 
-    $stub->setValue('uid', $user->id());
+    $resolved_uid = $user->id();
+
+    if (!is_numeric($resolved_uid) || (int) $resolved_uid <= 0) {
+      throw new CreationAliasResolutionException(sprintf("Cannot create node because the user resolved from 'author' = '%s' has an invalid id.", $name));
+    }
+
+    // Cast to int so the downstream entity-reference handler treats the
+    // value as a pre-resolved id and skips its own validation query.
+    $stub->setValue('uid', (int) $resolved_uid);
     $stub->removeValue('author');
   }
 
diff --git a/src/Drupal/Driver/Core/Alias/ParentTermAlias.php b/src/Drupal/Driver/Core/Alias/ParentTermAlias.php
index ca442575..1180e887 100644
--- a/src/Drupal/Driver/Core/Alias/ParentTermAlias.php
+++ b/src/Drupal/Driver/Core/Alias/ParentTermAlias.php
@@ -114,7 +114,13 @@ public function applyToStub(EntityStubInterface $stub): void {
       throw new CreationAliasResolutionException(sprintf("Cannot create term because parent term '%s' does not exist in vocabulary '%s'.", $parent_name, $vid));
     }
 
-    $stub->setValue('parent', $tid);
+    if (!is_numeric($tid) || (int) $tid <= 0) {
+      throw new CreationAliasResolutionException(sprintf("Cannot resolve parent term '%s' in vocabulary '%s' because the lookup returned an invalid tid.", $parent_name, $vid));
+    }
+
+    // Cast to int so the downstream entity-reference handler treats the
+    // value as a pre-resolved tid and skips its own validation query.
+    $stub->setValue('parent', (int) $tid);
   }
 
 }
diff --git a/src/Drupal/Driver/Core/Field/AbstractHandler.php b/src/Drupal/Driver/Core/Field/AbstractHandler.php
index 24e9dbad..ff362e44 100644
--- a/src/Drupal/Driver/Core/Field/AbstractHandler.php
+++ b/src/Drupal/Driver/Core/Field/AbstractHandler.php
@@ -12,6 +12,7 @@
  * Base class for field handlers.
  */
 abstract class AbstractHandler implements FieldHandlerInterface {
+
   /**
    * Field storage definition.
    */
@@ -25,13 +26,9 @@ abstract class AbstractHandler implements FieldHandlerInterface {
   /**
    * Main property name of the field's storage definition.
    *
-   * Cached once at construction so 'normalise()' and subclass 'expand()'
-   * methods do not have to look it up on every call. Resolves to the
-   * column key that a bare scalar maps to ('target_id' for image/file/
-   * entity_reference, 'value' for datetime/boolean/list/text, 'uri' for
-   * link, etc.). NULL for field types without a single main column (e.g.
-   * 'address', 'name'); those handlers must override 'normalise()' or
-   * 'expand()' to interpret records themselves.
+   * NULL for field types without a single main column (e.g. 'address',
+   * 'name'); those handlers must override 'normalise()' to interpret
+   * records themselves.
    */
   protected ?string $mainProperty = NULL;
 
@@ -81,12 +78,14 @@ public function __construct(EntityStubInterface $stub, string $entity_type, stri
   }
 
   /**
-   * Normalises loose handler input into a canonical list of records.
-   *
-   * Consumers should not have to know whether a field is single- or
-   * multi-column; this method accepts any of the natural shapes a caller
-   * is likely to produce and returns a uniform 'array<int, array<string,
-   * mixed>>' that 'expand()' implementations can iterate without sniffing.
+   * {@inheritdoc}
+   */
+  final public function expand(mixed $values): array {
+    return $this->doExpand($this->normalise($values));
+  }
+
+  /**
+   * Folds loose input into a canonical list of records.
    *
    * Recognised input shapes:
    *   - Bare scalar -> wrapped as a single record using the main property.
@@ -95,19 +94,15 @@ public function __construct(EntityStubInterface $stub, string $entity_type, stri
    *   - List of records -> returned unchanged.
    *   - Mixed list of scalars and records -> scalars wrapped, records kept.
    *
-   * The main property name (the column a bare scalar maps to) is pulled
-   * from the field's storage definition - 'target_id' for image/file/
-   * entity_reference, 'value' for datetime/boolean/list/text, 'uri' for
-   * link, etc. Subclasses with custom shorthand (e.g. 'NameHandler's
-   * 'Family, Given' string, 'AddressHandler's first-visible-field
-   * shorthand) should override this method and call 'parent::normalise()'
-   * for the residual cases they do not handle themselves.
+   * Subclasses with custom shorthand override this method and may call
+   * 'parent::normalise()' for the residual shapes they do not handle
+   * themselves.
    *
    * @param mixed $values
    *   Whatever shape the caller produced.
    *
    * @return array<int, array<string, mixed>>
-   *   A canonical list of records.
+   *   Canonical list of records.
    */
   protected function normalise(mixed $values): array {
     if ($this->mainProperty === NULL) {
@@ -172,4 +167,15 @@ protected function normalise(mixed $values): array {
     return $records;
   }
 
+  /**
+   * Transforms canonical records into the storage shape.
+   *
+   * @param array<int, array<string, mixed>> $records
+   *   Canonical list of records.
+   *
+   * @return array<int|string, mixed>
+   *   Field values in the format expected by Drupal's entity storage.
+   */
+  abstract protected function doExpand(array $records): array;
+
 }
diff --git a/src/Drupal/Driver/Core/Field/AddressHandler.php b/src/Drupal/Driver/Core/Field/AddressHandler.php
index 6c0689d4..e835352b 100644
--- a/src/Drupal/Driver/Core/Field/AddressHandler.php
+++ b/src/Drupal/Driver/Core/Field/AddressHandler.php
@@ -5,22 +5,67 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Address field handler for Drupal 8.
+ * Field handler for 'address' fields.
  */
 class AddressHandler extends AbstractHandler {
 
   /**
    * {@inheritdoc}
    */
-  public function expand($values): array {
+  protected function normalise(mixed $values): array {
+    if ($values === []) {
+      return [];
+    }
+
     $visible_fields = $this->getVisibleAddressFields();
-    $result = [];
+
+    if (is_string($values)) {
+      return [$this->normaliseDelta($values, $visible_fields)];
+    }
+
+    if (!is_array($values)) {
+      throw new \InvalidArgumentException(sprintf('Address field value must be a string or array. Got %s.', get_debug_type($values)));
+    }
+
+    // A top-level list of scalars is a single positional address (the
+    // visible-field positions), not a multi-delta list. Only a list whose
+    // first element is an array iterates as multi-delta.
+    $is_list_of_records = array_is_list($values) && is_array($values[0] ?? NULL);
+
+    if (!$is_list_of_records) {
+      return [$this->normaliseDelta($values, $visible_fields)];
+    }
+
+    $records = [];
 
     foreach ($values as $value) {
-      $result[] = $this->normaliseDelta($value, $visible_fields);
+      if (!is_array($value) && !is_string($value)) {
+        throw new \InvalidArgumentException(sprintf('Address field delta must be a string or array. Got %s.', get_debug_type($value)));
+      }
+
+      $records[] = $this->normaliseDelta($value, $visible_fields);
     }
 
-    return $result;
+    return $records;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function doExpand(array $records): array {
+    // 'available_countries' is empty when the field accepts every country;
+    // 'reset([])' returns FALSE, which would land a boolean in storage.
+    // Leave 'country_code' unset in that case so the field's own default
+    // wins instead.
+    $available = $this->fieldConfig->getSettings()['available_countries'] ?? [];
+
+    foreach ($records as &$record) {
+      if (!isset($record['country_code']) && $available !== []) {
+        $record['country_code'] = reset($available);
+      }
+    }
+
+    return $records;
   }
 
   /**
@@ -64,7 +109,7 @@ protected function getVisibleAddressFields(): array {
   }
 
   /**
-   * Normalises a single address delta into a keyed array.
+   * Folds one address value into a keyed sub-field array.
    *
    * @param mixed $value
    *   A single address value (string or array).
@@ -100,10 +145,6 @@ protected function normaliseDelta(mixed $value, array $visible_fields): array {
       $position++;
     }
 
-    if (!isset($normalised['country_code'])) {
-      $normalised['country_code'] = reset($this->fieldConfig->getSettings()['available_countries']);
-    }
-
     return $normalised;
   }
 
diff --git a/src/Drupal/Driver/Core/Field/BooleanHandler.php b/src/Drupal/Driver/Core/Field/BooleanHandler.php
index 8ad3a68c..bf3ffad2 100644
--- a/src/Drupal/Driver/Core/Field/BooleanHandler.php
+++ b/src/Drupal/Driver/Core/Field/BooleanHandler.php
@@ -5,42 +5,22 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Field handler for the 'boolean' field type.
- *
- * Scenarios authored against a BDD driver read naturally when boolean columns
- * carry human words ('Yes', 'Published') rather than the raw 1/0 the Drupal
- * field API stores. This handler resolves an incoming value in two stages:
- *
- *  1. The field's own 'on_label' / 'off_label' settings, compared
- *     case-insensitively. These are the labels the site builder configured;
- *     they already reflect the site's active language, so translated sites
- *     get translation matching for free.
- *  2. A canonical allow-list via 'filter_var(FILTER_VALIDATE_BOOLEAN)':
- *     '1', 'true', 'on', 'yes' map to 1; '0', 'false', 'off', 'no', '' map
- *     to 0. Case-insensitive.
- *
- * A value that matches neither throws a descriptive 'RuntimeException' listing
- * both the field-specific labels and the canonical set, so scenario authors
- * get an actionable error instead of a silent coercion to FALSE.
- *
- * Subclasses in a 'Core{N}\Field\' tree can override 'resolveBoolean()' to
- * extend the mapping (e.g. site-specific synonyms) without reimplementing the
- * per-delta loop.
+ * Field handler for 'boolean' fields.
  */
 class BooleanHandler extends AbstractHandler {
 
   /**
    * {@inheritdoc}
    */
-  public function expand(mixed $values): array {
+  protected function doExpand(array $records): array {
     $settings = $this->fieldConfig->getSettings();
     $on_label = (string) ($settings['on_label'] ?? '');
     $off_label = (string) ($settings['off_label'] ?? '');
 
     $resolved = [];
 
-    foreach ((array) $values as $value) {
-      $resolved[] = $this->resolveBoolean((string) $value, $on_label, $off_label);
+    foreach ($records as $record) {
+      $resolved[] = $this->resolveBoolean((string) $record['value'], $on_label, $off_label);
     }
 
     return $resolved;
diff --git a/src/Drupal/Driver/Core/Field/DaterangeHandler.php b/src/Drupal/Driver/Core/Field/DaterangeHandler.php
index 9e0994f6..c40402a5 100644
--- a/src/Drupal/Driver/Core/Field/DaterangeHandler.php
+++ b/src/Drupal/Driver/Core/Field/DaterangeHandler.php
@@ -7,23 +7,58 @@
 use Drupal\datetime\Plugin\Field\FieldType\DateTimeItemInterface;
 
 /**
- * Daterange field handler for Drupal 8.
- *
- * Extends DatetimeHandler to reuse date formatting logic.
+ * Field handler for 'daterange' fields.
  */
 class DaterangeHandler extends DatetimeHandler {
 
   /**
    * {@inheritdoc}
    */
-  public function expand($values): array {
+  protected function normalise(mixed $values): array {
+    if (!is_array($values) || $values === []) {
+      return [];
+    }
+
+    // A top-level positional pair like ['start', 'end'] is itself a list,
+    // so iterating directly would treat each scalar as its own delta and
+    // reject it. Only a list whose first element is an array is treated
+    // as a multi-delta list.
+    $is_list_of_records = array_is_list($values) && is_array($values[0] ?? NULL);
+
+    if (!$is_list_of_records) {
+      $values = [$values];
+    }
+
+    $records = [];
+
+    foreach ($values as $value) {
+      if (!is_array($value)) {
+        throw new \InvalidArgumentException(sprintf(
+          'Daterange field record must be an array (positional [start, end] or keyed value/end_value). Got %s.',
+          get_debug_type($value),
+        ));
+      }
+
+      $records[] = [
+        'value' => $value['value'] ?? $value[0] ?? NULL,
+        'end_value' => $value['end_value'] ?? $value[1] ?? NULL,
+      ];
+    }
+
+    return $records;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function doExpand(array $records): array {
     $site_timezone = new \DateTimeZone(\Drupal::config('system.date')->get('timezone.default') ?: 'UTC');
     $storage_timezone = new \DateTimeZone(DateTimeItemInterface::STORAGE_TIMEZONE);
     $result = [];
 
-    foreach ($values as $value) {
-      $start = $value['value'] ?? $value[0] ?? NULL;
-      $end = $value['end_value'] ?? $value[1] ?? NULL;
+    foreach ($records as $record) {
+      $start = $record['value'];
+      $end = $record['end_value'];
 
       $result[] = [
         'value' => $start ? $this->formatDateValue($start, $site_timezone, $storage_timezone) : NULL,
diff --git a/src/Drupal/Driver/Core/Field/DatetimeHandler.php b/src/Drupal/Driver/Core/Field/DatetimeHandler.php
index ea62b7c2..53336aac 100644
--- a/src/Drupal/Driver/Core/Field/DatetimeHandler.php
+++ b/src/Drupal/Driver/Core/Field/DatetimeHandler.php
@@ -9,26 +9,19 @@
 use Drupal\datetime\Plugin\Field\FieldType\DateTimeItemInterface;
 
 /**
- * Datetime field handler for Drupal 8.
+ * Field handler for 'datetime' fields.
  */
 class DatetimeHandler extends AbstractHandler {
 
   /**
    * {@inheritdoc}
-   *
-   * Accepts whatever shape the caller naturally has: a bare date string,
-   * a list of date strings, a single record, or a list of records.
-   * 'normalise()' folds all of those into a canonical list of records
-   * before iteration. Returns a uniform list of records with 'value'
-   * formatted for storage.
    */
-  public function expand($values): array {
+  protected function doExpand(array $records): array {
     // Fresh Drupal installs leave system.date:timezone.default NULL until the
     // installer writes a value; fall back to UTC so the handler never passes
     // NULL to DateTimeZone.
     $site_timezone = new \DateTimeZone(\Drupal::config('system.date')->get('timezone.default') ?: 'UTC');
     $storage_timezone = new \DateTimeZone(DateTimeItemInterface::STORAGE_TIMEZONE);
-    $records = $this->normalise($values);
     $formatted = [];
 
     foreach ($records as $record) {
diff --git a/src/Drupal/Driver/Core/Field/DefaultHandler.php b/src/Drupal/Driver/Core/Field/DefaultHandler.php
index b6bcbcc6..13ec88ff 100644
--- a/src/Drupal/Driver/Core/Field/DefaultHandler.php
+++ b/src/Drupal/Driver/Core/Field/DefaultHandler.php
@@ -16,7 +16,7 @@ class DefaultHandler extends AbstractHandler {
   /**
    * {@inheritdoc}
    */
-  public function expand(mixed $values): array {
+  protected function doExpand(array $records): array {
     $columns = $this->fieldInfo->getColumns();
 
     if (count($columns) !== 1 || !array_key_exists('value', $columns)) {
@@ -31,7 +31,7 @@ public function expand(mixed $values): array {
       ));
     }
 
-    return (array) $values;
+    return $records;
   }
 
 }
diff --git a/src/Drupal/Driver/Core/Field/EmbridgeAssetItemHandler.php b/src/Drupal/Driver/Core/Field/EmbridgeAssetItemHandler.php
index 7f5c3960..e095a8eb 100644
--- a/src/Drupal/Driver/Core/Field/EmbridgeAssetItemHandler.php
+++ b/src/Drupal/Driver/Core/Field/EmbridgeAssetItemHandler.php
@@ -5,7 +5,7 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Embridge Asset Item field handler for Drupal 8.
+ * Field handler for 'embridge_asset_item' fields (Embridge contrib).
  */
 class EmbridgeAssetItemHandler extends EntityReferenceHandler {
 
diff --git a/src/Drupal/Driver/Core/Field/EntityReferenceHandler.php b/src/Drupal/Driver/Core/Field/EntityReferenceHandler.php
index 18d36908..7e59ca8c 100644
--- a/src/Drupal/Driver/Core/Field/EntityReferenceHandler.php
+++ b/src/Drupal/Driver/Core/Field/EntityReferenceHandler.php
@@ -5,43 +5,50 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Entity Reference field handler for Drupal 8.
+ * Field handler for 'entity_reference' fields.
  */
 class EntityReferenceHandler extends AbstractHandler {
 
   /**
    * {@inheritdoc}
    */
-  public function expand($values): array {
+  protected function doExpand(array $records): array {
     $entity_type_id = $this->fieldInfo->getSetting('target_type');
     $entity_definition = \Drupal::entityTypeManager()->getDefinition($entity_type_id);
     $id_key = $entity_definition->getKey('id');
 
     // User entities return FALSE for getKey('label'), so use 'name' directly.
     $label_key = $entity_type_id !== 'user' ? $entity_definition->getKey('label') : 'name';
-    $main_property = $this->fieldInfo->getMainPropertyName();
 
-    // Determine target bundle restrictions.
     $target_bundles = $this->getTargetBundles();
     $target_bundle_key = $target_bundles ? $entity_definition->getKey('bundle') : NULL;
 
     $resolved = [];
 
-    foreach ((array) $values as $value) {
-      // A delta may be a scalar (label or id) OR an associative array carrying
-      // the main property plus additional item columns (e.g. 'display' on file
-      // references or 'target_revision_id' on entity_reference_revisions).
-      // When the main property is present, use its value as the lookup label
-      // and preserve the rest of the array so those extras round-trip through
-      // to storage.
-      $has_extras = is_string($main_property) && is_array($value) && array_key_exists($main_property, $value);
-      $lookup = $has_extras ? $value[$main_property] : $value;
+    foreach ($records as $record) {
+      if (!array_key_exists($this->mainProperty, $record)) {
+        throw new \InvalidArgumentException(sprintf('Entity reference record is missing the main property "%s".', $this->mainProperty));
+      }
+
+      $lookup = $record[$this->mainProperty];
+
+      // Already-resolved integer ids (caller-supplied or alias-resolved)
+      // bypass the entity-storage round-trip; only string labels still
+      // need a lookup.
+      if (is_int($lookup)) {
+        $resolved[] = $record;
+        continue;
+      }
 
       $query = \Drupal::entityQuery($entity_type_id);
       $query->accessCheck(FALSE);
 
       if ($label_key) {
-        $is_numeric_id = is_int($lookup) || (is_string($lookup) && ctype_digit($lookup));
+        // A numeric-string lookup is ambiguous - the caller may be passing
+        // an entity id that Drupal serialised as a string, or a label that
+        // happens to be digits. Match either side with an OR-group so the
+        // entity layer's first hit wins.
+        $is_numeric_id = is_string($lookup) && ctype_digit($lookup);
         $or = $query->orConditionGroup();
 
         if ($is_numeric_id) {
@@ -65,27 +72,20 @@ public function expand($values): array {
         throw new \Exception(sprintf("No entity '%s' of type '%s' exists.", $lookup, $entity_type_id));
       }
 
-      $resolved_id = array_shift($entities);
-
-      if ($has_extras) {
-        $value[$main_property] = $resolved_id;
-        $resolved[] = $value;
-      }
-      else {
-        $resolved[] = $resolved_id;
-      }
+      $record[$this->mainProperty] = array_shift($entities);
+      $resolved[] = $record;
     }
 
     return $resolved;
   }
 
   /**
-   * Retrieves bundles for which the field is configured to reference.
+   * Returns bundle restrictions configured on the field, or NULL.
    *
-   * @return mixed
-   *   Array of bundle names, or NULL if not able to determine bundles.
+   * @return array<int|string, string>|null
+   *   Bundle names the field may target, or NULL when unrestricted.
    */
-  protected function getTargetBundles(): mixed {
+  protected function getTargetBundles(): ?array {
     $settings = $this->fieldConfig->getSettings();
 
     if (!empty($settings['handler_settings']['target_bundles'])) {
diff --git a/src/Drupal/Driver/Core/Field/EntityReferenceRevisionsHandler.php b/src/Drupal/Driver/Core/Field/EntityReferenceRevisionsHandler.php
index 6da80f6c..3accaeba 100644
--- a/src/Drupal/Driver/Core/Field/EntityReferenceRevisionsHandler.php
+++ b/src/Drupal/Driver/Core/Field/EntityReferenceRevisionsHandler.php
@@ -7,26 +7,19 @@
 use Drupal\Core\Entity\RevisionableInterface;
 
 /**
- * Entity Reference Revisions field handler.
- *
- * Handles the 'entity_reference_revisions' field type (used by Paragraphs
- * among others). Resolves targets the same way 'EntityReferenceHandler' does
- * and additionally populates 'target_revision_id' with the current revision
- * id of each resolved target, producing storage entries shaped like
- * '['target_id' => X, 'target_revision_id' => Y]'.
+ * Field handler for 'entity_reference_revisions' fields (Paragraphs et al).
  */
 class EntityReferenceRevisionsHandler extends AbstractHandler {
 
   /**
    * {@inheritdoc}
    */
-  public function expand($values): array {
+  protected function doExpand(array $records): array {
     $entity_type_id = $this->fieldInfo->getSetting('target_type');
     $entity_type_manager = \Drupal::entityTypeManager();
     $entity_definition = $entity_type_manager->getDefinition($entity_type_id);
     $id_key = $entity_definition->getKey('id');
     $label_key = $entity_type_id !== 'user' ? $entity_definition->getKey('label') : 'name';
-    $main_property = $this->fieldInfo->getMainPropertyName();
 
     $target_bundles = $this->getTargetBundles();
     $target_bundle_key = $target_bundles ? $entity_definition->getKey('bundle') : NULL;
@@ -34,67 +27,73 @@ public function expand($values): array {
     $storage = $entity_type_manager->getStorage($entity_type_id);
     $resolved = [];
 
-    foreach ((array) $values as $value) {
-      $has_extras = is_string($main_property) && is_array($value) && array_key_exists($main_property, $value);
-      $lookup = $has_extras ? $value[$main_property] : $value;
+    foreach ($records as $record) {
+      if (!array_key_exists($this->mainProperty, $record)) {
+        throw new \InvalidArgumentException(sprintf('Entity reference revisions record is missing the main property "%s".', $this->mainProperty));
+      }
+
+      $lookup = $record[$this->mainProperty];
+
+      if (is_int($lookup)) {
+        $resolved_id = $lookup;
+      }
+      else {
+        $query = \Drupal::entityQuery($entity_type_id);
+        $query->accessCheck(FALSE);
 
-      $query = \Drupal::entityQuery($entity_type_id);
-      $query->accessCheck(FALSE);
+        if ($label_key) {
+          $is_numeric_id = is_string($lookup) && ctype_digit($lookup);
+          $or = $query->orConditionGroup();
 
-      if ($label_key) {
-        $is_numeric_id = is_int($lookup) || (is_string($lookup) && ctype_digit($lookup));
-        $or = $query->orConditionGroup();
+          if ($is_numeric_id) {
+            $or->condition($id_key, (int) $lookup);
+          }
 
-        if ($is_numeric_id) {
-          $or->condition($id_key, (int) $lookup);
+          $or->condition($label_key, $lookup);
+          $query->condition($or);
+        }
+        else {
+          $query->condition($id_key, $lookup);
         }
 
-        $or->condition($label_key, $lookup);
-        $query->condition($or);
-      }
-      else {
-        $query->condition($id_key, $lookup);
-      }
+        if ($target_bundles && $target_bundle_key) {
+          $query->condition($target_bundle_key, $target_bundles, 'IN');
+        }
 
-      if ($target_bundles && $target_bundle_key) {
-        $query->condition($target_bundle_key, $target_bundles, 'IN');
-      }
+        $entities = $query->execute();
 
-      $entities = $query->execute();
+        if (!$entities) {
+          throw new \Exception(sprintf("No entity '%s' of type '%s' exists.", $lookup, $entity_type_id));
+        }
 
-      if (!$entities) {
-        throw new \Exception(sprintf("No entity '%s' of type '%s' exists.", $lookup, $entity_type_id));
+        $resolved_id = array_shift($entities);
       }
 
-      $resolved_id = array_shift($entities);
       $target = $storage->load($resolved_id);
-      $revision_id = $target instanceof RevisionableInterface ? $target->getRevisionId() : NULL;
 
-      if ($has_extras) {
-        $value[$main_property] = $resolved_id;
-        if ($revision_id !== NULL && !array_key_exists('target_revision_id', $value)) {
-          $value['target_revision_id'] = $revision_id;
-        }
-        $resolved[] = $value;
+      if ($target === NULL) {
+        throw new \Exception(sprintf("Entity '%s' of type '%s' no longer exists.", $resolved_id, $entity_type_id));
       }
-      else {
-        $resolved[] = [
-          'target_id' => $resolved_id,
-          'target_revision_id' => $revision_id,
-        ];
+
+      $record[$this->mainProperty] = $resolved_id;
+
+      if (!array_key_exists('target_revision_id', $record)) {
+        $record['target_revision_id'] = $target instanceof RevisionableInterface ? $target->getRevisionId() : NULL;
       }
+
+      $resolved[] = $record;
     }
 
     return $resolved;
   }
 
   /**
-   * Retrieves bundles for which the field is configured to reference.
+   * Returns bundle restrictions configured on the field, or NULL.
    *
-   * @return mixed
-   *   Array of bundle names, or NULL if not able to determine bundles.
+   * @return array<int|string, string>|null
+   *   Bundle names the field may target, or NULL when unrestricted.
    */
-  protected function getTargetBundles(): mixed {
+  protected function getTargetBundles(): ?array {
     $settings = $this->fieldConfig->getSettings();
 
     if (!empty($settings['handler_settings']['target_bundles'])) {
diff --git a/src/Drupal/Driver/Core/Field/FieldHandlerInterface.php b/src/Drupal/Driver/Core/Field/FieldHandlerInterface.php
index e4e69b39..1118dc83 100644
--- a/src/Drupal/Driver/Core/Field/FieldHandlerInterface.php
+++ b/src/Drupal/Driver/Core/Field/FieldHandlerInterface.php
@@ -5,26 +5,18 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Interface for handling fields.
- *
- * Saving fields on entities is handled differently depending on the Drupal
- * version. This interface translates abstract field data into the format that
- * is expected by the different storage handlers.
+ * Field handler contract.
  */
 interface FieldHandlerInterface {
 
   /**
-   * Expand abstract field values so they can be saved on the entity.
-   *
-   * This method takes care of the different ways that field data is saved on
-   * entities in different versions of Drupal.
+   * Transforms loose field input into the storage shape.
    *
    * @param mixed $values
-   *   A single value or an array of field values to save on the entity.
+   *   Whatever shape the caller produced.
    *
    * @return array<int|string, mixed>
-   *   An array of field values in the format expected by the entity storage
-   *   handlers in the driver's version of Drupal.
+   *   Field values in the format expected by Drupal's entity storage.
    */
   public function expand(mixed $values): array;
 
diff --git a/src/Drupal/Driver/Core/Field/FileHandler.php b/src/Drupal/Driver/Core/Field/FileHandler.php
index ff0edd4c..3dce99ac 100644
--- a/src/Drupal/Driver/Core/Field/FileHandler.php
+++ b/src/Drupal/Driver/Core/Field/FileHandler.php
@@ -5,32 +5,54 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * File field handler for Drupal 8.
+ * Field handler for 'file' fields.
  */
 class FileHandler extends AbstractHandler {
 
   /**
    * {@inheritdoc}
    */
-  public function expand($values): array {
-    $files = [];
+  protected function normalise(mixed $values): array {
+    $records = parent::normalise($values);
+
+    foreach ($records as &$record) {
+      if ($record[$this->mainProperty] === NULL || $record[$this->mainProperty] === '') {
+        throw new \InvalidArgumentException(sprintf('%s field "%s" must not be NULL or empty.', $this->getFieldLabel(), $this->mainProperty));
+      }
+
+      $record[$this->mainProperty] = (string) $record[$this->mainProperty];
+    }
 
-    foreach ((array) $values as $value) {
-      $is_array = is_array($value);
-      $file_path = (string) ($is_array ? $value['target_id'] ?? $value[0] : $value);
+    return $records;
+  }
 
+  /**
+   * {@inheritdoc}
+   */
+  protected function doExpand(array $records): array {
+    $files = [];
+
+    foreach ($records as $record) {
+      $file_path = $record[$this->mainProperty];
       $file = $this->resolveExistingFile($file_path) ?? $this->uploadAndSave($file_path);
 
       $files[] = [
-        'target_id' => $file->id(),
-        'display' => $is_array ? ($value['display'] ?? 1) : 1,
-        'description' => $is_array ? ($value['description'] ?? '') : '',
+        $this->mainProperty => $file->id(),
+        'display' => $record['display'] ?? 1,
+        'description' => $record['description'] ?? '',
       ];
     }
 
     return $files;
   }
 
+  /**
+   * Human-readable label used in error messages.
+   */
+  protected function getFieldLabel(): string {
+    return 'File';
+  }
+
   /**
    * Returns a managed File addressed by URI or bare basename, or NULL.
    *
diff --git a/src/Drupal/Driver/Core/Field/ImageHandler.php b/src/Drupal/Driver/Core/Field/ImageHandler.php
index 19a5319f..78e739bd 100644
--- a/src/Drupal/Driver/Core/Field/ImageHandler.php
+++ b/src/Drupal/Driver/Core/Field/ImageHandler.php
@@ -5,36 +5,18 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Image field handler for Drupal 8.
- *
- * Extends FileHandler to inherit the resolve-existing-managed-file lookup
- * (by URI or bare basename) and the upload-and-save fallback. Overrides
- * expand() to return the image-specific shape ('target_id', 'alt', 'title').
+ * Field handler for 'image' fields.
  */
 class ImageHandler extends FileHandler {
 
   /**
    * {@inheritdoc}
-   *
-   * Accepts whatever shape the caller naturally has: a bare path, a list
-   * of paths, a single record, or a list of records. 'normalise()' folds
-   * all of those into a canonical list of records before iteration.
-   * Returns a uniform list of records with 'target_id' resolved to a
-   * File entity id.
    */
-  public function expand($values): array {
-    $records = $this->normalise($values);
+  protected function doExpand(array $records): array {
     $expanded = [];
 
     foreach ($records as $record) {
-      // normalise() already enforced that the main property key is on every
-      // record; here we additionally reject NULL/empty values because the
-      // file resolver and uploader need a real path/URI/basename.
-      if ($record[$this->mainProperty] === NULL || $record[$this->mainProperty] === '') {
-        throw new \InvalidArgumentException(sprintf('Image field "%s" must not be NULL or empty.', $this->mainProperty));
-      }
-
-      $file_path = (string) $record[$this->mainProperty];
+      $file_path = $record[$this->mainProperty];
       $file = $this->resolveExistingFile($file_path) ?? $this->uploadAndSave($file_path);
 
       $expanded[] = [
@@ -47,4 +29,11 @@ public function expand($values): array {
     return $expanded;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  protected function getFieldLabel(): string {
+    return 'Image';
+  }
+
 }
diff --git a/src/Drupal/Driver/Core/Field/LinkHandler.php b/src/Drupal/Driver/Core/Field/LinkHandler.php
index 37df28c4..6acd659a 100644
--- a/src/Drupal/Driver/Core/Field/LinkHandler.php
+++ b/src/Drupal/Driver/Core/Field/LinkHandler.php
@@ -5,36 +5,105 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Link field handler for Drupal 8.
+ * Field handler for 'link' fields.
  */
 class LinkHandler extends AbstractHandler {
 
   /**
    * {@inheritdoc}
    */
-  public function expand($values): array {
-    $links = [];
+  protected function normalise(mixed $values): array {
+    if (!is_array($values)) {
+      return [['uri' => $values]];
+    }
+
+    if ($values === []) {
+      return [];
+    }
+
+    // Reject top-level mixed positional/named keys so a single-keyed
+    // record cannot be confused with a list of positional ones.
+    $has_int_key = FALSE;
+    $has_string_key = FALSE;
+
+    foreach (array_keys($values) as $key) {
+      if (is_int($key)) {
+        $has_int_key = TRUE;
+      }
+      else {
+        $has_string_key = TRUE;
+      }
+    }
+
+    if ($has_int_key && $has_string_key) {
+      throw new \InvalidArgumentException(sprintf(
+        'Link field value cannot mix positional and named keys at the top level. Got keys: %s.',
+        implode(', ', array_keys($values)),
+      ));
+    }
+
+    if (!array_is_list($values)) {
+      $values = [$values];
+    }
+
+    $records = [];
 
     foreach ($values as $value) {
-      // Support URI-only string values.
-      if (is_string($value)) {
-        $value = ['uri' => $value];
+      if (!is_array($value)) {
+        $records[] = ['uri' => $value];
+        continue;
+      }
+
+      $record = [];
+
+      if (isset($value['title']) || array_key_exists(0, $value)) {
+        $record['title'] = $value['title'] ?? $value[0];
       }
 
-      // Support both named keys (title, uri, options) and numeric indices.
+      if (isset($value['uri']) || array_key_exists(1, $value)) {
+        $record['uri'] = $value['uri'] ?? $value[1];
+      }
+
+      if (isset($value['options']) || array_key_exists(2, $value)) {
+        $record['options'] = $value['options'] ?? $value[2];
+      }
+
+      if (!array_key_exists('uri', $record)) {
+        throw new \InvalidArgumentException(sprintf(
+          'Link field record must include a uri (named "uri" key or positional index 1). Got keys: %s.',
+          implode(', ', array_keys($value)) ?: '(none)',
+        ));
+      }
+
+      $records[] = $record;
+    }
+
+    return $records;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function doExpand(array $records): array {
+    $links = [];
+
+    foreach ($records as $record) {
       $link = array_filter([
-        'title' => $value['title'] ?? $value[0] ?? NULL,
-        'uri' => $value['uri'] ?? $value[1] ?? NULL,
+        'title' => $record['title'] ?? NULL,
+        'uri' => $record['uri'] ?? NULL,
         'options' => [],
       ], fn ($v): bool => $v !== NULL);
 
-      // 'options' is required to be an array, otherwise the utility class
-      // Drupal\Core\Utility\UnroutedUrlAssembler::assemble() will complain.
-      $options = $value['options'] ?? $value[2] ?? NULL;
+      // 'options' must be an array; UnroutedUrlAssembler::assemble()
+      // rejects string values. Accept query-string shorthand and parse it.
+      $options = $record['options'] ?? NULL;
 
-      if ($options) {
+      if (is_string($options) && $options !== '') {
         parse_str($options, $link['options']);
       }
+      elseif (is_array($options)) {
+        $link['options'] = $options;
+      }
 
       $links[] = $link;
     }
diff --git a/src/Drupal/Driver/Core/Field/ListFloatHandler.php b/src/Drupal/Driver/Core/Field/ListFloatHandler.php
index fd8c8008..8ce26fd8 100644
--- a/src/Drupal/Driver/Core/Field/ListFloatHandler.php
+++ b/src/Drupal/Driver/Core/Field/ListFloatHandler.php
@@ -5,6 +5,15 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Handler for ListFloat fields.
+ * Field handler for 'list_float' fields.
  */
-class ListFloatHandler extends ListHandlerBase {}
+class ListFloatHandler extends ListHandlerBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function castStorageKey(mixed $key): float {
+    return (float) $key;
+  }
+
+}
diff --git a/src/Drupal/Driver/Core/Field/ListHandlerBase.php b/src/Drupal/Driver/Core/Field/ListHandlerBase.php
index 4d3cb86d..5acd1cbc 100644
--- a/src/Drupal/Driver/Core/Field/ListHandlerBase.php
+++ b/src/Drupal/Driver/Core/Field/ListHandlerBase.php
@@ -5,30 +5,31 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Base class for List* field types.
- *
- * This allows use of allowed value labels rather than their storage value.
+ * Base class for 'list_*' field handlers.
  */
 abstract class ListHandlerBase extends AbstractHandler {
 
   /**
    * {@inheritdoc}
    */
-  public function expand(mixed $values): array {
+  protected function doExpand(array $records): array {
+    $allowed_values = $this->fieldInfo->getSetting('allowed_values');
     $return = [];
 
-    // Load allowed values from field storage.
-    $allowed_values = $this->fieldInfo->getSetting('allowed_values');
-    foreach ((array) $values as $value) {
-      // Determine if a label matching the value is found.
+    foreach ($records as $record) {
+      $value = $record['value'];
       $key = array_search($value, $allowed_values, TRUE);
-      if ($key !== FALSE) {
-        // Set the return to use the key instead of the value.
-        $return[] = $key;
-      }
+      $return[] = $key !== FALSE ? $this->castStorageKey($key) : $value;
     }
 
-    return $return ?: $values;
+    return $return;
+  }
+
+  /**
+   * Casts a resolved storage key to the field type's expected PHP type.
+   */
+  protected function castStorageKey(mixed $key): mixed {
+    return $key;
   }
 
 }
diff --git a/src/Drupal/Driver/Core/Field/NameHandler.php b/src/Drupal/Driver/Core/Field/NameHandler.php
index cf1b9e09..91fd3751 100644
--- a/src/Drupal/Driver/Core/Field/NameHandler.php
+++ b/src/Drupal/Driver/Core/Field/NameHandler.php
@@ -5,9 +5,9 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Name field handler for Drupal 8.
+ * Field handler for 'name' fields.
  *
- * Supports the Name module (https://www.drupal.org/project/name).
+ * @see https://www.drupal.org/project/name
  */
 class NameHandler extends AbstractHandler {
 
@@ -38,8 +38,21 @@ class NameHandler extends AbstractHandler {
   /**
    * {@inheritdoc}
    */
-  public function expand($values): array {
+  protected function normalise(mixed $values): array {
     $enabled = $this->getEnabledComponents();
+
+    if (is_string($values)) {
+      return [$this->normaliseString($values, $enabled)];
+    }
+
+    if (!is_array($values) || $values === []) {
+      return [];
+    }
+
+    if (!array_is_list($values)) {
+      return [$this->normaliseArray($values, $enabled)];
+    }
+
     $names = [];
 
     foreach ($values as $value) {
@@ -56,6 +69,13 @@ public function expand($values): array {
     return $names;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  protected function doExpand(array $records): array {
+    return $records;
+  }
+
   /**
    * Returns name components enabled on the field, in canonical order.
    *
diff --git a/src/Drupal/Driver/Core/Field/OgStandardReferenceHandler.php b/src/Drupal/Driver/Core/Field/OgStandardReferenceHandler.php
index 157c9c8a..b0fa18e3 100644
--- a/src/Drupal/Driver/Core/Field/OgStandardReferenceHandler.php
+++ b/src/Drupal/Driver/Core/Field/OgStandardReferenceHandler.php
@@ -5,7 +5,7 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Field handler for 'og_standard_reference' (Organic Groups) in Drupal 8.
+ * Field handler for 'og_standard_reference' fields (Organic Groups contrib).
  */
 class OgStandardReferenceHandler extends EntityReferenceHandler {
 }
diff --git a/src/Drupal/Driver/Core/Field/SmartdateHandler.php b/src/Drupal/Driver/Core/Field/SmartdateHandler.php
index f4537465..28f7977a 100644
--- a/src/Drupal/Driver/Core/Field/SmartdateHandler.php
+++ b/src/Drupal/Driver/Core/Field/SmartdateHandler.php
@@ -5,43 +5,61 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Smartdate field handler for the smart_date contrib module.
- *
- * Smart date fields store six columns: 'value' and 'end_value' as Unix
- * integer timestamps, 'duration' in whole minutes, 'rrule' and
- * 'rrule_index' for recurring events, and 'timezone' as a string. Accepts
- * numeric timestamps straight through and falls back to 'strtotime()' for
- * human-readable date strings (matching 'TimeHandler' for parity). When the
- * caller supplies both endpoints but no duration, derives it from
- * '(end - start) / 60' clamped at zero.
+ * Field handler for 'smartdate' fields (smart_date contrib module).
  */
 class SmartdateHandler extends AbstractHandler {
 
   /**
    * {@inheritdoc}
-   *
-   * Accepts: a single positional pair '[start, end]', a single keyed
-   * record '['value' => ..., 'end_value' => ..., ...]', or a list of
-   * either form for multi-delta fields. Returns one storage record per
-   * input delta.
    */
-  public function expand($values): array {
+  protected function normalise(mixed $values): array {
     if (!is_array($values) || $values === []) {
       return [];
     }
 
-    $records = (isset($values[0]) && is_array($values[0])) ? $values : [$values];
+    // A list whose first element is an array is treated as a list of
+    // records; anything else is a single delta wrapped in a list.
+    $is_list_of_records = array_is_list($values) && is_array($values[0]);
+
+    if (!$is_list_of_records) {
+      $values = [$values];
+    }
+
+    $records = [];
+
+    foreach ($values as $value) {
+      if (!is_array($value)) {
+        throw new \InvalidArgumentException(sprintf(
+          'Smartdate field delta must be an array (positional [start, end] or keyed value/end_value). Got %s.',
+          get_debug_type($value),
+        ));
+      }
+
+      $records[] = [
+        'value' => $value['value'] ?? $value[0] ?? NULL,
+        'end_value' => $value['end_value'] ?? $value[1] ?? NULL,
+        'duration' => $value['duration'] ?? NULL,
+        'rrule' => $value['rrule'] ?? NULL,
+        'rrule_index' => $value['rrule_index'] ?? NULL,
+        'timezone' => $value['timezone'] ?? NULL,
+      ];
+    }
+
+    return $records;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function doExpand(array $records): array {
     $expanded = [];
 
     foreach ($records as $record) {
-      if (!is_array($record)) {
-        continue;
-      }
+      $start = $this->toTimestamp($record['value']);
+      $end = $this->toTimestamp($record['end_value']);
 
-      $start = $this->toTimestamp($record['value'] ?? $record[0] ?? NULL);
-      $end = $this->toTimestamp($record['end_value'] ?? $record[1] ?? NULL);
+      $duration = $record['duration'];
 
-      $duration = $record['duration'] ?? NULL;
       if ($duration === NULL && $start !== NULL && $end !== NULL) {
         $duration = (int) max(0, ($end - $start) / 60);
       }
@@ -50,8 +68,8 @@ public function expand($values): array {
         'value' => $start,
         'end_value' => $end,
         'duration' => $duration !== NULL ? (int) $duration : 0,
-        'rrule' => $record['rrule'] ?? NULL,
-        'rrule_index' => $record['rrule_index'] ?? NULL,
+        'rrule' => $record['rrule'],
+        'rrule_index' => $record['rrule_index'],
         'timezone' => $record['timezone'] ?? '',
       ];
     }
@@ -60,7 +78,7 @@ public function expand($values): array {
   }
 
   /**
-   * Normalises a start/end input into a Unix timestamp.
+   * Coerces a start/end value into a Unix timestamp.
    *
    * @param mixed $value
    *   A numeric Unix timestamp, a 'strtotime()'-parseable date string,
diff --git a/src/Drupal/Driver/Core/Field/SupportedImageHandler.php b/src/Drupal/Driver/Core/Field/SupportedImageHandler.php
index f6dcd966..856b0fce 100644
--- a/src/Drupal/Driver/Core/Field/SupportedImageHandler.php
+++ b/src/Drupal/Driver/Core/Field/SupportedImageHandler.php
@@ -5,11 +5,8 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Supported Image field handler for Drupal 8+.
+ * Field handler for 'supported_image' fields (supported_image contrib module).
  *
- * Adapted from ImageHandler.
- *
- * @see \Drupal\Driver\Core\Field\ImageHandler
  * @see https://www.drupal.org/project/supported_image
  */
 class SupportedImageHandler extends AbstractHandler {
@@ -17,21 +14,33 @@ class SupportedImageHandler extends AbstractHandler {
   /**
    * {@inheritdoc}
    */
-  public function expand($values): array {
-    // Standardize single/multi-value input.
-    if (is_string($values) || isset($values['target_id'])) {
-      $values = [$values];
+  protected function normalise(mixed $values): array {
+    $records = parent::normalise($values);
+
+    foreach ($records as &$record) {
+      if ($record[$this->mainProperty] === NULL || $record[$this->mainProperty] === '') {
+        throw new \InvalidArgumentException(sprintf('Supported image field "%s" must not be NULL or empty.', $this->mainProperty));
+      }
+
+      $record[$this->mainProperty] = (string) $record[$this->mainProperty];
     }
 
+    return $records;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function doExpand(array $records): array {
     $images = [];
 
-    foreach ($values as $value) {
-      $file_path = (string) ($value['target_id'] ?? $value);
-      $file_extension = pathinfo($file_path, PATHINFO_EXTENSION);
+    foreach ($records as $record) {
+      $file_path = $record[$this->mainProperty];
+      $file_extension = pathinfo((string) $file_path, PATHINFO_EXTENSION);
       $data = file_get_contents($file_path);
 
       if ($data === FALSE) {
-        throw new \Exception("Error reading file");
+        throw new \Exception(sprintf('Error reading file %s.', $file_path));
       }
 
       /** @var \Drupal\file\FileInterface $file */
@@ -40,13 +49,13 @@ public function expand($values): array {
       $file->save();
 
       $images[] = [
-        'target_id' => $file->id(),
-        'alt' => $value['alt'] ?? NULL,
-        'title' => $value['title'] ?? NULL,
-        'caption_value' => $value['caption_value'] ?? NULL,
-        'caption_format' => $value['caption_format'] ?? NULL,
-        'attribution_value' => $value['attribution_value'] ?? NULL,
-        'attribution_format' => $value['attribution_format'] ?? NULL,
+        $this->mainProperty => $file->id(),
+        'alt' => $record['alt'] ?? NULL,
+        'title' => $record['title'] ?? NULL,
+        'caption_value' => $record['caption_value'] ?? NULL,
+        'caption_format' => $record['caption_format'] ?? NULL,
+        'attribution_value' => $record['attribution_value'] ?? NULL,
+        'attribution_format' => $record['attribution_format'] ?? NULL,
       ];
     }
 
diff --git a/src/Drupal/Driver/Core/Field/TextHandler.php b/src/Drupal/Driver/Core/Field/TextHandler.php
index a0002226..54ffad54 100644
--- a/src/Drupal/Driver/Core/Field/TextHandler.php
+++ b/src/Drupal/Driver/Core/Field/TextHandler.php
@@ -5,19 +5,15 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Pass-through handler for 'text' fields.
- *
- * Stores (value, format) per delta; 'text' is the one-line counterpart to
- * 'text_long'. Both share the multi-column shape and therefore need a
- * dedicated pass-through so DefaultHandler does not reject the payload.
+ * Field handler for 'text' fields.
  */
 class TextHandler extends AbstractHandler {
 
   /**
    * {@inheritdoc}
    */
-  public function expand(mixed $values): array {
-    return $this->normalise($values);
+  protected function doExpand(array $records): array {
+    return $records;
   }
 
 }
diff --git a/src/Drupal/Driver/Core/Field/TextLongHandler.php b/src/Drupal/Driver/Core/Field/TextLongHandler.php
index 47ff8650..670b5581 100644
--- a/src/Drupal/Driver/Core/Field/TextLongHandler.php
+++ b/src/Drupal/Driver/Core/Field/TextLongHandler.php
@@ -5,19 +5,15 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Pass-through handler for 'text_long' fields.
- *
- * Stores (value, format) per delta; used for taxonomy term description,
- * paragraph body, custom block body. DefaultHandler cannot marshal it
- * because it is multi-column, so a dedicated pass-through is required.
+ * Field handler for 'text_long' fields.
  */
 class TextLongHandler extends AbstractHandler {
 
   /**
    * {@inheritdoc}
    */
-  public function expand(mixed $values): array {
-    return $this->normalise($values);
+  protected function doExpand(array $records): array {
+    return $records;
   }
 
 }
diff --git a/src/Drupal/Driver/Core/Field/TextWithSummaryHandler.php b/src/Drupal/Driver/Core/Field/TextWithSummaryHandler.php
index 9bb2a755..69bc3f17 100644
--- a/src/Drupal/Driver/Core/Field/TextWithSummaryHandler.php
+++ b/src/Drupal/Driver/Core/Field/TextWithSummaryHandler.php
@@ -5,15 +5,15 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Default field handler for Drupal 8.
+ * Field handler for 'text_with_summary' fields.
  */
 class TextWithSummaryHandler extends AbstractHandler {
 
   /**
    * {@inheritdoc}
    */
-  public function expand(mixed $values): array {
-    return $this->normalise($values);
+  protected function doExpand(array $records): array {
+    return $records;
   }
 
 }
diff --git a/src/Drupal/Driver/Core/Field/TimeHandler.php b/src/Drupal/Driver/Core/Field/TimeHandler.php
index d521daf4..4911eb02 100644
--- a/src/Drupal/Driver/Core/Field/TimeHandler.php
+++ b/src/Drupal/Driver/Core/Field/TimeHandler.php
@@ -5,26 +5,32 @@
 namespace Drupal\Driver\Core\Field;
 
 /**
- * Time field handler for Drupal 8.
+ * Field handler for 'time' fields.
  */
 class TimeHandler extends AbstractHandler {
 
   /**
    * {@inheritdoc}
    */
-  public function expand($values): array {
+  protected function doExpand(array $records): array {
+    $midnight = strtotime('today midnight');
     $seconds = [];
 
-    foreach ($values as $value) {
-      // Numeric values are already in storage format (seconds past midnight).
+    foreach ($records as $record) {
+      $value = $record['value'];
+
       if (is_numeric($value)) {
         $seconds[] = $value;
         continue;
       }
 
-      // Support anything that can be passed to strtotime.
-      $midnight = strtotime('today midnight');
-      $seconds[] = strtotime((string) $value) - $midnight;
+      $timestamp = strtotime((string) $value);
+
+      if ($timestamp === FALSE) {
+        throw new \InvalidArgumentException(sprintf('Time field value "%s" is not parseable.', (string) $value));
+      }
+
+      $seconds[] = $timestamp - $midnight;
     }
 
     return $seconds;
diff --git a/tests/Drupal/Tests/Driver/Kernel/Core/CoreEntityMethodsKernelTest.php b/tests/Drupal/Tests/Driver/Kernel/Core/CoreEntityMethodsKernelTest.php
index 97715881..7b0c77c8 100644
--- a/tests/Drupal/Tests/Driver/Kernel/Core/CoreEntityMethodsKernelTest.php
+++ b/tests/Drupal/Tests/Driver/Kernel/Core/CoreEntityMethodsKernelTest.php
@@ -101,7 +101,7 @@ public function testEntityCreateAutoExpandsBaseFieldsSetOnStub(): void {
 
     $this->core->entityCreate($stub);
 
-    $this->assertSame(['uma'], $stub->getValue('name'), 'base field "name" was routed through the handler pipeline.');
+    $this->assertSame([['value' => 'uma']], $stub->getValue('name'), 'base field "name" was routed through the handler pipeline.');
   }
 
   /**
diff --git a/tests/Drupal/Tests/Driver/Kernel/Core/Field/FieldHandlerRegistryKernelTest.php b/tests/Drupal/Tests/Driver/Kernel/Core/Field/FieldHandlerRegistryKernelTest.php
index ee31f746..4098d5ea 100644
--- a/tests/Drupal/Tests/Driver/Kernel/Core/Field/FieldHandlerRegistryKernelTest.php
+++ b/tests/Drupal/Tests/Driver/Kernel/Core/Field/FieldHandlerRegistryKernelTest.php
@@ -88,17 +88,16 @@ class MarkerTextWithSummaryHandler extends AbstractHandler {
   /**
    * {@inheritdoc}
    */
-  public function expand($values): array {
+  protected function doExpand(array $records): array {
     // Replace each delta's 'value' with the marker while preserving other
     // columns. The kernel-test helper asserts the stored value equals what
     // the handler emitted, so the round-trip only passes if this handler
     // ran.
     $emitted = [];
 
-    foreach ((array) $values as $delta) {
-      $delta = is_array($delta) ? $delta : ['value' => $delta];
-      $delta['value'] = self::MARKER;
-      $emitted[] = $delta;
+    foreach ($records as $record) {
+      $record['value'] = self::MARKER;
+      $emitted[] = $record;
     }
 
     return $emitted;
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/CoreFieldHandlerLookupTest.php b/tests/Drupal/Tests/Driver/Unit/Core/CoreFieldHandlerLookupTest.php
index 65a18d7b..37ac01d3 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/CoreFieldHandlerLookupTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/CoreFieldHandlerLookupTest.php
@@ -212,8 +212,8 @@ class CustomFieldHandler extends AbstractHandler {
   /**
    * {@inheritdoc}
    */
-  public function expand($values): array {
-    return (array) $values;
+  protected function doExpand(array $records): array {
+    return $records;
   }
 
 }
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/AbstractHandlerNormaliseTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/AbstractHandlerNormaliseTest.php
index 29b96dbc..4d0c6fc3 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/AbstractHandlerNormaliseTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/AbstractHandlerNormaliseTest.php
@@ -20,17 +20,13 @@ class AbstractHandlerNormaliseTest extends TestCase {
   /**
    * Tests every accepted and rejected input shape for normalise().
    *
-   * Each data row carries the input, the field's main property name, the
-   * expected output (or NULL when an exception is expected), the expected
-   * exception class (or NULL for the happy path), and the expected
-   * substring of the exception message (or NULL).
-   *
    * @param mixed $input
    *   The loose input to feed to normalise().
    * @param string $main_property
    *   The field's main property name (returned by the mocked fieldInfo).
    * @param array<int, array<string, mixed>>|null $expected
-   *   The expected canonical list of records, or NULL when expecting a throw.
+   *   The expected canonical list of records, or NULL when an exception is
+   *   expected.
    * @param string|null $exception
    *   The expected exception class, or NULL for the happy path.
    * @param string|null $exception_message
@@ -236,18 +232,14 @@ protected function createHandler(string $main_property): AbstractHandler {
 
 /**
  * Concrete AbstractHandler subclass used only by the normalise() tests.
- *
- * Provides the abstract surface (expand()) without doing any real work,
- * so reflection-based tests can exercise the inherited normalise() helper
- * in isolation from any specific field handler's resolution behaviour.
  */
 final class NormaliseTestHandler extends AbstractHandler {
 
   /**
    * {@inheritdoc}
    */
-  public function expand(mixed $values): array {
-    return $this->normalise($values);
+  protected function doExpand(array $records): array {
+    return $records;
   }
 
 }
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/AddressHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/AddressHandlerTest.php
index 446826c7..f8c97b08 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/AddressHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/AddressHandlerTest.php
@@ -6,7 +6,7 @@
 
 use Drupal\Core\Field\FieldDefinitionInterface;
 use Drupal\Driver\Core\Field\AddressHandler;
-use PHPUnit\Framework\TestCase;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use PHPUnit\Framework\Attributes\Group;
 
 /**
@@ -15,106 +15,104 @@
  * @group fields
  */
 #[Group('fields')]
-class AddressHandlerTest extends TestCase {
+class AddressHandlerTest extends FieldHandlerUnitTestBase {
 
   /**
-   * Tests that a string value uses the first visible field.
+   * {@inheritdoc}
    */
-  public function testStringValueUsesFirstVisibleField(): void {
-    $handler = $this->createHandler();
-
-    $result = $handler->expand(['Just a name']);
-
-    $this->assertSame([['given_name' => 'Just a name']], $result);
+  protected function createHandler(): FieldHandlerInterface {
+    return $this->createHandlerWithSettings();
   }
 
   /**
-   * Tests that keyed values are preserved and defaults filled in.
+   * {@inheritdoc}
    */
-  public function testKeyedValuesAreKeptAndDefaultCountryApplied(): void {
-    $handler = $this->createHandler();
-
-    $result = $handler->expand([
-      [
-        'given_name' => 'John',
-        'family_name' => 'Doe',
-      ],
-    ]);
-
-    $this->assertSame([
+  public static function dataProviderExpand(): \Iterator {
+    yield 'bare string maps to first visible field plus country fallback' => [
+      'Just a name',
+      [['given_name' => 'Just a name', 'country_code' => 'AU']],
+      NULL,
+      NULL,
+    ];
+    yield 'keyed record auto-wrapped with country backfill' => [
+      ['given_name' => 'John', 'family_name' => 'Doe'],
+      [['given_name' => 'John', 'family_name' => 'Doe', 'country_code' => 'AU']],
+      NULL,
+      NULL,
+    ];
+    yield 'list with keyed record' => [
+      [['given_name' => 'John', 'family_name' => 'Doe']],
+      [['given_name' => 'John', 'family_name' => 'Doe', 'country_code' => 'AU']],
+      NULL,
+      NULL,
+    ];
+    yield 'positional indices fill visible fields in order' => [
+      [['John', 'Doe']],
+      [['given_name' => 'John', 'additional_name' => 'Doe', 'country_code' => 'AU']],
+      NULL,
+      NULL,
+    ];
+    yield 'explicit country_code preserved' => [
+      [['country_code' => 'US']],
+      [['country_code' => 'US']],
+      NULL,
+      NULL,
+    ];
+    yield 'multi-delta backfills each record' => [
       [
-        'given_name' => 'John',
-        'family_name' => 'Doe',
-        'country_code' => 'AU',
+        ['given_name' => 'John'],
+        ['given_name' => 'Jane', 'country_code' => 'US'],
       ],
-    ], $result);
-  }
-
-  /**
-   * Tests that numeric indices are assigned in the order of visible fields.
-   */
-  public function testNumericIndicesMapToVisibleFieldOrder(): void {
-    $handler = $this->createHandler();
-
-    $result = $handler->expand([
-      ['John', 'Doe'],
-    ]);
-
-    $this->assertSame([
       [
-        'given_name' => 'John',
-        'additional_name' => 'Doe',
-        'country_code' => 'AU',
+        ['given_name' => 'John', 'country_code' => 'AU'],
+        ['given_name' => 'Jane', 'country_code' => 'US'],
       ],
-    ], $result);
+      NULL,
+      NULL,
+    ];
+
+    yield 'unknown sub-field key rejected' => [
+      [['unknown_key' => 'value']],
+      NULL,
+      \RuntimeException::class,
+      'Invalid address sub-field key: unknown_key.',
+    ];
   }
 
   /**
    * Tests that hidden fields are removed from the visible field list.
    */
   public function testHiddenFieldsAreSkippedForNumericIndices(): void {
-    $handler = $this->createHandler([
+    $handler = $this->createHandlerWithSettings([
       'givenName' => ['override' => 'hidden'],
       'additionalName' => ['override' => 'hidden'],
     ]);
 
-    $result = $handler->expand([
-      ['Doe'],
-    ]);
-
-    $this->assertSame([
-      [
-        'family_name' => 'Doe',
-        'country_code' => 'AU',
-      ],
-    ], $result);
+    $this->assertSame(
+      [['family_name' => 'Doe', 'country_code' => 'AU']],
+      $handler->expand([['Doe']]),
+    );
   }
 
   /**
    * Tests that non-hidden overrides do not alter the visible field list.
    */
   public function testNonHiddenOverridesAreIgnored(): void {
-    $handler = $this->createHandler([
+    $handler = $this->createHandlerWithSettings([
       'givenName' => ['override' => 'optional'],
     ]);
 
-    $result = $handler->expand([
-      ['John'],
-    ]);
-
-    $this->assertSame([
-      [
-        'given_name' => 'John',
-        'country_code' => 'AU',
-      ],
-    ], $result);
+    $this->assertSame(
+      [['given_name' => 'John', 'country_code' => 'AU']],
+      $handler->expand([['John']]),
+    );
   }
 
   /**
    * Tests that excess numeric indices trigger an exception.
    */
   public function testTooManyNumericIndicesThrows(): void {
-    $handler = $this->createHandler([
+    $handler = $this->createHandlerWithSettings([
       'additionalName' => ['override' => 'hidden'],
       'familyName' => ['override' => 'hidden'],
       'organization' => ['override' => 'hidden'],
@@ -130,36 +128,7 @@ public function testTooManyNumericIndicesThrows(): void {
     $this->expectException(\RuntimeException::class);
     $this->expectExceptionMessage('Too many address sub-field values supplied; only 1 visible fields available.');
 
-    $handler->expand([
-      ['John', 'Extra'],
-    ]);
-  }
-
-  /**
-   * Tests that a non-numeric, unknown sub-field key throws an exception.
-   */
-  public function testUnknownKeyThrows(): void {
-    $handler = $this->createHandler();
-
-    $this->expectException(\RuntimeException::class);
-    $this->expectExceptionMessage('Invalid address sub-field key: unknown_key.');
-
-    $handler->expand([
-      ['unknown_key' => 'value'],
-    ]);
-  }
-
-  /**
-   * Tests that an explicit country_code is not overridden by the default.
-   */
-  public function testExplicitCountryCodeIsPreserved(): void {
-    $handler = $this->createHandler();
-
-    $result = $handler->expand([
-      ['country_code' => 'US'],
-    ]);
-
-    $this->assertSame([['country_code' => 'US']], $result);
+    $handler->expand([['John', 'Extra']]);
   }
 
   /**
@@ -169,11 +138,8 @@ public function testExplicitCountryCodeIsPreserved(): void {
    *   Address field override settings.
    * @param array<string, string> $available_countries
    *   Available countries keyed by code.
-   *
-   * @return \Drupal\Driver\Core\Field\AddressHandler
-   *   Handler instance with fieldConfig populated.
    */
-  protected function createHandler(array $field_overrides = [], array $available_countries = ['AU' => 'AU']): AddressHandler {
+  protected function createHandlerWithSettings(array $field_overrides = [], array $available_countries = ['AU' => 'AU']): AddressHandler {
     $field_config = $this->createMock(FieldDefinitionInterface::class);
     $field_config->method('getSettings')->willReturn([
       'field_overrides' => $field_overrides,
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/BooleanHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/BooleanHandlerTest.php
new file mode 100644
index 00000000..013c27d9
--- /dev/null
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/BooleanHandlerTest.php
@@ -0,0 +1,84 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\Driver\Unit\Core\Field;
+
+use Drupal\Core\Field\FieldDefinitionInterface;
+use Drupal\Driver\Core\Field\AbstractHandler;
+use Drupal\Driver\Core\Field\BooleanHandler;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
+use PHPUnit\Framework\Attributes\Group;
+
+/**
+ * Tests the BooleanHandler field handler.
+ *
+ * @group fields
+ */
+#[Group('fields')]
+class BooleanHandlerTest extends FieldHandlerUnitTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function createHandler(): FieldHandlerInterface {
+    $field_config = $this->createMock(FieldDefinitionInterface::class);
+    $field_config->method('getSettings')->willReturn([
+      'on_label' => 'Published',
+      'off_label' => 'Draft',
+    ]);
+
+    $reflection = new \ReflectionClass(BooleanHandler::class);
+    $handler = $reflection->newInstanceWithoutConstructor();
+
+    $config_property = new \ReflectionProperty(BooleanHandler::class, 'fieldConfig');
+    $config_property->setValue($handler, $field_config);
+
+    $main_property = new \ReflectionProperty(AbstractHandler::class, 'mainProperty');
+    $main_property->setValue($handler, 'value');
+
+    return $handler;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function dataProviderExpand(): \Iterator {
+    yield 'canonical yes resolves to 1' => ['Yes', [1], NULL, NULL];
+    yield 'canonical no resolves to 0' => ['no', [0], NULL, NULL];
+    yield 'field on_label resolves to 1' => ['Published', [1], NULL, NULL];
+    yield 'field off_label resolves to 0' => ['Draft', [0], NULL, NULL];
+    yield 'mixed list of labels and canonical' => [
+      ['Published', 'no', 'true'],
+      [1, 0, 1],
+      NULL,
+      NULL,
+    ];
+    yield 'list of canonical forms' => [
+      ['1', '0', 'true', 'false', 'yes', 'no', 'on', 'off'],
+      [1, 0, 1, 0, 1, 0, 1, 0],
+      NULL,
+      NULL,
+    ];
+
+    yield 'unrecognised value rejected' => [
+      ['maybe'],
+      NULL,
+      \RuntimeException::class,
+      'Cannot convert "maybe" to a boolean',
+    ];
+    yield 'mixed positional and named keys rejected' => [
+      ['Yes', 'extra' => 'unexpected'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field value cannot mix positional and named keys',
+    ];
+    yield 'record missing main property rejected' => [
+      ['unexpected' => 'oops'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field record must include the main property "value"',
+    ];
+  }
+
+}
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/DaterangeHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/DaterangeHandlerTest.php
index 94336d60..f3a26bd9 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/DaterangeHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/DaterangeHandlerTest.php
@@ -8,21 +8,19 @@
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Config\ImmutableConfig;
 use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\Core\Field\FieldStorageDefinitionInterface;
 use Drupal\datetime\Plugin\Field\FieldType\DateTimeItemInterface;
 use Drupal\Driver\Core\Field\DaterangeHandler;
-use PHPUnit\Framework\TestCase;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use PHPUnit\Framework\Attributes\Group;
 
 /**
  * Tests the DaterangeHandler field handler.
  *
- * Only empty/null ranges are exercised - full date parsing exercises
- * DrupalDateTime and requires the full Drupal container.
- *
  * @group fields
  */
 #[Group('fields')]
-class DaterangeHandlerTest extends TestCase {
+class DaterangeHandlerTest extends FieldHandlerUnitTestBase {
 
   /**
    * {@inheritdoc}
@@ -54,21 +52,73 @@ protected function tearDown(): void {
   }
 
   /**
-   * Tests that empty start/end values produce NULL entries.
+   * {@inheritdoc}
    */
-  public function testExpandHandlesEmptyValuesAsNull(): void {
+  protected function createHandler(): FieldHandlerInterface {
+    $field_info = $this->createMock(FieldStorageDefinitionInterface::class);
+    $field_info->method('getSetting')
+      ->with('datetime_type')
+      ->willReturn('datetime');
+
     $reflection = new \ReflectionClass(DaterangeHandler::class);
     $handler = $reflection->newInstanceWithoutConstructor();
 
-    $result = $handler->expand([
-      ['value' => NULL, 'end_value' => NULL],
-      [NULL, NULL],
-    ]);
+    $info_property = new \ReflectionProperty(DaterangeHandler::class, 'fieldInfo');
+    $info_property->setValue($handler, $field_info);
 
-    $this->assertSame([
-      ['value' => NULL, 'end_value' => NULL],
+    return $handler;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function dataProviderExpand(): \Iterator {
+    yield 'empty array returns empty list' => [
+      [],
+      [],
+      NULL,
+      NULL,
+    ];
+    yield 'NULL endpoints stay NULL' => [
+      [['value' => NULL, 'end_value' => NULL]],
+      [['value' => NULL, 'end_value' => NULL]],
+      NULL,
+      NULL,
+    ];
+    yield 'positional NULL pair stays NULL' => [
+      [[NULL, NULL]],
+      [['value' => NULL, 'end_value' => NULL]],
+      NULL,
+      NULL,
+    ];
+    yield 'single keyed record auto-wrapped' => [
       ['value' => NULL, 'end_value' => NULL],
-    ], $result);
+      [['value' => NULL, 'end_value' => NULL]],
+      NULL,
+      NULL,
+    ];
+    yield 'multi-delta NULL endpoints' => [
+      [
+        ['value' => NULL, 'end_value' => NULL],
+        ['value' => NULL, 'end_value' => NULL],
+      ],
+      [
+        ['value' => NULL, 'end_value' => NULL],
+        ['value' => NULL, 'end_value' => NULL],
+      ],
+      NULL,
+      NULL,
+    ];
+
+    yield 'non-array element in list rejected' => [
+      [
+        ['value' => '2026-07-15T09:00:00', 'end_value' => '2026-07-15T17:00:00'],
+        'not-a-record',
+      ],
+      NULL,
+      \InvalidArgumentException::class,
+      'Daterange field record must be an array',
+    ];
   }
 
   /**
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/DatetimeHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/DatetimeHandlerTest.php
index d2c6b284..07d8a992 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/DatetimeHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/DatetimeHandlerTest.php
@@ -4,7 +4,6 @@
 
 namespace Drupal\Tests\Driver\Unit\Core\Field;
 
-use PHPUnit\Framework\Attributes\DataProvider;
 use Composer\InstalledVersions;
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Config\ImmutableConfig;
@@ -13,20 +12,20 @@
 use Drupal\datetime\Plugin\Field\FieldType\DateTimeItemInterface;
 use Drupal\Driver\Core\Field\AbstractHandler;
 use Drupal\Driver\Core\Field\DatetimeHandler;
-use PHPUnit\Framework\TestCase;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use PHPUnit\Framework\Attributes\Group;
 
 /**
  * Tests the DatetimeHandler field handler.
  *
- * Full date-parsing behaviour exercises DrupalDateTime, which in turn requires
- * the language_manager service and a full Drupal container, so only the
- * early-return paths (empty values) are asserted here.
+ * Full date parsing exercises 'DrupalDateTime' which needs the
+ * 'language_manager' service and a real Drupal container, so only the
+ * empty/NULL early-return cases are asserted here.
  *
  * @group fields
  */
 #[Group('fields')]
-class DatetimeHandlerTest extends TestCase {
+class DatetimeHandlerTest extends FieldHandlerUnitTestBase {
 
   /**
    * {@inheritdoc}
@@ -58,78 +57,73 @@ protected function tearDown(): void {
   }
 
   /**
-   * Tests that empty values are accepted in every input shape.
-   *
-   * @param mixed $input
-   *   Any of the loose shapes 'normalise()' accepts.
-   * @param array<int, array<string, mixed>> $expected
-   *   The expected expand() output: a list of records keyed by 'value'.
-   *
-   * @dataProvider dataProviderExpandPreservesEmptyValuesAsNull
+   * {@inheritdoc}
    */
-  #[DataProvider('dataProviderExpandPreservesEmptyValuesAsNull')]
-  public function testExpandPreservesEmptyValuesAsNull(mixed $input, array $expected): void {
-    $handler = $this->createHandler('datetime');
+  protected function createHandler(): FieldHandlerInterface {
+    $field_info = $this->createMock(FieldStorageDefinitionInterface::class);
+    $field_info->method('getSetting')
+      ->with('datetime_type')
+      ->willReturn('datetime');
 
-    $result = $handler->expand($input);
+    $reflection = new \ReflectionClass(DatetimeHandler::class);
+    $handler = $reflection->newInstanceWithoutConstructor();
+
+    $info_property = new \ReflectionProperty(DatetimeHandler::class, 'fieldInfo');
+    $info_property->setValue($handler, $field_info);
 
-    $this->assertSame($expected, $result);
+    $main_property = new \ReflectionProperty(AbstractHandler::class, 'mainProperty');
+    $main_property->setValue($handler, 'value');
+
+    return $handler;
   }
 
   /**
-   * Data provider for testExpandPreservesEmptyValuesAsNull().
-   *
-   * Non-empty dates exercise DrupalDateTime, which needs the language_manager
-   * service and a full container; those cases live in the kernel test. The
-   * shape coverage here uses empty values so that 'formatDateValue()' early
-   * returns and the only assertion is on the normalised record shape.
+   * {@inheritdoc}
    */
-  public static function dataProviderExpandPreservesEmptyValuesAsNull(): \Iterator {
-    yield 'bare empty string scalar' => [
+  public static function dataProviderExpand(): \Iterator {
+    yield 'bare empty string becomes NULL' => [
       '',
       [['value' => NULL]],
+      NULL,
+      NULL,
     ];
-    yield 'bare NULL scalar' => [
+    yield 'bare NULL becomes NULL' => [
       NULL,
       [['value' => NULL]],
+      NULL,
+      NULL,
     ];
     yield 'list of empty scalars' => [
       ['', NULL],
       [['value' => NULL], ['value' => NULL]],
+      NULL,
+      NULL,
     ];
     yield 'single record with empty value' => [
       ['value' => ''],
       [['value' => NULL]],
+      NULL,
+      NULL,
     ];
     yield 'list of records with empty values' => [
       [['value' => ''], ['value' => NULL]],
       [['value' => NULL], ['value' => NULL]],
+      NULL,
+      NULL,
     ];
-  }
-
-  /**
-   * Creates a DatetimeHandler with fieldInfo and main property injected.
-   *
-   * The fieldInfo mock is still needed for getSetting('datetime_type')
-   * (used by formatDateValue); mainProperty is injected separately because
-   * normalise() reads it as a property, not via fieldInfo.
-   */
-  protected function createHandler(string $datetime_type): DatetimeHandler {
-    $field_info = $this->createMock(FieldStorageDefinitionInterface::class);
-    $field_info->method('getSetting')
-      ->with('datetime_type')
-      ->willReturn($datetime_type);
-
-    $reflection = new \ReflectionClass(DatetimeHandler::class);
-    $handler = $reflection->newInstanceWithoutConstructor();
-
-    $info_property = new \ReflectionProperty(DatetimeHandler::class, 'fieldInfo');
-    $info_property->setValue($handler, $field_info);
-
-    $main_property = new \ReflectionProperty(AbstractHandler::class, 'mainProperty');
-    $main_property->setValue($handler, 'value');
 
-    return $handler;
+    yield 'mixed positional and named keys rejected' => [
+      ['2026-07-15T09:00:00', 'extra' => 'oops'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field value cannot mix positional and named keys',
+    ];
+    yield 'record missing main property rejected' => [
+      ['format' => 'datetime'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field record must include the main property "value"',
+    ];
   }
 
   /**
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/DefaultHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/DefaultHandlerTest.php
index ce12e200..5e34ffad 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/DefaultHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/DefaultHandlerTest.php
@@ -6,9 +6,10 @@
 
 use Drupal\Core\Field\FieldDefinitionInterface;
 use Drupal\Core\Field\FieldStorageDefinitionInterface;
+use Drupal\Driver\Core\Field\AbstractHandler;
 use Drupal\Driver\Core\Field\DefaultHandler;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use PHPUnit\Framework\Attributes\Group;
-use PHPUnit\Framework\TestCase;
 
 /**
  * Tests the DefaultHandler field handler.
@@ -16,15 +17,56 @@
  * @group fields
  */
 #[Group('fields')]
-class DefaultHandlerTest extends TestCase {
+class DefaultHandlerTest extends FieldHandlerUnitTestBase {
 
   /**
-   * Tests that a single 'value' column passes through unchanged.
+   * {@inheritdoc}
    */
-  public function testExpandReturnsValuesForSingleValueColumn(): void {
-    $handler = $this->handlerWithColumns(['value' => []]);
+  protected function createHandler(): FieldHandlerInterface {
+    return $this->handlerWithColumns(['value' => []]);
+  }
 
-    $this->assertSame(['one', 'two'], $handler->expand(['one', 'two']));
+  /**
+   * {@inheritdoc}
+   */
+  public static function dataProviderExpand(): \Iterator {
+    yield 'bare scalar' => [
+      'hello',
+      [['value' => 'hello']],
+      NULL,
+      NULL,
+    ];
+    yield 'list of scalars' => [
+      ['one', 'two'],
+      [['value' => 'one'], ['value' => 'two']],
+      NULL,
+      NULL,
+    ];
+    yield 'records pass through unchanged' => [
+      [['value' => 'one'], ['value' => 'two']],
+      [['value' => 'one'], ['value' => 'two']],
+      NULL,
+      NULL,
+    ];
+    yield 'integer scalar' => [
+      42,
+      [['value' => 42]],
+      NULL,
+      NULL,
+    ];
+
+    yield 'mixed positional and named keys rejected' => [
+      ['hello', 'extra' => 'unexpected'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field value cannot mix positional and named keys',
+    ];
+    yield 'record missing main property rejected' => [
+      ['unexpected' => 'oops'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field record must include the main property "value"',
+    ];
   }
 
   /**
@@ -37,7 +79,7 @@ public function testExpandThrowsForMultipleColumns(): void {
     $this->expectExceptionMessage('No dedicated handler is registered');
     $this->expectExceptionMessage('2 column(s) (value, format)');
 
-    $handler->expand('hello');
+    $handler->expand([['value' => 'hello']]);
   }
 
   /**
@@ -49,15 +91,14 @@ public function testExpandThrowsForSingleColumnNotNamedValue(): void {
     $this->expectException(\RuntimeException::class);
     $this->expectExceptionMessage('target_id');
 
-    $handler->expand(42);
+    $handler->expand([['value' => 42]]);
   }
 
   /**
    * Builds a DefaultHandler wired to a mocked field storage/config pair.
    *
    * @param array<string, array<string, mixed>> $columns
-   *   Column descriptors keyed by column name (the content is irrelevant;
-   *   only the array keys are inspected by DefaultHandler).
+   *   Column descriptors keyed by column name.
    */
   protected function handlerWithColumns(array $columns): DefaultHandler {
     $storage = $this->createMock(FieldStorageDefinitionInterface::class);
@@ -71,11 +112,16 @@ protected function handlerWithColumns(array $columns): DefaultHandler {
 
     $reflection = new \ReflectionClass(DefaultHandler::class);
     $handler = $reflection->newInstanceWithoutConstructor();
+
     $info_prop = $reflection->getParentClass()->getProperty('fieldInfo');
     $info_prop->setValue($handler, $storage);
+
     $config_prop = $reflection->getParentClass()->getProperty('fieldConfig');
     $config_prop->setValue($handler, $config);
 
+    $main_property = new \ReflectionProperty(AbstractHandler::class, 'mainProperty');
+    $main_property->setValue($handler, 'value');
+
     return $handler;
   }
 
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/EntityReferenceHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/EntityReferenceHandlerTest.php
index 99d177dd..c5ebf1db 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/EntityReferenceHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/EntityReferenceHandlerTest.php
@@ -4,91 +4,66 @@
 
 namespace Drupal\Tests\Driver\Unit\Core\Field;
 
+use PHPUnit\Framework\MockObject\MockObject;
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Core\Entity\EntityTypeInterface;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Entity\Query\QueryInterface;
 use Drupal\Core\Field\FieldDefinitionInterface;
 use Drupal\Core\Field\FieldStorageDefinitionInterface;
+use Drupal\Driver\Core\Field\AbstractHandler;
 use Drupal\Driver\Core\Field\EntityReferenceHandler;
-use PHPUnit\Framework\TestCase;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use PHPUnit\Framework\Attributes\Group;
 
 /**
  * Tests the EntityReferenceHandler field handler.
  *
- * Full happy-path coverage requires a live Drupal kernel; these tests focus
- * on the helper logic and error paths that can be verified in isolation.
- *
  * @group fields
  */
 #[Group('fields')]
-class EntityReferenceHandlerTest extends TestCase {
+class EntityReferenceHandlerTest extends FieldHandlerUnitTestBase {
 
   /**
-   * {@inheritdoc}
-   */
-  protected function tearDown(): void {
-    \Drupal::unsetContainer();
-    parent::tearDown();
-  }
-
-  /**
-   * Tests that unknown values raise an exception.
+   * Label -> id lookup the entity query stub returns matches against.
+   *
+   * @var array<string, int>
    */
-  public function testExpandThrowsWhenNoEntityMatches(): void {
-    $handler = $this->createHandler('node', []);
-    $this->setUpEmptyQueryContainer('node');
-
-    $this->expectException(\Exception::class);
-    $this->expectExceptionMessage("No entity 'Missing' of type 'node' exists.");
-
-    $handler->expand(['Missing']);
-  }
+  protected const KNOWN_LABELS = [
+    'alice' => 7,
+    'bob' => 8,
+  ];
 
   /**
-   * Tests getTargetBundles() returns configured bundles.
+   * {@inheritdoc}
    */
-  public function testGetTargetBundlesReturnsConfiguredBundles(): void {
-    $handler = $this->createHandler('node', ['article', 'page']);
-
-    $reflection = new \ReflectionMethod(EntityReferenceHandler::class, 'getTargetBundles');
+  protected function setUp(): void {
+    parent::setUp();
 
-    $this->assertSame(['article', 'page'], $reflection->invoke($handler));
+    $container = new ContainerBuilder();
+    $container->set('entity_type.manager', $this->createEntityTypeManager(self::KNOWN_LABELS));
+    \Drupal::setContainer($container);
   }
 
   /**
-   * Tests getTargetBundles() returns NULL when none configured.
+   * {@inheritdoc}
    */
-  public function testGetTargetBundlesReturnsNullWhenEmpty(): void {
-    $handler = $this->createHandler('node', []);
-
-    $reflection = new \ReflectionMethod(EntityReferenceHandler::class, 'getTargetBundles');
-
-    $this->assertNull($reflection->invoke($handler));
+  protected function tearDown(): void {
+    \Drupal::unsetContainer();
+    parent::tearDown();
   }
 
   /**
-   * Creates an EntityReferenceHandler with mocked fieldInfo and fieldConfig.
-   *
-   * @param string $target_type
-   *   The target entity type ID.
-   * @param array<string, string> $target_bundles
-   *   Target bundle restrictions.
-   *
-   * @return \Drupal\Driver\Core\Field\EntityReferenceHandler
-   *   A handler instance with fieldInfo and fieldConfig populated.
+   * {@inheritdoc}
    */
-  protected function createHandler(string $target_type, array $target_bundles = []): EntityReferenceHandler {
+  protected function createHandler(): FieldHandlerInterface {
     $field_info = $this->createMock(FieldStorageDefinitionInterface::class);
     $field_info->method('getSetting')
       ->with('target_type')
-      ->willReturn($target_type);
+      ->willReturn('user');
 
-    $handler_settings = $target_bundles !== [] ? ['target_bundles' => $target_bundles] : [];
     $field_config = $this->createMock(FieldDefinitionInterface::class);
-    $field_config->method('getSettings')
-      ->willReturn(['handler_settings' => $handler_settings]);
+    $field_config->method('getSettings')->willReturn(['handler_settings' => []]);
 
     $reflection = new \ReflectionClass(EntityReferenceHandler::class);
     $handler = $reflection->newInstanceWithoutConstructor();
@@ -99,29 +74,135 @@ protected function createHandler(string $target_type, array $target_bundles = []
     $config_property = new \ReflectionProperty(EntityReferenceHandler::class, 'fieldConfig');
     $config_property->setValue($handler, $field_config);
 
+    $main_property = new \ReflectionProperty(AbstractHandler::class, 'mainProperty');
+    $main_property->setValue($handler, 'target_id');
+
     return $handler;
   }
 
   /**
-   * Sets up a Drupal container whose queries always return no results.
+   * {@inheritdoc}
+   */
+  public static function dataProviderExpand(): \Iterator {
+    yield 'bare label resolves to id' => [
+      'alice',
+      [['target_id' => 7]],
+      NULL,
+      NULL,
+    ];
+    yield 'list of one label' => [
+      ['alice'],
+      [['target_id' => 7]],
+      NULL,
+      NULL,
+    ];
+    yield 'list of multiple labels' => [
+      ['alice', 'bob'],
+      [['target_id' => 7], ['target_id' => 8]],
+      NULL,
+      NULL,
+    ];
+    yield 'record with target_id label' => [
+      [['target_id' => 'alice']],
+      [['target_id' => 7]],
+      NULL,
+      NULL,
+    ];
+    yield 'record preserves extras' => [
+      [['target_id' => 'alice', 'display' => 1]],
+      [['target_id' => 7, 'display' => 1]],
+      NULL,
+      NULL,
+    ];
+    yield 'integer id bypasses validation query' => [
+      [42],
+      [['target_id' => 42]],
+      NULL,
+      NULL,
+    ];
+
+    yield 'unknown label throws' => [
+      ['nobody'],
+      NULL,
+      \Exception::class,
+      "No entity 'nobody' of type 'user' exists.",
+    ];
+    yield 'mixed positional and named keys rejected' => [
+      ['alice', 'extra' => 'oops'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field value cannot mix positional and named keys',
+    ];
+    yield 'record missing main property rejected' => [
+      ['display' => 1],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field record must include the main property "target_id"',
+    ];
+  }
+
+  /**
+   * Builds an entity_type.manager + entity-query stub keyed by label.
+   *
+   * @param array<string, int> $known_labels
+   *   Label-to-id index the entity query returns matches from.
    */
-  protected function setUpEmptyQueryContainer(string $entity_type_id): void {
-    $definition = $this->createMock(EntityTypeInterface::class);
-    $definition->method('getKey')->willReturnMap([
-      ['id', 'nid'],
-      ['label', 'title'],
-      ['bundle', 'type'],
+  protected function createEntityTypeManager(array $known_labels): object {
+    $entity_type = $this->createMock(EntityTypeInterface::class);
+    $entity_type->method('getKey')->willReturnMap([
+      ['id', 'uid'],
+      ['label', 'name'],
+      ['bundle', FALSE],
     ]);
 
+    $query = $this->createQueryStub($known_labels);
+    $storage = $this->createStorageWithQuery($query);
+
+    $entity_type_manager = $this->createMock(EntityTypeManagerInterface::class);
+    $entity_type_manager->method('getDefinition')->willReturn($entity_type);
+    $entity_type_manager->method('getStorage')->willReturn($storage);
+
+    return $entity_type_manager;
+  }
+
+  /**
+   * Builds an entity query mock backed by the label-to-id index.
+   *
+   * @param array<string, int> $known_labels
+   *   Label-to-id index.
+   */
+  protected function createQueryStub(array $known_labels): QueryInterface {
     $query = $this->createMock(QueryInterface::class);
-    $query->method('orConditionGroup')->willReturn($query);
-    $query->method('condition')->willReturnSelf();
     $query->method('accessCheck')->willReturnSelf();
-    $query->method('execute')->willReturn([]);
+    $query->method('orConditionGroup')->willReturnSelf();
+
+    $captured_label = NULL;
+    $query->method('condition')
+      ->willReturnCallback(function (mixed $field, mixed $value = NULL) use ($query, &$captured_label): MockObject {
+        if (is_string($field) && in_array($field, ['name', 'title', 'label'], TRUE) && $value !== NULL) {
+          $captured_label = (string) $value;
+        }
+
+        return $query;
+      });
+
+    $query->method('execute')
+      ->willReturnCallback(function () use (&$captured_label, $known_labels): array {
+        return $captured_label !== NULL && isset($known_labels[$captured_label])
+          ? [$known_labels[$captured_label]]
+          : [];
+      });
+
+    return $query;
+  }
 
-    $storage = new class($query) {
+  /**
+   * Builds an entity storage stub whose 'getQuery()' returns the given query.
+   */
+  protected function createStorageWithQuery(QueryInterface $query): object {
+    return new class($query) {
 
-      public function __construct(private readonly QueryInterface $query) {}
+      public function __construct(protected readonly QueryInterface $query) {}
 
       /**
        * Returns the injected entity query.
@@ -131,14 +212,6 @@ public function getQuery(): QueryInterface {
       }
 
     };
-
-    $entity_type_manager = $this->createMock(EntityTypeManagerInterface::class);
-    $entity_type_manager->method('getDefinition')->willReturn($definition);
-    $entity_type_manager->method('getStorage')->willReturn($storage);
-
-    $container = new ContainerBuilder();
-    $container->set('entity_type.manager', $entity_type_manager);
-    \Drupal::setContainer($container);
   }
 
 }
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/EntityReferenceRevisionsHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/EntityReferenceRevisionsHandlerTest.php
index d6511e88..77718ff0 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/EntityReferenceRevisionsHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/EntityReferenceRevisionsHandlerTest.php
@@ -4,146 +4,128 @@
 
 namespace Drupal\Tests\Driver\Unit\Core\Field;
 
+use PHPUnit\Framework\MockObject\MockObject;
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Core\Entity\EntityStorageInterface;
 use Drupal\Core\Entity\EntityTypeInterface;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Entity\Query\QueryInterface;
+use Drupal\Core\Entity\RevisionableInterface;
 use Drupal\Core\Field\FieldDefinitionInterface;
 use Drupal\Core\Field\FieldStorageDefinitionInterface;
-use Drupal\Core\Entity\RevisionableInterface;
+use Drupal\Driver\Core\Field\AbstractHandler;
 use Drupal\Driver\Core\Field\EntityReferenceRevisionsHandler;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use PHPUnit\Framework\Attributes\Group;
-use PHPUnit\Framework\TestCase;
 
 /**
- * Unit tests for EntityReferenceRevisionsHandler.
- *
- * The handler mirrors EntityReferenceHandler's label-to-id resolution and
- * additionally populates 'target_revision_id' with the current revision id.
- * These tests exercise both the scalar input branch and the extras-array
- * input branch against a mocked entity query + storage.
+ * Tests the EntityReferenceRevisionsHandler field handler.
  *
  * @group fields
  */
 #[Group('fields')]
-class EntityReferenceRevisionsHandlerTest extends TestCase {
+class EntityReferenceRevisionsHandlerTest extends FieldHandlerUnitTestBase {
 
   /**
-   * {@inheritdoc}
+   * Label -> id index for the entity query stub.
+   *
+   * @var array<string, int>
    */
-  protected function tearDown(): void {
-    \Drupal::unsetContainer();
-    parent::tearDown();
-  }
+  protected const KNOWN_LABELS = [
+    'Paragraph A' => 42,
+  ];
 
   /**
-   * Tests that a scalar label resolves to target_id plus target_revision_id.
+   * Revision id every loaded target reports.
    */
-  public function testScalarLabelResolvesToTargetAndRevisionIds(): void {
-    $this->setUpDrupalContainer(resolved_id: 42, revision_id: 7);
+  protected const REVISION_ID = 7;
 
-    $handler = $this->handlerUnderTest();
-    $result = $handler->expand(['Paragraph A']);
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
 
-    $this->assertSame([['target_id' => 42, 'target_revision_id' => 7]], $result);
+    $container = new ContainerBuilder();
+    $container->set('entity_type.manager', $this->createEntityTypeManager(self::KNOWN_LABELS, self::REVISION_ID));
+    \Drupal::setContainer($container);
   }
 
   /**
-   * Tests that an extras-array input preserves extras and resolves the target.
+   * {@inheritdoc}
    */
-  public function testExtrasArrayInputPreservesExtras(): void {
-    $this->setUpDrupalContainer(resolved_id: 42, revision_id: 7);
-
-    $handler = $this->handlerUnderTest();
-    $result = $handler->expand([
-      ['target_id' => 'Paragraph A', 'extra' => 'keep-me'],
-    ]);
-
-    $this->assertSame([
-      ['target_id' => 42, 'extra' => 'keep-me', 'target_revision_id' => 7],
-    ], $result);
+  protected function tearDown(): void {
+    \Drupal::unsetContainer();
+    parent::tearDown();
   }
 
   /**
-   * Tests that the handler throws when the target label does not resolve.
+   * {@inheritdoc}
    */
-  public function testUnknownTargetThrows(): void {
-    $this->setUpDrupalContainer(resolved_id: NULL, revision_id: NULL);
+  protected function createHandler(): FieldHandlerInterface {
+    $field_info = $this->createMock(FieldStorageDefinitionInterface::class);
+    $field_info->method('getSetting')
+      ->with('target_type')
+      ->willReturn('paragraph');
 
-    $handler = $this->handlerUnderTest();
+    $field_config = $this->createMock(FieldDefinitionInterface::class);
+    $field_config->method('getSettings')->willReturn([]);
 
-    $this->expectException(\Exception::class);
-    $this->expectExceptionMessage("No entity 'Paragraph A' of type 'paragraph' exists.");
+    $reflection = new \ReflectionClass(EntityReferenceRevisionsHandler::class);
+    $handler = $reflection->newInstanceWithoutConstructor();
 
-    $handler->expand(['Paragraph A']);
-  }
+    $info_property = new \ReflectionProperty(EntityReferenceRevisionsHandler::class, 'fieldInfo');
+    $info_property->setValue($handler, $field_info);
 
-  /**
-   * Tests that a non-revisionable target yields a NULL revision id.
-   */
-  public function testNonRevisionableTargetYieldsNullRevisionId(): void {
-    $this->setUpDrupalContainer(resolved_id: 42, revision_id: NULL, revisionable: FALSE);
+    $config_property = new \ReflectionProperty(EntityReferenceRevisionsHandler::class, 'fieldConfig');
+    $config_property->setValue($handler, $field_config);
 
-    $handler = $this->handlerUnderTest();
-    $result = $handler->expand(['Paragraph A']);
+    $main_property = new \ReflectionProperty(AbstractHandler::class, 'mainProperty');
+    $main_property->setValue($handler, 'target_id');
 
-    $this->assertSame([['target_id' => 42, 'target_revision_id' => NULL]], $result);
+    return $handler;
   }
 
   /**
-   * Instantiates the handler without invoking its parent constructor.
-   *
-   * Direct construction would bootstrap the field-storage validation in
-   * AbstractHandler, which this test replaces with injected fakes via
-   * reflection. Using reflection keeps the test focused on expand() output.
+   * {@inheritdoc}
    */
-  protected function handlerUnderTest(): EntityReferenceRevisionsHandler {
-    $storage = $this->createMock(FieldStorageDefinitionInterface::class);
-    $storage->method('getSetting')->with('target_type')->willReturn('paragraph');
-    $storage->method('getMainPropertyName')->willReturn('target_id');
-
-    $config = $this->createMock(FieldDefinitionInterface::class);
-    $config->method('getSettings')->willReturn([]);
-
-    $reflection = new \ReflectionClass(EntityReferenceRevisionsHandler::class);
-    $handler = $reflection->newInstanceWithoutConstructor();
-    $info_prop = $reflection->getParentClass()->getProperty('fieldInfo');
-    $info_prop->setValue($handler, $storage);
-    $config_prop = $reflection->getParentClass()->getProperty('fieldConfig');
-    $config_prop->setValue($handler, $config);
-
-    return $handler;
+  public static function dataProviderExpand(): \Iterator {
+    yield 'bare label resolves to id and revision id' => [
+      'Paragraph A',
+      [['target_id' => 42, 'target_revision_id' => self::REVISION_ID]],
+      NULL,
+      NULL,
+    ];
+    yield 'record preserves extras and resolves target' => [
+      [['target_id' => 'Paragraph A', 'extra' => 'keep-me']],
+      [['target_id' => 42, 'extra' => 'keep-me', 'target_revision_id' => self::REVISION_ID]],
+      NULL,
+      NULL,
+    ];
+    yield 'integer id bypasses validation query' => [
+      [99],
+      [['target_id' => 99, 'target_revision_id' => self::REVISION_ID]],
+      NULL,
+      NULL,
+    ];
+
+    yield 'unknown label throws' => [
+      ['Paragraph X'],
+      NULL,
+      \Exception::class,
+      "No entity 'Paragraph X' of type 'paragraph' exists.",
+    ];
   }
 
   /**
-   * Sets up the Drupal container with stubs the handler consults.
+   * Builds the entity_type.manager + query + storage stubs.
    *
-   * The handler calls '\Drupal::entityTypeManager()' and
-   * '\Drupal::entityQuery()', both resolved through '\Drupal::getContainer()'.
-   * Wire the container so the query returns a deterministic id (or an empty
-   * array to force the "not found" branch) and storage returns an optionally
-   * revisionable target.
+   * @param array<string, int> $known_labels
+   *   Label-to-id index.
+   * @param int $revision_id
+   *   Revision id every loaded target reports.
    */
-  protected function setUpDrupalContainer(?int $resolved_id, ?int $revision_id, bool $revisionable = TRUE): void {
-    $query = $this->createMock(QueryInterface::class);
-    $query->method('accessCheck')->willReturnSelf();
-    $query->method('condition')->willReturnSelf();
-    $query->method('orConditionGroup')->willReturn($query);
-    $query->method('execute')->willReturn($resolved_id === NULL ? [] : [$resolved_id => $resolved_id]);
-
-    if ($revisionable) {
-      $target = $this->createMock(RevisionableInterface::class);
-      $target->method('getRevisionId')->willReturn($revision_id);
-    }
-    else {
-      $target = $this->createMock(EntityTypeInterface::class);
-    }
-
-    $entity_storage = $this->createMock(EntityStorageInterface::class);
-    $entity_storage->method('load')->willReturn($target);
-    $entity_storage->method('getQuery')->willReturn($query);
-
+  protected function createEntityTypeManager(array $known_labels, int $revision_id): object {
     $entity_type = $this->createMock(EntityTypeInterface::class);
     $entity_type->method('getKey')->willReturnMap([
       ['id', 'id'],
@@ -151,13 +133,51 @@ protected function setUpDrupalContainer(?int $resolved_id, ?int $revision_id, bo
       ['bundle', 'type'],
     ]);
 
+    $target = $this->createMock(RevisionableInterface::class);
+    $target->method('getRevisionId')->willReturn($revision_id);
+
+    $query = $this->createQueryStub($known_labels);
+
+    $storage = $this->createMock(EntityStorageInterface::class);
+    $storage->method('getQuery')->willReturn($query);
+    $storage->method('load')->willReturn($target);
+
     $entity_type_manager = $this->createMock(EntityTypeManagerInterface::class);
-    $entity_type_manager->method('getDefinition')->with('paragraph')->willReturn($entity_type);
-    $entity_type_manager->method('getStorage')->with('paragraph')->willReturn($entity_storage);
+    $entity_type_manager->method('getDefinition')->willReturn($entity_type);
+    $entity_type_manager->method('getStorage')->willReturn($storage);
 
-    $container = new ContainerBuilder();
-    $container->set('entity_type.manager', $entity_type_manager);
-    \Drupal::setContainer($container);
+    return $entity_type_manager;
+  }
+
+  /**
+   * Builds an entity query mock backed by the label-to-id index.
+   *
+   * @param array<string, int> $known_labels
+   *   Label-to-id index.
+   */
+  protected function createQueryStub(array $known_labels): QueryInterface {
+    $query = $this->createMock(QueryInterface::class);
+    $query->method('accessCheck')->willReturnSelf();
+    $query->method('orConditionGroup')->willReturnSelf();
+
+    $captured_label = NULL;
+    $query->method('condition')
+      ->willReturnCallback(function (mixed $field, mixed $value = NULL) use ($query, &$captured_label): MockObject {
+        if (is_string($field) && in_array($field, ['name', 'title', 'label'], TRUE) && $value !== NULL) {
+          $captured_label = (string) $value;
+        }
+
+        return $query;
+      });
+
+    $query->method('execute')
+      ->willReturnCallback(function () use (&$captured_label, $known_labels): array {
+        return $captured_label !== NULL && isset($known_labels[$captured_label])
+          ? [$known_labels[$captured_label]]
+          : [];
+      });
+
+    return $query;
   }
 
 }
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/FieldHandlerUnitTestBase.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/FieldHandlerUnitTestBase.php
new file mode 100644
index 00000000..bbb1afb6
--- /dev/null
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/FieldHandlerUnitTestBase.php
@@ -0,0 +1,80 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\Driver\Unit\Core\Field;
+
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Base unit test for field handlers.
+ *
+ * Subclasses supply 'createHandler()' and 'dataProviderExpand()'.
+ *
+ * Data provider rows have the shape:
+ *   [input, expected, exception_class_or_NULL, exception_message_or_NULL]
+ *
+ *   - On the happy path: 'expected' is the asserted storage shape;
+ *     'exception_class' is NULL.
+ *   - On the error path: 'expected' is NULL and 'exception_class' is the
+ *     class that must be thrown ('exception_message' optionally pins a
+ *     substring).
+ */
+abstract class FieldHandlerUnitTestBase extends TestCase {
+
+  /**
+   * Produces the configured handler under test.
+   */
+  abstract protected function createHandler(): FieldHandlerInterface;
+
+  /**
+   * Tests 'expand()' end-to-end with caller-shaped input.
+   *
+   * @param mixed $input
+   *   The loose input fed to 'expand()'.
+   * @param mixed $expected
+   *   The expected storage-shape output, or NULL when an exception is
+   *   expected.
+   * @param string|null $exception
+   *   The expected exception class, or NULL for the happy path.
+   * @param string|null $exception_message
+   *   Substring the exception message must contain, or NULL.
+   *
+   * @dataProvider dataProviderExpand
+   */
+  #[DataProvider('dataProviderExpand')]
+  public function testExpand(mixed $input, mixed $expected, ?string $exception, ?string $exception_message): void {
+    $handler = $this->createHandler();
+
+    if ($exception !== NULL) {
+      $this->expectException($exception);
+
+      if ($exception_message !== NULL) {
+        $this->expectExceptionMessage($exception_message);
+      }
+    }
+
+    // Only suppress PHP warnings on rows that expect an exception (e.g.
+    // 'file_get_contents()' raises a warning before the handler throws);
+    // success-path rows must not silently swallow unexpected warnings.
+    $result = $exception !== NULL
+      ? @$handler->expand($input)
+      : $handler->expand($input);
+
+    if ($exception === NULL) {
+      $this->assertSame($expected, $result);
+    }
+  }
+
+  /**
+   * Data provider for 'testExpand()'.
+   *
+   * @return \Iterator<string, array{mixed, mixed, ?string, ?string}>
+   *   Rows of: input, expected storage shape, exception class, message
+   *   substring.
+   */
+  abstract public static function dataProviderExpand(): \Iterator;
+
+}
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/FileHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/FileHandlerTest.php
index b2aa06ca..b85c09d0 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/FileHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/FileHandlerTest.php
@@ -5,10 +5,10 @@
 namespace Drupal\Tests\Driver\Unit\Core\Field;
 
 use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\Driver\Core\Field\AbstractHandler;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use Drupal\Driver\Core\Field\FileHandler;
-use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\Attributes\Group;
-use PHPUnit\Framework\Attributes\DataProvider;
 
 /**
  * Tests the FileHandler field handler.
@@ -16,217 +16,145 @@
  * @group fields
  */
 #[Group('fields')]
-class FileHandlerTest extends TestCase {
+class FileHandlerTest extends FieldHandlerUnitTestBase {
 
   /**
-   * Restores the Drupal container after each test.
+   * Absolute path to the bundled fixture file.
    */
-  protected function tearDown(): void {
-    \Drupal::unsetContainer();
-    parent::tearDown();
-  }
+  protected const FIXTURE_PATH = __DIR__ . '/../../../../../../fixtures/files/fixture.bin';
 
   /**
-   * Tests that unreadable files throw a descriptive exception.
+   * File id 'file.repository::writeData()' returns from the upload-path stub.
    */
-  public function testExpandThrowsWhenFileCannotBeRead(): void {
-    $handler = $this->createHandler();
-    $this->setServicesWithNoMatchingFile();
-
-    $this->expectException(\Exception::class);
-    $this->expectExceptionMessage('Error reading file /tmp/drupal-driver-nonexistent-file.bin.');
-
-    @$handler->expand(['/tmp/drupal-driver-nonexistent-file.bin']);
-  }
+  protected const UPLOADED_FILE_ID = 42;
 
   /**
-   * Tests every accepted input shape on the upload code path.
-   *
-   * Covers the parser shapes that 'EntityFieldParser' emits:
-   *   - Scalar single ('['foo.bin']') and scalar multi-value.
-   *   - Compound mode (['target_id' => 'foo.bin', 'display' => 1, ...]).
-   *
-   * @param \Closure(string): array<int|string, mixed> $build_input
-   *   Builds the input array given the temp file path.
-   * @param array<int, array<string, mixed>> $expected
-   *   The expected expand() output (always a list of records for FileHandler).
+   * Storage stub maps these public-scheme URIs to file ids for the reuse path.
    *
-   * @dataProvider dataProviderExpandUploadsFile
+   * @var array<string, int>
    */
-  #[DataProvider('dataProviderExpandUploadsFile')]
-  public function testExpandUploadsFile(\Closure $build_input, array $expected): void {
-    $path = $this->createTempFile('pdf');
-    $this->setServicesWithUploadReturnId(42);
+  protected const REGISTERED_FILES = [
+    'public://logo.png' => 88,
+    'public://hero.jpg' => 99,
+    'private://secret.pdf' => 444,
+  ];
 
-    $handler = $this->createHandler();
-
-    $result = $handler->expand($build_input($path));
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
 
-    $this->assertSame($expected, $result);
+    $container = new ContainerBuilder();
+    $container->set('entity_type.manager', $this->createEntityTypeManager(self::REGISTERED_FILES));
+    $container->set('file.repository', $this->createFileRepository(self::UPLOADED_FILE_ID));
+    \Drupal::setContainer($container);
   }
 
   /**
-   * Data provider for testExpandUploadsFile().
+   * {@inheritdoc}
    */
-  public static function dataProviderExpandUploadsFile(): \Iterator {
-    yield 'scalar single' => [
-      static fn (string $path): array => [$path],
-      [['target_id' => 42, 'display' => 1, 'description' => '']],
-    ];
-    yield 'scalar multi-value' => [
-      static fn (string $path): array => [$path, $path],
-      [
-        ['target_id' => 42, 'display' => 1, 'description' => ''],
-        ['target_id' => 42, 'display' => 1, 'description' => ''],
-      ],
-    ];
-    yield 'compound single with display and description' => [
-      static fn (string $path): array => [
-        ['target_id' => $path, 'display' => 0, 'description' => 'Spec sheet'],
-      ],
-      [['target_id' => 42, 'display' => 0, 'description' => 'Spec sheet']],
-    ];
-    yield 'compound single, bare target_id' => [
-      static fn (string $path): array => [['target_id' => $path]],
-      [['target_id' => 42, 'display' => 1, 'description' => '']],
-    ];
-    yield 'compound multi-record' => [
-      static fn (string $path): array => [
-        ['target_id' => $path, 'display' => 1, 'description' => 'Public'],
-        ['target_id' => $path, 'display' => 0, 'description' => 'Hidden'],
-      ],
-      [
-        ['target_id' => 42, 'display' => 1, 'description' => 'Public'],
-        ['target_id' => 42, 'display' => 0, 'description' => 'Hidden'],
-      ],
-    ];
+  protected function tearDown(): void {
+    \Drupal::unsetContainer();
+    parent::tearDown();
   }
 
   /**
-   * Tests every accepted input shape on the reuse-existing-managed-file path.
-   *
-   * @param string $managed_uri
-   *   URI of the pre-existing managed File the storage stub will return.
-   * @param int $file_id
-   *   ID of the pre-existing managed File.
-   * @param array<int|string, mixed> $input
-   *   The input passed to expand().
-   * @param array<int, array<string, mixed>> $expected
-   *   The expected expand() output.
-   *
-   * @dataProvider dataProviderExpandReusesManagedFile
+   * {@inheritdoc}
    */
-  #[DataProvider('dataProviderExpandReusesManagedFile')]
-  public function testExpandReusesManagedFile(string $managed_uri, int $file_id, array $input, array $expected): void {
-    $this->setServicesWithMatchingManagedFile(uri: $managed_uri, file_id: $file_id);
-
-    $handler = $this->createHandler();
+  protected function createHandler(): FieldHandlerInterface {
+    $reflection = new \ReflectionClass(FileHandler::class);
+    $handler = $reflection->newInstanceWithoutConstructor();
 
-    $result = $handler->expand($input);
+    $main_property = new \ReflectionProperty(AbstractHandler::class, 'mainProperty');
+    $main_property->setValue($handler, 'target_id');
 
-    $this->assertSame($expected, $result);
+    return $handler;
   }
 
   /**
-   * Data provider for testExpandReusesManagedFile().
+   * {@inheritdoc}
    */
-  public static function dataProviderExpandReusesManagedFile(): \Iterator {
-    yield 'scalar full uri reuse' => [
-      'public://logo.png',
-      77,
+  public static function dataProviderExpand(): \Iterator {
+    yield 'bare scalar path triggers upload' => [
+      self::FIXTURE_PATH,
+      [['target_id' => self::UPLOADED_FILE_ID, 'display' => 1, 'description' => '']],
+      NULL,
+      NULL,
+    ];
+    yield 'list of paths triggers upload' => [
+      [self::FIXTURE_PATH, self::FIXTURE_PATH],
+      [
+        ['target_id' => self::UPLOADED_FILE_ID, 'display' => 1, 'description' => ''],
+        ['target_id' => self::UPLOADED_FILE_ID, 'display' => 1, 'description' => ''],
+      ],
+      NULL,
+      NULL,
+    ];
+    yield 'record with display and description preserved' => [
+      [['target_id' => self::FIXTURE_PATH, 'display' => 0, 'description' => 'Spec sheet']],
+      [['target_id' => self::UPLOADED_FILE_ID, 'display' => 0, 'description' => 'Spec sheet']],
+      NULL,
+      NULL,
+    ];
+    yield 'known public-scheme URI reuses managed file' => [
       ['public://logo.png'],
-      [['target_id' => 77, 'display' => 1, 'description' => '']],
+      [['target_id' => 88, 'display' => 1, 'description' => '']],
+      NULL,
+      NULL,
     ];
-    yield 'scalar bare basename, public scheme' => [
-      'public://report.pdf',
-      123,
-      ['report.pdf'],
-      [['target_id' => 123, 'display' => 1, 'description' => '']],
+    yield 'bare basename resolves under public://' => [
+      ['logo.png'],
+      [['target_id' => 88, 'display' => 1, 'description' => '']],
+      NULL,
+      NULL,
     ];
-    yield 'scalar bare basename, private scheme fallback' => [
-      'private://secret.pdf',
-      444,
+    yield 'bare basename falls through to private://' => [
       ['secret.pdf'],
       [['target_id' => 444, 'display' => 1, 'description' => '']],
+      NULL,
+      NULL,
     ];
-    yield 'compound parser shape, uri reuse' => [
-      'public://logo.png',
-      80,
+    yield 'record reusing managed file by URI' => [
       [['target_id' => 'public://logo.png', 'display' => 0, 'description' => 'Brand mark']],
-      [['target_id' => 80, 'display' => 0, 'description' => 'Brand mark']],
-    ];
-    yield 'compound parser shape, bare basename reuse' => [
-      'public://report.pdf',
-      90,
-      [['target_id' => 'report.pdf']],
-      [['target_id' => 90, 'display' => 1, 'description' => '']],
+      [['target_id' => 88, 'display' => 0, 'description' => 'Brand mark']],
+      NULL,
+      NULL,
     ];
-  }
-
-  /**
-   * Creates a FileHandler that bypasses the parent constructor.
-   */
-  protected function createHandler(): FileHandler {
-    $reflection = new \ReflectionClass(FileHandler::class);
-    return $reflection->newInstanceWithoutConstructor();
-  }
-
-  /**
-   * Creates a temporary file and returns its path.
-   */
-  protected function createTempFile(string $extension): string {
-    $path = tempnam(sys_get_temp_dir(), 'drupal-driver-') . '.' . $extension;
-    file_put_contents($path, 'fixture');
-    return $path;
-  }
 
-  /**
-   * Sets up services such that no existing managed file matches any lookup.
-   */
-  protected function setServicesWithNoMatchingFile(): void {
-    $container = new ContainerBuilder();
-    $container->set('entity_type.manager', $this->createEntityTypeManagerReturningNoMatches());
-    \Drupal::setContainer($container);
-  }
-
-  /**
-   * Sets up services for the upload-path branch.
-   *
-   * No managed file matches the lookup; file.repository returns a new File
-   * with the given ID.
-   */
-  protected function setServicesWithUploadReturnId(int $file_id): void {
-    $container = new ContainerBuilder();
-    $container->set('entity_type.manager', $this->createEntityTypeManagerReturningNoMatches());
-    $container->set('file.repository', $this->createFileRepositoryReturning($this->createFakeFile($file_id)));
-    \Drupal::setContainer($container);
-  }
-
-  /**
-   * Sets up services for the resolve-path branch: managed file matches at URI.
-   */
-  protected function setServicesWithMatchingManagedFile(string $uri, int $file_id): void {
-    $container = new ContainerBuilder();
-    $container->set(
-      'entity_type.manager',
-      $this->createEntityTypeManagerReturningFileAtUri($uri, $this->createFakeFile($file_id)),
-    );
-    \Drupal::setContainer($container);
+    yield 'NULL target_id rejected by normalise' => [
+      [['target_id' => NULL]],
+      NULL,
+      \InvalidArgumentException::class,
+      'File field "target_id" must not be NULL or empty.',
+    ];
+    yield 'empty target_id rejected by normalise' => [
+      [['target_id' => '']],
+      NULL,
+      \InvalidArgumentException::class,
+      'File field "target_id" must not be NULL or empty.',
+    ];
+    yield 'unreadable path bubbles up as Exception' => [
+      ['/tmp/drupal-driver-nonexistent-file.bin'],
+      NULL,
+      \Exception::class,
+      'Error reading file /tmp/drupal-driver-nonexistent-file.bin.',
+    ];
   }
 
   /**
-   * Creates a stand-in File entity that exposes an id() method.
+   * Builds a fake File entity exposing 'id()'.
    */
-  protected function createFakeFile(int $file_id): object {
-    return new class($file_id) {
+  protected static function createFakeFile(int $id): object {
+    return new class($id) {
 
-      public function __construct(protected readonly int $fileId) {}
+      public function __construct(protected readonly int $id) {}
 
       /**
-       * Returns the stored file entity ID.
+       * Returns the configured file entity id.
        */
       public function id(): int {
-        return $this->fileId;
+        return $this->id;
       }
 
       /**
@@ -239,15 +167,17 @@ public function save(): void {
   }
 
   /**
-   * Creates a stand-in file.repository service returning the given file.
+   * Builds a file.repository stub returning a fresh File on writeData().
    */
-  protected function createFileRepositoryReturning(object $file): object {
+  protected function createFileRepository(int $upload_id): object {
+    $file = self::createFakeFile($upload_id);
+
     return new class($file) {
 
       public function __construct(protected readonly object $file) {}
 
       /**
-       * Returns the pre-configured stored file.
+       * Returns the configured file entity for any write.
        */
       public function writeData(string $data, string $destination): object {
         return $this->file;
@@ -257,66 +187,41 @@ public function writeData(string $data, string $destination): object {
   }
 
   /**
-   * Creates a stand-in entity_type.manager whose file storage never matches.
+   * Builds an entity_type.manager stub for the file storage lookup branch.
+   *
+   * @param array<string, int> $registered_files
+   *   Map of URI to file id; anything outside the map produces no match.
    */
-  protected function createEntityTypeManagerReturningNoMatches(): object {
-    $storage = new class {
+  protected function createEntityTypeManager(array $registered_files): object {
+    $files_by_uri = [];
 
-      /**
-       * Returns an empty match list for every lookup.
-       *
-       * @param array<string, string> $properties
-       *   The lookup properties (ignored in this stub).
-       *
-       * @return array<int, object>
-       *   Always an empty array.
-       */
-      public function loadByProperties(array $properties): array {
-        return [];
-      }
+    foreach ($registered_files as $uri => $id) {
+      $files_by_uri[$uri] = self::createFakeFile($id);
+    }
 
-    };
-
-    return new class($storage) {
-
-      public function __construct(protected readonly object $storage) {}
+    $storage = new class($files_by_uri) {
 
       /**
-       * Returns the stub file storage.
+       * @param array<string, object> $files_by_uri
+       *   Files keyed by URI.
        */
-      public function getStorage(string $entity_type_id): object {
-        return $this->storage;
-      }
-
-    };
-  }
-
-  /**
-   * Creates an entity_type.manager stub whose file storage matches one URI.
-   *
-   * The storage's loadByProperties() returns $file only when called with
-   * exactly ['uri' => $uri], and an empty array for every other lookup.
-   */
-  protected function createEntityTypeManagerReturningFileAtUri(string $uri, object $file): object {
-    $storage = new class($uri, $file) {
-
-      public function __construct(protected readonly string $uri, protected readonly object $file) {}
+      public function __construct(protected readonly array $files_by_uri) {}
 
       /**
-       * Returns the configured file only for lookups matching the stored URI.
+       * Returns the file matching the given URI, or an empty list.
        *
        * @param array<string, string> $properties
-       *   The loadByProperties() input keyed by property name.
+       *   Lookup properties keyed by name.
        *
        * @return array<int, object>
-       *   Either a single-element list with the configured file, or empty.
+       *   Single-element list when matched, empty otherwise.
        */
       public function loadByProperties(array $properties): array {
-        if (($properties['uri'] ?? NULL) === $this->uri) {
-          return [$this->file];
-        }
+        $uri = $properties['uri'] ?? NULL;
 
-        return [];
+        return $uri !== NULL && isset($this->files_by_uri[$uri])
+          ? [$this->files_by_uri[$uri]]
+          : [];
       }
 
     };
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/ImageHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/ImageHandlerTest.php
index b54725d5..a923c92a 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/ImageHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/ImageHandlerTest.php
@@ -6,10 +6,9 @@
 
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Driver\Core\Field\AbstractHandler;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use Drupal\Driver\Core\Field\ImageHandler;
-use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\Attributes\Group;
-use PHPUnit\Framework\Attributes\DataProvider;
 
 /**
  * Tests the ImageHandler field handler.
@@ -17,250 +16,138 @@
  * @group fields
  */
 #[Group('fields')]
-class ImageHandlerTest extends TestCase {
+class ImageHandlerTest extends FieldHandlerUnitTestBase {
 
   /**
-   * {@inheritdoc}
+   * Absolute path to the bundled fixture file.
    */
-  protected function tearDown(): void {
-    \Drupal::unsetContainer();
-    parent::tearDown();
-  }
+  protected const FIXTURE_PATH = __DIR__ . '/../../../../../../fixtures/files/fixture.bin';
 
   /**
-   * Tests that unreadable files throw a descriptive exception.
+   * File id 'file.repository::writeData()' returns from the upload-path stub.
    */
-  public function testExpandThrowsWhenFileCannotBeRead(): void {
-    $handler = $this->createHandler();
-    $this->setServicesWithNoMatchingFile();
-
-    $this->expectException(\Exception::class);
-    $this->expectExceptionMessage('Error reading file /tmp/drupal-driver-nonexistent-image.jpg.');
-
-    @$handler->expand('/tmp/drupal-driver-nonexistent-image.jpg');
-  }
+  protected const UPLOADED_FILE_ID = 7;
 
   /**
-   * Tests that records with NULL or empty 'target_id' throw clearly.
-   *
-   * The "key missing entirely" case is caught one layer up by
-   * AbstractHandler::normalise(); this test covers the values that get
-   * past key validation but cannot drive file resolution.
+   * Storage stub maps these URIs to file ids for the reuse path.
    *
-   * @param array<int|string, mixed> $input
-   *   The malformed input.
-   *
-   * @dataProvider dataProviderExpandThrowsWhenTargetIdInvalid
+   * @var array<string, int>
    */
-  #[DataProvider('dataProviderExpandThrowsWhenTargetIdInvalid')]
-  public function testExpandThrowsWhenTargetIdInvalid(array $input): void {
-    $handler = $this->createHandler();
+  protected const REGISTERED_FILES = [
+    'public://hero.jpg' => 55,
+    'public://logo.png' => 66,
+  ];
 
-    $this->expectException(\InvalidArgumentException::class);
-    $this->expectExceptionMessage('Image field "target_id" must not be NULL or empty.');
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
 
-    $handler->expand($input);
+    $container = new ContainerBuilder();
+    $container->set('entity_type.manager', $this->createEntityTypeManager(self::REGISTERED_FILES));
+    $container->set('file.repository', $this->createFileRepository(self::UPLOADED_FILE_ID));
+    \Drupal::setContainer($container);
   }
 
   /**
-   * Data provider for testExpandThrowsWhenTargetIdInvalid().
+   * {@inheritdoc}
    */
-  public static function dataProviderExpandThrowsWhenTargetIdInvalid(): \Iterator {
-    yield 'record with NULL target_id' => [
-      ['target_id' => NULL, 'alt' => 'A'],
-    ];
-    yield 'record with empty string target_id' => [
-      ['target_id' => '', 'alt' => 'A'],
-    ];
-    yield 'list with NULL target_id first' => [
-      [['target_id' => NULL, 'alt' => 'orphan'], ['target_id' => 'foo.jpg']],
-    ];
+  protected function tearDown(): void {
+    \Drupal::unsetContainer();
+    parent::tearDown();
   }
 
   /**
-   * Tests every accepted input shape on the upload code path.
-   *
-   * The handler delegates shape normalisation to AbstractHandler::normalise(),
-   * which already has its own dedicated test. This test confirms that every
-   * loose shape arrives at the file-resolution code with the expected
-   * 'target_id' and that extras (alt/title) round-trip when present.
-   *
-   * @param \Closure(string): mixed $build_input
-   *   Builds the input given the temp file path.
-   * @param array<int, array<string, mixed>> $expected
-   *   The expected expand() output (always a list of records).
-   *
-   * @dataProvider dataProviderExpandUploadsFile
+   * {@inheritdoc}
    */
-  #[DataProvider('dataProviderExpandUploadsFile')]
-  public function testExpandUploadsFile(\Closure $build_input, array $expected): void {
-    $path = tempnam(sys_get_temp_dir(), 'drupal-driver-') . '.jpg';
-    file_put_contents($path, 'fixture');
-    $this->setServicesWithUploadReturnId(7);
-
-    $handler = $this->createHandler();
+  protected function createHandler(): FieldHandlerInterface {
+    $reflection = new \ReflectionClass(ImageHandler::class);
+    $handler = $reflection->newInstanceWithoutConstructor();
 
-    $result = $handler->expand($build_input($path));
+    $main_property = new \ReflectionProperty(AbstractHandler::class, 'mainProperty');
+    $main_property->setValue($handler, 'target_id');
 
-    $this->assertSame($expected, $result);
+    return $handler;
   }
 
   /**
-   * Data provider for testExpandUploadsFile().
+   * {@inheritdoc}
    */
-  public static function dataProviderExpandUploadsFile(): \Iterator {
-    yield 'bare scalar path' => [
-      static fn (string $path): string => $path,
-      [['target_id' => 7, 'alt' => NULL, 'title' => NULL]],
+  public static function dataProviderExpand(): \Iterator {
+    yield 'bare scalar path triggers upload' => [
+      self::FIXTURE_PATH,
+      [['target_id' => self::UPLOADED_FILE_ID, 'alt' => NULL, 'title' => NULL]],
+      NULL,
+      NULL,
     ];
-    yield 'list of one scalar path' => [
-      static fn (string $path): array => [$path],
-      [['target_id' => 7, 'alt' => NULL, 'title' => NULL]],
-    ];
-    yield 'list of two scalar paths' => [
-      static fn (string $path): array => [$path, $path],
+    yield 'list of paths triggers upload' => [
+      [self::FIXTURE_PATH, self::FIXTURE_PATH],
       [
-        ['target_id' => 7, 'alt' => NULL, 'title' => NULL],
-        ['target_id' => 7, 'alt' => NULL, 'title' => NULL],
+        ['target_id' => self::UPLOADED_FILE_ID, 'alt' => NULL, 'title' => NULL],
+        ['target_id' => self::UPLOADED_FILE_ID, 'alt' => NULL, 'title' => NULL],
       ],
+      NULL,
+      NULL,
     ];
-    yield 'single record with target_id only' => [
-      static fn (string $path): array => ['target_id' => $path],
-      [['target_id' => 7, 'alt' => NULL, 'title' => NULL]],
+    yield 'record with alt and title preserved' => [
+      [['target_id' => self::FIXTURE_PATH, 'alt' => 'An image', 'title' => 'A title']],
+      [['target_id' => self::UPLOADED_FILE_ID, 'alt' => 'An image', 'title' => 'A title']],
+      NULL,
+      NULL,
     ];
-    yield 'single record with alt and title' => [
-      static fn (string $path): array => ['target_id' => $path, 'alt' => 'An image', 'title' => 'A title'],
-      [['target_id' => 7, 'alt' => 'An image', 'title' => 'A title']],
+    yield 'known URI reuses managed file' => [
+      ['public://hero.jpg'],
+      [['target_id' => 55, 'alt' => NULL, 'title' => NULL]],
+      NULL,
+      NULL,
     ];
-    yield 'list of one record' => [
-      static fn (string $path): array => [['target_id' => $path, 'alt' => 'Solo']],
-      [['target_id' => 7, 'alt' => 'Solo', 'title' => NULL]],
+    yield 'bare basename resolves under public scheme' => [
+      ['logo.png'],
+      [['target_id' => 66, 'alt' => NULL, 'title' => NULL]],
+      NULL,
+      NULL,
     ];
-    yield 'list of multiple records' => [
-      static fn (string $path): array => [
-        ['target_id' => $path, 'alt' => 'First'],
-        ['target_id' => $path, 'alt' => 'Second', 'title' => 'Second title'],
-      ],
-      [
-        ['target_id' => 7, 'alt' => 'First', 'title' => NULL],
-        ['target_id' => 7, 'alt' => 'Second', 'title' => 'Second title'],
-      ],
+    yield 'record reusing managed file by URI with extras' => [
+      [['target_id' => 'public://hero.jpg', 'alt' => 'Hero', 'title' => 'Hero title']],
+      [['target_id' => 55, 'alt' => 'Hero', 'title' => 'Hero title']],
+      NULL,
+      NULL,
     ];
-  }
-
-  /**
-   * Tests every accepted input shape on the reuse-existing-managed-file path.
-   *
-   * @param string $managed_uri
-   *   URI of the pre-existing managed File the storage stub will return.
-   * @param int $file_id
-   *   ID of the pre-existing managed File.
-   * @param mixed $input
-   *   The input passed to expand() (any of the loose shapes the consumer
-   *   can naturally produce).
-   * @param array<int, array<string, mixed>> $expected
-   *   The expected expand() output.
-   *
-   * @dataProvider dataProviderExpandReusesManagedFile
-   */
-  #[DataProvider('dataProviderExpandReusesManagedFile')]
-  public function testExpandReusesManagedFile(string $managed_uri, int $file_id, mixed $input, array $expected): void {
-    $this->setServicesWithMatchingManagedFile(uri: $managed_uri, file_id: $file_id);
-
-    $handler = $this->createHandler();
-
-    $result = $handler->expand($input);
-
-    $this->assertSame($expected, $result);
-  }
 
-  /**
-   * Data provider for testExpandReusesManagedFile().
-   */
-  public static function dataProviderExpandReusesManagedFile(): \Iterator {
-    yield 'bare scalar uri' => [
-      'public://hero.jpg',
-      55,
-      'public://hero.jpg',
-      [['target_id' => 55, 'alt' => NULL, 'title' => NULL]],
+    yield 'NULL target_id rejected' => [
+      [['target_id' => NULL, 'alt' => 'A']],
+      NULL,
+      \InvalidArgumentException::class,
+      'Image field "target_id" must not be NULL or empty.',
     ];
-    yield 'bare scalar basename' => [
-      'public://logo.png',
-      66,
-      'logo.png',
-      [['target_id' => 66, 'alt' => NULL, 'title' => NULL]],
-    ];
-    yield 'single record with uri and extras' => [
-      'public://hero.jpg',
-      77,
-      ['target_id' => 'public://hero.jpg', 'alt' => 'Hero', 'title' => 'Hero title'],
-      [['target_id' => 77, 'alt' => 'Hero', 'title' => 'Hero title']],
+    yield 'empty target_id rejected' => [
+      [['target_id' => '', 'alt' => 'A']],
+      NULL,
+      \InvalidArgumentException::class,
+      'Image field "target_id" must not be NULL or empty.',
     ];
-    yield 'list of one record with basename' => [
-      'public://logo.png',
-      88,
-      [['target_id' => 'logo.png']],
-      [['target_id' => 88, 'alt' => NULL, 'title' => NULL]],
+    yield 'unreadable path bubbles up as Exception' => [
+      ['/tmp/drupal-driver-nonexistent-image.jpg'],
+      NULL,
+      \Exception::class,
+      'Error reading file /tmp/drupal-driver-nonexistent-image.jpg.',
     ];
   }
 
   /**
-   * Creates an ImageHandler with the main property injected.
-   */
-  protected function createHandler(): ImageHandler {
-    $reflection = new \ReflectionClass(ImageHandler::class);
-    $handler = $reflection->newInstanceWithoutConstructor();
-
-    $property = new \ReflectionProperty(AbstractHandler::class, 'mainProperty');
-    $property->setValue($handler, 'target_id');
-
-    return $handler;
-  }
-
-  /**
-   * Sets up services such that no existing managed file matches any lookup.
+   * Builds a fake File entity exposing 'id()'.
    */
-  protected function setServicesWithNoMatchingFile(): void {
-    $container = new ContainerBuilder();
-    $container->set('entity_type.manager', $this->createEntityTypeManagerReturningNoMatches());
-    \Drupal::setContainer($container);
-  }
+  protected static function createFakeFile(int $id): object {
+    return new class($id) {
 
-  /**
-   * Sets up services for the upload-path branch.
-   */
-  protected function setServicesWithUploadReturnId(int $file_id): void {
-    $container = new ContainerBuilder();
-    $container->set('entity_type.manager', $this->createEntityTypeManagerReturningNoMatches());
-    $container->set('file.repository', $this->createFileRepositoryReturning($this->createFakeFile($file_id)));
-    \Drupal::setContainer($container);
-  }
-
-  /**
-   * Sets up services for the resolve-path branch.
-   */
-  protected function setServicesWithMatchingManagedFile(string $uri, int $file_id): void {
-    $container = new ContainerBuilder();
-    $container->set(
-      'entity_type.manager',
-      $this->createEntityTypeManagerReturningFileAtUri($uri, $this->createFakeFile($file_id)),
-    );
-    \Drupal::setContainer($container);
-  }
-
-  /**
-   * Creates a stand-in File entity that exposes an id() method.
-   */
-  protected function createFakeFile(int $file_id): object {
-    return new class($file_id) {
-
-      public function __construct(protected readonly int $fileId) {}
+      public function __construct(protected readonly int $id) {}
 
       /**
-       * Returns the stored file entity ID.
+       * Returns the configured file entity id.
        */
       public function id(): int {
-        return $this->fileId;
+        return $this->id;
       }
 
       /**
@@ -273,15 +160,17 @@ public function save(): void {
   }
 
   /**
-   * Creates a stand-in file.repository service returning the given file.
+   * Builds a file.repository stub returning a fresh File on writeData().
    */
-  protected function createFileRepositoryReturning(object $file): object {
+  protected function createFileRepository(int $upload_id): object {
+    $file = self::createFakeFile($upload_id);
+
     return new class($file) {
 
       public function __construct(protected readonly object $file) {}
 
       /**
-       * Returns the pre-configured stored file.
+       * Returns the configured file entity for any write.
        */
       public function writeData(string $data, string $destination): object {
         return $this->file;
@@ -291,66 +180,41 @@ public function writeData(string $data, string $destination): object {
   }
 
   /**
-   * Creates a stand-in entity_type.manager whose file storage never matches.
+   * Builds an entity_type.manager stub for the file storage lookup branch.
+   *
+   * @param array<string, int> $registered_files
+   *   Map of URI to file id; anything outside the map produces no match.
    */
-  protected function createEntityTypeManagerReturningNoMatches(): object {
-    $storage = new class {
+  protected function createEntityTypeManager(array $registered_files): object {
+    $files_by_uri = [];
 
-      /**
-       * Returns an empty match list for every lookup.
-       *
-       * @param array<string, string> $properties
-       *   The lookup properties (ignored in this stub).
-       *
-       * @return array<int, object>
-       *   Always an empty array.
-       */
-      public function loadByProperties(array $properties): array {
-        return [];
-      }
-
-    };
-
-    return new class($storage) {
+    foreach ($registered_files as $uri => $id) {
+      $files_by_uri[$uri] = self::createFakeFile($id);
+    }
 
-      public function __construct(protected readonly object $storage) {}
+    $storage = new class($files_by_uri) {
 
       /**
-       * Returns the stub file storage.
+       * @param array<string, object> $files_by_uri
+       *   Files keyed by URI.
        */
-      public function getStorage(string $entity_type_id): object {
-        return $this->storage;
-      }
-
-    };
-  }
-
-  /**
-   * Creates an entity_type.manager stub whose file storage matches one URI.
-   *
-   * The storage's loadByProperties() returns $file only when called with
-   * exactly ['uri' => $uri], and an empty array for every other lookup.
-   */
-  protected function createEntityTypeManagerReturningFileAtUri(string $uri, object $file): object {
-    $storage = new class($uri, $file) {
-
-      public function __construct(protected readonly string $uri, protected readonly object $file) {}
+      public function __construct(protected readonly array $files_by_uri) {}
 
       /**
-       * Returns the configured file only for lookups matching the stored URI.
+       * Returns the file matching the given URI, or an empty list.
        *
        * @param array<string, string> $properties
-       *   The loadByProperties() input keyed by property name.
+       *   Lookup properties keyed by name.
        *
        * @return array<int, object>
-       *   Either a single-element list with the configured file, or empty.
+       *   Single-element list when matched, empty otherwise.
        */
       public function loadByProperties(array $properties): array {
-        if (($properties['uri'] ?? NULL) === $this->uri) {
-          return [$this->file];
-        }
+        $uri = $properties['uri'] ?? NULL;
 
-        return [];
+        return $uri !== NULL && isset($this->files_by_uri[$uri])
+          ? [$this->files_by_uri[$uri]]
+          : [];
       }
 
     };
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/LinkHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/LinkHandlerTest.php
index 8abb2ca0..da1436d3 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/LinkHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/LinkHandlerTest.php
@@ -4,10 +4,9 @@
 
 namespace Drupal\Tests\Driver\Unit\Core\Field;
 
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use Drupal\Driver\Core\Field\LinkHandler;
-use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\Attributes\Group;
-use PHPUnit\Framework\Attributes\DataProvider;
 
 /**
  * Tests the LinkHandler field handler.
@@ -15,89 +14,85 @@
  * @group fields
  */
 #[Group('fields')]
-class LinkHandlerTest extends TestCase {
+class LinkHandlerTest extends FieldHandlerUnitTestBase {
 
   /**
- * Tests link field expansion.
- *
- * @param array<int, mixed> $input
- *   The input values to expand.
- * @param array<int, mixed> $expected
- *   The expected expanded values.
- *
- * @dataProvider dataProviderExpand
- */
-  #[DataProvider('dataProviderExpand')]
-  public function testExpand(array $input, array $expected): void {
-    $handler = $this->createHandler();
-    $result = $handler->expand($input);
-    $this->assertSame($expected, $result);
+   * {@inheritdoc}
+   */
+  protected function createHandler(): FieldHandlerInterface {
+    return (new \ReflectionClass(LinkHandler::class))->newInstanceWithoutConstructor();
   }
 
   /**
-   * Data provider for testExpand().
+   * {@inheritdoc}
    */
   public static function dataProviderExpand(): \Iterator {
-    yield 'numeric indices' => [
-        [['My link', 'https://example.com']],
-        [['title' => 'My link', 'uri' => 'https://example.com', 'options' => []]],
-    ];
-    yield 'named keys' => [
-        [['title' => 'My link', 'uri' => 'https://example.com']],
-        [['title' => 'My link', 'uri' => 'https://example.com', 'options' => []]],
+    yield 'uri only via list' => [
+      ['https://example.com'],
+      [['uri' => 'https://example.com', 'options' => []]],
+      NULL,
+      NULL,
     ];
-    yield 'numeric indices with options' => [
-        [['My link', 'https://example.com', 'target=_blank&rel=nofollow']],
-        [[
-          'title' => 'My link',
-          'uri' => 'https://example.com',
-          'options' => ['target' => '_blank', 'rel' => 'nofollow'],
-        ],
-        ],
+    yield 'positional title and uri' => [
+      [['My link', 'https://example.com']],
+      [['title' => 'My link', 'uri' => 'https://example.com', 'options' => []]],
+      NULL,
+      NULL,
     ];
-    yield 'named keys with options' => [
-        [['title' => 'My link', 'uri' => 'https://example.com', 'options' => 'target=_blank']],
-        [['title' => 'My link', 'uri' => 'https://example.com', 'options' => ['target' => '_blank']]],
+    yield 'positional with options query string' => [
+      [['My link', 'https://example.com', 'target=_blank&rel=nofollow']],
+      [[
+        'title' => 'My link',
+        'uri' => 'https://example.com',
+        'options' => ['target' => '_blank', 'rel' => 'nofollow'],
+      ],
+      ],
+      NULL,
+      NULL,
     ];
-    yield 'multiple values' => [
-        [
-          ['First', 'https://first.com'],
-          ['title' => 'Second', 'uri' => 'https://second.com'],
-        ],
-        [
-          ['title' => 'First', 'uri' => 'https://first.com', 'options' => []],
-          ['title' => 'Second', 'uri' => 'https://second.com', 'options' => []],
-        ],
+    yield 'keyed record' => [
+      [['title' => 'My link', 'uri' => 'https://example.com']],
+      [['title' => 'My link', 'uri' => 'https://example.com', 'options' => []]],
+      NULL,
+      NULL,
     ];
-    yield 'no options returns empty array' => [
-        [['title' => 'Link', 'uri' => 'https://example.com']],
-        [['title' => 'Link', 'uri' => 'https://example.com', 'options' => []]],
+    yield 'keyed record with options string' => [
+      [['title' => 'My link', 'uri' => 'https://example.com', 'options' => 'target=_blank']],
+      [['title' => 'My link', 'uri' => 'https://example.com', 'options' => ['target' => '_blank']]],
+      NULL,
+      NULL,
     ];
-    yield 'uri-only string' => [
-        ['https://example.com'],
-        [['uri' => 'https://example.com', 'options' => []]],
+    yield 'keyed record with options array' => [
+      [['title' => 'My link', 'uri' => 'https://example.com', 'options' => ['target' => '_blank']]],
+      [['title' => 'My link', 'uri' => 'https://example.com', 'options' => ['target' => '_blank']]],
+      NULL,
+      NULL,
     ];
-    yield 'mixed uri-only and full' => [
-        [
-          'https://first.com',
-          ['title' => 'Second', 'uri' => 'https://second.com'],
-        ],
-        [
-          ['uri' => 'https://first.com', 'options' => []],
-          ['title' => 'Second', 'uri' => 'https://second.com', 'options' => []],
-        ],
+    yield 'multi-delta mixed shapes' => [
+      [
+        'https://first.com',
+        ['title' => 'Second', 'uri' => 'https://second.com'],
+      ],
+      [
+        ['uri' => 'https://first.com', 'options' => []],
+        ['title' => 'Second', 'uri' => 'https://second.com', 'options' => []],
+      ],
+      NULL,
+      NULL,
     ];
-  }
 
-  /**
-   * Creates a LinkHandler instance that bypasses the parent constructor.
-   *
-   * @return \Drupal\Driver\Core\Field\LinkHandler
-   *   The handler instance.
-   */
-  protected function createHandler(): LinkHandler {
-    $reflection = new \ReflectionClass(LinkHandler::class);
-    return $reflection->newInstanceWithoutConstructor();
+    yield 'top-level mixed positional and named keys rejected' => [
+      ['https://first.com', 'title' => 'Mixed'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Link field value cannot mix positional and named keys',
+    ];
+    yield 'record missing uri rejected' => [
+      [['title' => 'No URI']],
+      NULL,
+      \InvalidArgumentException::class,
+      'Link field record must include a uri',
+    ];
   }
 
 }
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/ListFloatHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/ListFloatHandlerTest.php
new file mode 100644
index 00000000..7f9795ed
--- /dev/null
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/ListFloatHandlerTest.php
@@ -0,0 +1,70 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\Driver\Unit\Core\Field;
+
+use Drupal\Core\Field\FieldStorageDefinitionInterface;
+use Drupal\Driver\Core\Field\AbstractHandler;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
+use Drupal\Driver\Core\Field\ListFloatHandler;
+use PHPUnit\Framework\Attributes\Group;
+
+/**
+ * Tests the ListFloatHandler field handler.
+ *
+ * @group fields
+ */
+#[Group('fields')]
+class ListFloatHandlerTest extends FieldHandlerUnitTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function createHandler(): FieldHandlerInterface {
+    $field_info = $this->createMock(FieldStorageDefinitionInterface::class);
+    $field_info->method('getSetting')
+      ->with('allowed_values')
+      ->willReturn([
+        '1.5' => 'One and a half',
+        '2.5' => 'Two and a half',
+      ]);
+
+    $reflection = new \ReflectionClass(ListFloatHandler::class);
+    $handler = $reflection->newInstanceWithoutConstructor();
+
+    $info_property = new \ReflectionProperty(ListFloatHandler::class, 'fieldInfo');
+    $info_property->setValue($handler, $field_info);
+
+    $main_property = new \ReflectionProperty(AbstractHandler::class, 'mainProperty');
+    $main_property->setValue($handler, 'value');
+
+    return $handler;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function dataProviderExpand(): \Iterator {
+    yield 'label resolves to float key' => [
+      ['One and a half'],
+      [1.5],
+      NULL,
+      NULL,
+    ];
+    yield 'unmatched value passes through' => [
+      ['Unknown'],
+      ['Unknown'],
+      NULL,
+      NULL,
+    ];
+
+    yield 'record missing main property rejected' => [
+      ['unexpected' => 'oops'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field record must include the main property "value"',
+    ];
+  }
+
+}
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/ListHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/ListHandlerTest.php
deleted file mode 100644
index bb54c645..00000000
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/ListHandlerTest.php
+++ /dev/null
@@ -1,106 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Drupal\Tests\Driver\Unit\Core\Field;
-
-use Drupal\Core\Field\FieldStorageDefinitionInterface;
-use Drupal\Driver\Core\Field\ListFloatHandler;
-use Drupal\Driver\Core\Field\ListIntegerHandler;
-use Drupal\Driver\Core\Field\ListStringHandler;
-use PHPUnit\Framework\TestCase;
-use PHPUnit\Framework\Attributes\Group;
-
-/**
- * Tests the List* field handlers (shared ListHandlerBase logic).
- *
- * @group fields
- */
-#[Group('fields')]
-class ListHandlerTest extends TestCase {
-
-  /**
-   * Tests that values matching allowed_values labels are mapped to keys.
-   */
-  public function testExpandMapsLabelsToKeys(): void {
-    $handler = $this->createHandler(ListStringHandler::class, [
-      'red' => 'Red',
-      'green' => 'Green',
-      'blue' => 'Blue',
-    ]);
-
-    $this->assertSame(['green', 'blue'], $handler->expand(['Green', 'Blue']));
-  }
-
-  /**
-   * Tests that unmatched values fall through unchanged.
-   */
-  public function testExpandReturnsOriginalValuesWhenNoMatch(): void {
-    $handler = $this->createHandler(ListStringHandler::class, [
-      'a' => 'Alpha',
-    ]);
-
-    $this->assertSame(['Unknown'], $handler->expand(['Unknown']));
-  }
-
-  /**
-   * Tests that integer list values are mapped to keys.
-   */
-  public function testIntegerListMapsLabelsToKeys(): void {
-    $handler = $this->createHandler(ListIntegerHandler::class, [
-      1 => 'One',
-      2 => 'Two',
-    ]);
-
-    $this->assertSame([2], $handler->expand(['Two']));
-  }
-
-  /**
-   * Tests that float list values are mapped to keys.
-   */
-  public function testFloatListMapsLabelsToKeys(): void {
-    $handler = $this->createHandler(ListFloatHandler::class, [
-      '1.5' => 'One and a half',
-    ]);
-
-    $this->assertSame(['1.5'], $handler->expand(['One and a half']));
-  }
-
-  /**
-   * Tests that a scalar value is cast to an array before lookup.
-   */
-  public function testExpandCastsScalarToArray(): void {
-    $handler = $this->createHandler(ListStringHandler::class, [
-      'k' => 'Label',
-    ]);
-
-    $this->assertSame(['k'], $handler->expand('Label'));
-  }
-
-  /**
-   * Creates a list handler with an injected field storage definition.
-   *
-   * @param string $class_name
-   *   The handler class to instantiate.
-   * @param array<string, string> $allowed_values
-   *   The allowed_values map to inject via the fieldInfo setting.
-   *
-   * @return object
-   *   The handler instance with fieldInfo populated.
-   */
-  protected function createHandler(string $class_name, array $allowed_values): object {
-    $field_info = $this->createMock(FieldStorageDefinitionInterface::class);
-    $field_info->method('getSetting')
-      ->with('allowed_values')
-      ->willReturn($allowed_values);
-
-    $reflection = new \ReflectionClass($class_name);
-    $handler = $reflection->newInstanceWithoutConstructor();
-
-    $property = new \ReflectionProperty($class_name, 'fieldInfo');
-    $property->setValue($handler, $field_info);
-
-    return $handler;
-  }
-
-}
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/ListIntegerHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/ListIntegerHandlerTest.php
new file mode 100644
index 00000000..59331e29
--- /dev/null
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/ListIntegerHandlerTest.php
@@ -0,0 +1,70 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\Driver\Unit\Core\Field;
+
+use Drupal\Core\Field\FieldStorageDefinitionInterface;
+use Drupal\Driver\Core\Field\AbstractHandler;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
+use Drupal\Driver\Core\Field\ListIntegerHandler;
+use PHPUnit\Framework\Attributes\Group;
+
+/**
+ * Tests the ListIntegerHandler field handler.
+ *
+ * @group fields
+ */
+#[Group('fields')]
+class ListIntegerHandlerTest extends FieldHandlerUnitTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function createHandler(): FieldHandlerInterface {
+    $field_info = $this->createMock(FieldStorageDefinitionInterface::class);
+    $field_info->method('getSetting')
+      ->with('allowed_values')
+      ->willReturn([
+        1 => 'One',
+        2 => 'Two',
+      ]);
+
+    $reflection = new \ReflectionClass(ListIntegerHandler::class);
+    $handler = $reflection->newInstanceWithoutConstructor();
+
+    $info_property = new \ReflectionProperty(ListIntegerHandler::class, 'fieldInfo');
+    $info_property->setValue($handler, $field_info);
+
+    $main_property = new \ReflectionProperty(AbstractHandler::class, 'mainProperty');
+    $main_property->setValue($handler, 'value');
+
+    return $handler;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function dataProviderExpand(): \Iterator {
+    yield 'label resolves to integer key' => [
+      ['Two'],
+      [2],
+      NULL,
+      NULL,
+    ];
+    yield 'unmatched value passes through' => [
+      ['Unknown'],
+      ['Unknown'],
+      NULL,
+      NULL,
+    ];
+
+    yield 'record missing main property rejected' => [
+      ['unexpected' => 'oops'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field record must include the main property "value"',
+    ];
+  }
+
+}
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/ListStringHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/ListStringHandlerTest.php
new file mode 100644
index 00000000..84250181
--- /dev/null
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/ListStringHandlerTest.php
@@ -0,0 +1,83 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\Tests\Driver\Unit\Core\Field;
+
+use Drupal\Core\Field\FieldStorageDefinitionInterface;
+use Drupal\Driver\Core\Field\AbstractHandler;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
+use Drupal\Driver\Core\Field\ListStringHandler;
+use PHPUnit\Framework\Attributes\Group;
+
+/**
+ * Tests the ListStringHandler field handler.
+ *
+ * @group fields
+ */
+#[Group('fields')]
+class ListStringHandlerTest extends FieldHandlerUnitTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function createHandler(): FieldHandlerInterface {
+    $field_info = $this->createMock(FieldStorageDefinitionInterface::class);
+    $field_info->method('getSetting')
+      ->with('allowed_values')
+      ->willReturn([
+        'red' => 'Red',
+        'green' => 'Green',
+        'blue' => 'Blue',
+      ]);
+
+    $reflection = new \ReflectionClass(ListStringHandler::class);
+    $handler = $reflection->newInstanceWithoutConstructor();
+
+    $info_property = new \ReflectionProperty(ListStringHandler::class, 'fieldInfo');
+    $info_property->setValue($handler, $field_info);
+
+    $main_property = new \ReflectionProperty(AbstractHandler::class, 'mainProperty');
+    $main_property->setValue($handler, 'value');
+
+    return $handler;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function dataProviderExpand(): \Iterator {
+    yield 'list of labels mapped to keys' => [
+      ['Green', 'Blue'],
+      ['green', 'blue'],
+      NULL,
+      NULL,
+    ];
+    yield 'unmatched value passes through' => [
+      ['Unknown'],
+      ['Unknown'],
+      NULL,
+      NULL,
+    ];
+    yield 'scalar label resolves to key' => [
+      'Red',
+      ['red'],
+      NULL,
+      NULL,
+    ];
+
+    yield 'mixed positional and named keys rejected' => [
+      ['Red', 'extra' => 'oops'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field value cannot mix positional and named keys',
+    ];
+    yield 'record missing main property rejected' => [
+      ['unexpected' => 'oops'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field record must include the main property "value"',
+    ];
+  }
+
+}
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/NameHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/NameHandlerTest.php
index b6da6f96..a908416b 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/NameHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/NameHandlerTest.php
@@ -5,10 +5,9 @@
 namespace Drupal\Tests\Driver\Unit\Core\Field;
 
 use Drupal\Core\Field\FieldDefinitionInterface;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use Drupal\Driver\Core\Field\NameHandler;
-use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\Attributes\Group;
-use PHPUnit\Framework\TestCase;
 
 /**
  * Tests the NameHandler field handler.
@@ -16,7 +15,7 @@
  * @group fields
  */
 #[Group('fields')]
-class NameHandlerTest extends TestCase {
+class NameHandlerTest extends FieldHandlerUnitTestBase {
 
   /**
    * All six name components, all enabled (the module's default).
@@ -33,43 +32,47 @@ class NameHandlerTest extends TestCase {
   ];
 
   /**
-   * Tests name field expansion with all components enabled.
-   *
-   * @param array<int, mixed> $input
-   *   The input values to expand.
-   * @param array<int, mixed> $expected
-   *   The expected expanded values.
-   *
-   * @dataProvider dataProviderExpand
+   * {@inheritdoc}
    */
-  #[DataProvider('dataProviderExpand')]
-  public function testExpand(array $input, array $expected): void {
-    $handler = $this->createHandler();
-    $result = $handler->expand($input);
-    $this->assertSame($expected, $result);
+  protected function createHandler(): FieldHandlerInterface {
+    return $this->createHandlerWithComponents(self::ALL_ENABLED);
   }
 
   /**
-   * Data provider for testExpand().
+   * {@inheritdoc}
    */
   public static function dataProviderExpand(): \Iterator {
-    yield 'string shorthand family, given' => [
-      ['Doe, John'],
+    yield 'family-only shorthand string' => [
+      'Doe',
+      [['family' => 'Doe', 'given' => NULL]],
+      NULL,
+      NULL,
+    ];
+    yield 'family-given shorthand string' => [
+      'Doe, John',
       [['family' => 'Doe', 'given' => 'John']],
+      NULL,
+      NULL,
     ];
-    yield 'string shorthand family only' => [
-      ['Doe'],
-      [['family' => 'Doe', 'given' => NULL]],
+    yield 'list with shorthand string' => [
+      ['Doe, John'],
+      [['family' => 'Doe', 'given' => 'John']],
+      NULL,
+      NULL,
     ];
-    yield 'named keys' => [
+    yield 'list with single keyed record' => [
       [['given' => 'John', 'family' => 'Doe', 'middle' => 'Q']],
       [['given' => 'John', 'family' => 'Doe', 'middle' => 'Q']],
+      NULL,
+      NULL,
     ];
-    yield 'numeric indices' => [
+    yield 'list with positional array' => [
       [['Dr', 'John', 'Quincy', 'Doe']],
       [['title' => 'Dr', 'given' => 'John', 'middle' => 'Quincy', 'family' => 'Doe']],
+      NULL,
+      NULL,
     ];
-    yield 'multiple values' => [
+    yield 'multi-delta mixed shorthand and keyed' => [
       [
         'Doe, John',
         ['given' => 'Jane', 'family' => 'Smith'],
@@ -78,14 +81,29 @@ public static function dataProviderExpand(): \Iterator {
         ['family' => 'Doe', 'given' => 'John'],
         ['given' => 'Jane', 'family' => 'Smith'],
       ],
+      NULL,
+      NULL,
+    ];
+
+    yield 'mixed numeric and named keys rejected' => [
+      [['John', 'family' => 'Smith']],
+      NULL,
+      \RuntimeException::class,
+      'Cannot mix numeric and named keys in the same name value',
+    ];
+    yield 'unknown sub-field key rejected' => [
+      [['nickname' => 'Johnny']],
+      NULL,
+      \RuntimeException::class,
+      'Invalid name sub-field key: nickname.',
     ];
   }
 
   /**
-   * Tests that numeric indices skip components disabled on the field.
+   * Tests that positional indices skip components disabled on the field.
    */
   public function testNumericIndicesSkipDisabledComponents(): void {
-    $handler = $this->createHandler([
+    $handler = $this->createHandlerWithComponents([
       NameHandler::COMPONENT_TITLE => TRUE,
       NameHandler::COMPONENT_GIVEN => TRUE,
       NameHandler::COMPONENT_MIDDLE => FALSE,
@@ -94,18 +112,17 @@ public function testNumericIndicesSkipDisabledComponents(): void {
       NameHandler::COMPONENT_CREDENTIALS => FALSE,
     ]);
 
-    $result = $handler->expand([['Dr', 'John', 'Doe']]);
-
-    $this->assertSame([
-      ['title' => 'Dr', 'given' => 'John', 'family' => 'Doe'],
-    ], $result);
+    $this->assertSame(
+      [['title' => 'Dr', 'given' => 'John', 'family' => 'Doe']],
+      $handler->expand([['Dr', 'John', 'Doe']]),
+    );
   }
 
   /**
-   * Tests that excess numeric indices throw.
+   * Tests that excess positional indices throw.
    */
   public function testTooManyNumericIndicesThrows(): void {
-    $handler = $this->createHandler([
+    $handler = $this->createHandlerWithComponents([
       NameHandler::COMPONENT_TITLE => FALSE,
       NameHandler::COMPONENT_GIVEN => TRUE,
       NameHandler::COMPONENT_MIDDLE => FALSE,
@@ -124,7 +141,7 @@ public function testTooManyNumericIndicesThrows(): void {
    * Tests that a named key targeting a disabled component throws.
    */
   public function testNamedKeyForDisabledComponentThrows(): void {
-    $handler = $this->createHandler([
+    $handler = $this->createHandlerWithComponents([
       NameHandler::COMPONENT_TITLE => FALSE,
       NameHandler::COMPONENT_GIVEN => TRUE,
       NameHandler::COMPONENT_MIDDLE => FALSE,
@@ -140,34 +157,10 @@ public function testNamedKeyForDisabledComponentThrows(): void {
   }
 
   /**
-   * Tests that mixing numeric and named keys in one delta throws.
-   */
-  public function testMixedNumericAndNamedKeysThrows(): void {
-    $handler = $this->createHandler();
-
-    $this->expectException(\RuntimeException::class);
-    $this->expectExceptionMessage('Cannot mix numeric and named keys in the same name value; use one shape consistently.');
-
-    $handler->expand([['John', 'family' => 'Smith']]);
-  }
-
-  /**
-   * Tests that an unknown sub-field key throws.
-   */
-  public function testUnknownKeyThrows(): void {
-    $handler = $this->createHandler();
-
-    $this->expectException(\RuntimeException::class);
-    $this->expectExceptionMessage('Invalid name sub-field key: nickname.');
-
-    $handler->expand([['nickname' => 'Johnny']]);
-  }
-
-  /**
-   * Tests that the shorthand throws when family is disabled.
+   * Tests that the shorthand throws when 'family' is disabled.
    */
   public function testShorthandThrowsWhenFamilyDisabled(): void {
-    $handler = $this->createHandler([
+    $handler = $this->createHandlerWithComponents([
       NameHandler::COMPONENT_TITLE => TRUE,
       NameHandler::COMPONENT_GIVEN => TRUE,
       NameHandler::COMPONENT_MIDDLE => FALSE,
@@ -179,14 +172,14 @@ public function testShorthandThrowsWhenFamilyDisabled(): void {
     $this->expectException(\RuntimeException::class);
     $this->expectExceptionMessage('Cannot use the "Family, Given" shorthand because the "family" component is disabled on this field.');
 
-    $handler->expand(['Doe, John']);
+    $handler->expand('Doe, John');
   }
 
   /**
    * Tests that the shorthand throws when a given part is supplied but disabled.
    */
   public function testShorthandThrowsWhenGivenPartSuppliedButDisabled(): void {
-    $handler = $this->createHandler([
+    $handler = $this->createHandlerWithComponents([
       NameHandler::COMPONENT_TITLE => FALSE,
       NameHandler::COMPONENT_GIVEN => FALSE,
       NameHandler::COMPONENT_MIDDLE => FALSE,
@@ -198,14 +191,14 @@ public function testShorthandThrowsWhenGivenPartSuppliedButDisabled(): void {
     $this->expectException(\RuntimeException::class);
     $this->expectExceptionMessage('Cannot use the "Family, Given" shorthand because the "given" component is disabled on this field.');
 
-    $handler->expand(['Doe, John']);
+    $handler->expand('Doe, John');
   }
 
   /**
    * Tests the family-only shorthand when 'given' is disabled.
    */
   public function testShorthandFamilyOnlyWhenGivenDisabled(): void {
-    $handler = $this->createHandler([
+    $handler = $this->createHandlerWithComponents([
       NameHandler::COMPONENT_TITLE => FALSE,
       NameHandler::COMPONENT_GIVEN => FALSE,
       NameHandler::COMPONENT_MIDDLE => FALSE,
@@ -214,21 +207,16 @@ public function testShorthandFamilyOnlyWhenGivenDisabled(): void {
       NameHandler::COMPONENT_CREDENTIALS => FALSE,
     ]);
 
-    $result = $handler->expand(['Doe']);
-
-    $this->assertSame([['family' => 'Doe']], $result);
+    $this->assertSame([['family' => 'Doe']], $handler->expand('Doe'));
   }
 
   /**
-   * Creates a NameHandler with an injected fieldConfig mock.
+   * Creates a NameHandler with the given components map injected.
    *
    * @param array<string, bool> $components
-   *   Map of component name to enabled flag. Defaults to all enabled.
-   *
-   * @return \Drupal\Driver\Core\Field\NameHandler
-   *   The handler instance.
+   *   Map of component name to enabled flag.
    */
-  protected function createHandler(array $components = self::ALL_ENABLED): NameHandler {
+  protected function createHandlerWithComponents(array $components): NameHandler {
     $field_config = $this->createMock(FieldDefinitionInterface::class);
     $field_config->method('getSettings')->willReturn(['components' => $components]);
 
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/SmartdateHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/SmartdateHandlerTest.php
index 15b8b4d2..504cf40a 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/SmartdateHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/SmartdateHandlerTest.php
@@ -4,10 +4,9 @@
 
 namespace Drupal\Tests\Driver\Unit\Core\Field;
 
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use Drupal\Driver\Core\Field\SmartdateHandler;
-use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\Attributes\Group;
-use PHPUnit\Framework\Attributes\DataProvider;
 
 /**
  * Tests the SmartdateHandler field handler.
@@ -15,71 +14,62 @@
  * @group fields
  */
 #[Group('fields')]
-class SmartdateHandlerTest extends TestCase {
+class SmartdateHandlerTest extends FieldHandlerUnitTestBase {
 
   /**
-   * Tests smartdate field expansion.
-   *
-   * @param mixed $input
-   *   The input values to expand.
-   * @param array<int, array<string, mixed>> $expected
-   *   The expected expanded records.
-   *
-   * @dataProvider dataProviderExpand
+   * {@inheritdoc}
    */
-  #[DataProvider('dataProviderExpand')]
-  public function testExpand(mixed $input, array $expected): void {
-    $handler = $this->createHandler();
-    $result = $handler->expand($input);
-    $this->assertSame($expected, $result);
+  protected function createHandler(): FieldHandlerInterface {
+    return (new \ReflectionClass(SmartdateHandler::class))->newInstanceWithoutConstructor();
   }
 
   /**
-   * Data provider for testExpand().
+   * {@inheritdoc}
    */
   public static function dataProviderExpand(): \Iterator {
     // 2026-07-15T09:00:00 UTC = 1784106000.
-    // 2026-07-15T17:00:00 UTC = 1784134800.
-    // Duration: (1784134800 - 1784106000) / 60 = 480 minutes.
+    // 2026-07-15T17:00:00 UTC = 1784134800. Duration: 480 minutes.
     yield 'empty array returns empty list' => [
       [],
       [],
+      NULL,
+      NULL,
     ];
-
-    yield 'non-array input returns empty list' => [
+    yield 'non-array returns empty list' => [
       'not-an-array',
       [],
+      NULL,
+      NULL,
     ];
-
     yield 'single positional pair' => [
       [1784106000, 1784134800],
-      [
-        [
-          'value' => 1784106000,
-          'end_value' => 1784134800,
-          'duration' => 480,
-          'rrule' => NULL,
-          'rrule_index' => NULL,
-          'timezone' => '',
-        ],
+      [[
+        'value' => 1784106000,
+        'end_value' => 1784134800,
+        'duration' => 480,
+        'rrule' => NULL,
+        'rrule_index' => NULL,
+        'timezone' => '',
+      ],
       ],
+      NULL,
+      NULL,
     ];
-
-    yield 'single named record' => [
+    yield 'single keyed record' => [
       ['value' => 1784106000, 'end_value' => 1784134800],
-      [
-        [
-          'value' => 1784106000,
-          'end_value' => 1784134800,
-          'duration' => 480,
-          'rrule' => NULL,
-          'rrule_index' => NULL,
-          'timezone' => '',
-        ],
+      [[
+        'value' => 1784106000,
+        'end_value' => 1784134800,
+        'duration' => 480,
+        'rrule' => NULL,
+        'rrule_index' => NULL,
+        'timezone' => '',
       ],
+      ],
+      NULL,
+      NULL,
     ];
-
-    yield 'list of named records (multi-delta)' => [
+    yield 'list of keyed records' => [
       [
         ['value' => 1784106000, 'end_value' => 1784134800],
         ['value' => 1784790000, 'end_value' => 1784818800],
@@ -102,78 +92,79 @@ public static function dataProviderExpand(): \Iterator {
           'timezone' => '',
         ],
       ],
+      NULL,
+      NULL,
     ];
-
-    yield 'explicit duration overrides auto-computed' => [
+    yield 'explicit duration overrides derived' => [
       ['value' => 1784106000, 'end_value' => 1784134800, 'duration' => 999],
-      [
-        [
-          'value' => 1784106000,
-          'end_value' => 1784134800,
-          'duration' => 999,
-          'rrule' => NULL,
-          'rrule_index' => NULL,
-          'timezone' => '',
-        ],
+      [[
+        'value' => 1784106000,
+        'end_value' => 1784134800,
+        'duration' => 999,
+        'rrule' => NULL,
+        'rrule_index' => NULL,
+        'timezone' => '',
+      ],
       ],
+      NULL,
+      NULL,
     ];
-
-    yield 'duration defaults to zero when only start provided' => [
+    yield 'NULL end yields zero duration' => [
       ['value' => 1784106000],
-      [
-        [
-          'value' => 1784106000,
-          'end_value' => NULL,
-          'duration' => 0,
-          'rrule' => NULL,
-          'rrule_index' => NULL,
-          'timezone' => '',
-        ],
+      [[
+        'value' => 1784106000,
+        'end_value' => NULL,
+        'duration' => 0,
+        'rrule' => NULL,
+        'rrule_index' => NULL,
+        'timezone' => '',
+      ],
       ],
+      NULL,
+      NULL,
     ];
-
     yield 'NULL endpoints preserved' => [
       ['value' => NULL, 'end_value' => NULL],
-      [
-        [
-          'value' => NULL,
-          'end_value' => NULL,
-          'duration' => 0,
-          'rrule' => NULL,
-          'rrule_index' => NULL,
-          'timezone' => '',
-        ],
+      [[
+        'value' => NULL,
+        'end_value' => NULL,
+        'duration' => 0,
+        'rrule' => NULL,
+        'rrule_index' => NULL,
+        'timezone' => '',
+      ],
       ],
+      NULL,
+      NULL,
     ];
-
     yield 'end before start clamps duration to zero' => [
       ['value' => 1784134800, 'end_value' => 1784106000],
-      [
-        [
-          'value' => 1784134800,
-          'end_value' => 1784106000,
-          'duration' => 0,
-          'rrule' => NULL,
-          'rrule_index' => NULL,
-          'timezone' => '',
-        ],
+      [[
+        'value' => 1784134800,
+        'end_value' => 1784106000,
+        'duration' => 0,
+        'rrule' => NULL,
+        'rrule_index' => NULL,
+        'timezone' => '',
+      ],
       ],
+      NULL,
+      NULL,
     ];
-
     yield 'date string parsed via strtotime' => [
       ['value' => '2026-07-15T09:00:00 UTC', 'end_value' => '2026-07-15T17:00:00 UTC'],
-      [
-        [
-          'value' => 1784106000,
-          'end_value' => 1784134800,
-          'duration' => 480,
-          'rrule' => NULL,
-          'rrule_index' => NULL,
-          'timezone' => '',
-        ],
+      [[
+        'value' => 1784106000,
+        'end_value' => 1784134800,
+        'duration' => 480,
+        'rrule' => NULL,
+        'rrule_index' => NULL,
+        'timezone' => '',
       ],
+      ],
+      NULL,
+      NULL,
     ];
-
     yield 'rrule, rrule_index and timezone passed through' => [
       [
         'value' => 1784106000,
@@ -182,71 +173,56 @@ public static function dataProviderExpand(): \Iterator {
         'rrule_index' => 3,
         'timezone' => 'Australia/Sydney',
       ],
-      [
-        [
-          'value' => 1784106000,
-          'end_value' => 1784134800,
-          'duration' => 480,
-          'rrule' => 42,
-          'rrule_index' => 3,
-          'timezone' => 'Australia/Sydney',
-        ],
+      [[
+        'value' => 1784106000,
+        'end_value' => 1784134800,
+        'duration' => 480,
+        'rrule' => 42,
+        'rrule_index' => 3,
+        'timezone' => 'Australia/Sydney',
+      ],
       ],
+      NULL,
+      NULL,
     ];
-
     yield 'unparseable string becomes NULL' => [
       ['value' => 'not a date', 'end_value' => NULL],
-      [
-        [
-          'value' => NULL,
-          'end_value' => NULL,
-          'duration' => 0,
-          'rrule' => NULL,
-          'rrule_index' => NULL,
-          'timezone' => '',
-        ],
+      [[
+        'value' => NULL,
+        'end_value' => NULL,
+        'duration' => 0,
+        'rrule' => NULL,
+        'rrule_index' => NULL,
+        'timezone' => '',
+      ],
       ],
+      NULL,
+      NULL,
     ];
-
     yield 'numeric string timestamp cast to int' => [
       ['value' => '1784106000', 'end_value' => '1784134800'],
-      [
-        [
-          'value' => 1784106000,
-          'end_value' => 1784134800,
-          'duration' => 480,
-          'rrule' => NULL,
-          'rrule_index' => NULL,
-          'timezone' => '',
-        ],
+      [[
+        'value' => 1784106000,
+        'end_value' => 1784134800,
+        'duration' => 480,
+        'rrule' => NULL,
+        'rrule_index' => NULL,
+        'timezone' => '',
       ],
+      ],
+      NULL,
+      NULL,
     ];
 
-    yield 'non-array record in list is skipped' => [
+    yield 'non-array delta in list rejected' => [
       [
         ['value' => 1784106000, 'end_value' => 1784134800],
         'not-a-record',
       ],
-      [
-        [
-          'value' => 1784106000,
-          'end_value' => 1784134800,
-          'duration' => 480,
-          'rrule' => NULL,
-          'rrule_index' => NULL,
-          'timezone' => '',
-        ],
-      ],
+      NULL,
+      \InvalidArgumentException::class,
+      'Smartdate field delta must be an array',
     ];
   }
 
-  /**
-   * Creates a SmartdateHandler instance that bypasses the parent constructor.
-   */
-  protected function createHandler(): SmartdateHandler {
-    $reflection = new \ReflectionClass(SmartdateHandler::class);
-
-    return $reflection->newInstanceWithoutConstructor();
-  }
-
 }
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/SupportedImageHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/SupportedImageHandlerTest.php
index 6e51c32f..442c17e3 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/SupportedImageHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/SupportedImageHandlerTest.php
@@ -5,8 +5,9 @@
 namespace Drupal\Tests\Driver\Unit\Core\Field;
 
 use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\Driver\Core\Field\AbstractHandler;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use Drupal\Driver\Core\Field\SupportedImageHandler;
-use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\Attributes\Group;
 
 /**
@@ -15,7 +16,28 @@
  * @group fields
  */
 #[Group('fields')]
-class SupportedImageHandlerTest extends TestCase {
+class SupportedImageHandlerTest extends FieldHandlerUnitTestBase {
+
+  /**
+   * Absolute path to the bundled fixture file.
+   */
+  protected const FIXTURE_PATH = __DIR__ . '/../../../../../../fixtures/files/fixture.bin';
+
+  /**
+   * File id 'file.repository::writeData()' returns from the stub.
+   */
+  protected const UPLOADED_FILE_ID = 3;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+
+    $container = new ContainerBuilder();
+    $container->set('file.repository', $this->createFileRepository(self::UPLOADED_FILE_ID));
+    \Drupal::setContainer($container);
+  }
 
   /**
    * {@inheritdoc}
@@ -26,31 +48,26 @@ protected function tearDown(): void {
   }
 
   /**
-   * Tests that unreadable files throw a descriptive exception.
+   * {@inheritdoc}
    */
-  public function testExpandThrowsWhenFileCannotBeRead(): void {
-    $handler = $this->createHandler();
+  protected function createHandler(): FieldHandlerInterface {
+    $reflection = new \ReflectionClass(SupportedImageHandler::class);
+    $handler = $reflection->newInstanceWithoutConstructor();
 
-    $this->expectException(\Exception::class);
-    $this->expectExceptionMessage('Error reading file');
+    $main_property = new \ReflectionProperty(AbstractHandler::class, 'mainProperty');
+    $main_property->setValue($handler, 'target_id');
 
-    @$handler->expand('/tmp/drupal-driver-nonexistent-supported-image.jpg');
+    return $handler;
   }
 
   /**
-   * Tests that a string input is normalised into a single-item result.
+   * {@inheritdoc}
    */
-  public function testExpandNormalisesStringInputToSingleItem(): void {
-    $path = $this->createTempFile('jpg');
-    $this->setFileRepositoryWithReturnId(3);
-
-    $handler = $this->createHandler();
-
-    $result = $handler->expand($path);
-
-    $this->assertSame([
-      [
-        'target_id' => 3,
+  public static function dataProviderExpand(): \Iterator {
+    yield 'bare scalar path produces full record' => [
+      self::FIXTURE_PATH,
+      [[
+        'target_id' => self::UPLOADED_FILE_ID,
         'alt' => NULL,
         'title' => NULL,
         'caption_value' => NULL,
@@ -58,21 +75,13 @@ public function testExpandNormalisesStringInputToSingleItem(): void {
         'attribution_value' => NULL,
         'attribution_format' => NULL,
       ],
-    ], $result);
-  }
-
-  /**
-   * Tests that caption and attribution metadata are preserved.
-   */
-  public function testExpandPreservesCaptionAndAttributionMetadata(): void {
-    $path = $this->createTempFile('png');
-    $this->setFileRepositoryWithReturnId(5);
-
-    $handler = $this->createHandler();
-
-    $result = $handler->expand([
-      [
-        'target_id' => $path,
+      ],
+      NULL,
+      NULL,
+    ];
+    yield 'record preserves caption and attribution metadata' => [
+      [[
+        'target_id' => self::FIXTURE_PATH,
         'alt' => 'Alt',
         'title' => 'Title',
         'caption_value' => 'Caption body',
@@ -80,11 +89,9 @@ public function testExpandPreservesCaptionAndAttributionMetadata(): void {
         'attribution_value' => 'Photographer',
         'attribution_format' => 'plain_text',
       ],
-    ]);
-
-    $this->assertSame([
-      [
-        'target_id' => 5,
+      ],
+      [[
+        'target_id' => self::UPLOADED_FILE_ID,
         'alt' => 'Alt',
         'title' => 'Title',
         'caption_value' => 'Caption body',
@@ -92,62 +99,38 @@ public function testExpandPreservesCaptionAndAttributionMetadata(): void {
         'attribution_value' => 'Photographer',
         'attribution_format' => 'plain_text',
       ],
-    ], $result);
-  }
-
-  /**
-   * Tests that a single array with target_id is wrapped as a single item.
-   */
-  public function testExpandWrapsSingleKeyedArrayInput(): void {
-    $path = $this->createTempFile('jpg');
-    $this->setFileRepositoryWithReturnId(8);
-
-    $handler = $this->createHandler();
-
-    $result = $handler->expand([
-      'target_id' => $path,
-      'alt' => 'An image',
-    ]);
-
-    $this->assertCount(1, $result);
-    $this->assertSame(8, $result[0]['target_id']);
-    $this->assertSame('An image', $result[0]['alt']);
-  }
-
-  /**
-   * Creates a SupportedImageHandler that bypasses the parent constructor.
-   */
-  protected function createHandler(): SupportedImageHandler {
-    $reflection = new \ReflectionClass(SupportedImageHandler::class);
-    return $reflection->newInstanceWithoutConstructor();
-  }
-
-  /**
-   * Creates a temporary file with the given extension.
-   */
-  protected function createTempFile(string $extension): string {
-    $path = tempnam(sys_get_temp_dir(), 'drupal-driver-') . '.' . $extension;
-    file_put_contents($path, 'fixture');
-    return $path;
+      ],
+      NULL,
+      NULL,
+    ];
+
+    yield 'NULL target_id rejected' => [
+      [['target_id' => NULL]],
+      NULL,
+      \InvalidArgumentException::class,
+      'Supported image field "target_id" must not be NULL or empty.',
+    ];
+    yield 'unreadable path bubbles up as Exception' => [
+      '/tmp/drupal-driver-nonexistent-supported-image.jpg',
+      NULL,
+      \Exception::class,
+      'Error reading file /tmp/drupal-driver-nonexistent-supported-image.jpg.',
+    ];
   }
 
   /**
-   * Registers a mocked file.repository service returning a file with an ID.
-   *
-   * Uses inline anonymous classes because FileInterface and
-   * FileRepositoryInterface ship with the file module rather than drupal/core
-   * and are therefore not guaranteed to be autoloadable in isolation.
+   * Builds a fake File entity exposing 'id()'.
    */
-  protected function setFileRepositoryWithReturnId(int $file_id): void {
-    $file = new class($file_id) {
+  protected static function createFakeFile(int $id): object {
+    return new class($id) {
 
-      public function __construct(private readonly int $file_id) {}
+      public function __construct(protected readonly int $id) {}
 
       /**
-       * Returns the stored file entity ID.
+       * Returns the configured file entity id.
        */
       public function id(): int {
-        return $this->file_id;
+        return $this->id;
       }
 
       /**
@@ -157,23 +140,26 @@ public function save(): void {
       }
 
     };
+  }
 
-    $repository = new class($file) {
+  /**
+   * Builds a file.repository stub returning a fresh File on writeData().
+   */
+  protected function createFileRepository(int $upload_id): object {
+    $file = self::createFakeFile($upload_id);
+
+    return new class($file) {
 
-      public function __construct(private readonly mixed $file) {}
+      public function __construct(protected readonly object $file) {}
 
       /**
-       * Writes data to a destination and returns the stored file entity.
+       * Returns the configured file entity for any write.
        */
-      public function writeData(string $data, string $destination): mixed {
+      public function writeData(string $data, string $destination): object {
         return $this->file;
       }
 
     };
-
-    $container = new ContainerBuilder();
-    $container->set('file.repository', $repository);
-    \Drupal::setContainer($container);
   }
 
 }
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/TextHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/TextHandlerTest.php
index 4324fcbd..dadfb4c6 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/TextHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/TextHandlerTest.php
@@ -5,8 +5,8 @@
 namespace Drupal\Tests\Driver\Unit\Core\Field;
 
 use Drupal\Driver\Core\Field\AbstractHandler;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use Drupal\Driver\Core\Field\TextHandler;
-use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\Attributes\Group;
 
 /**
@@ -15,25 +15,12 @@
  * @group fields
  */
 #[Group('fields')]
-class TextHandlerTest extends TestCase {
+class TextHandlerTest extends FieldHandlerUnitTestBase {
 
   /**
-   * Tests that expand() returns a canonical list of records.
+   * {@inheritdoc}
    */
-  public function testExpandReturnsCanonicalRecordList(): void {
-    $handler = $this->createHandler();
-
-    $values = [
-      ['value' => 'Inline text.', 'format' => 'plain_text'],
-    ];
-
-    $this->assertSame($values, $handler->expand($values));
-  }
-
-  /**
-   * Creates a TextHandler with the main property injected.
-   */
-  protected function createHandler(): TextHandler {
+  protected function createHandler(): FieldHandlerInterface {
     $reflection = new \ReflectionClass(TextHandler::class);
     $handler = $reflection->newInstanceWithoutConstructor();
 
@@ -43,4 +30,47 @@ protected function createHandler(): TextHandler {
     return $handler;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public static function dataProviderExpand(): \Iterator {
+    yield 'bare scalar' => [
+      'Inline text.',
+      [['value' => 'Inline text.']],
+      NULL,
+      NULL,
+    ];
+    yield 'list of scalars' => [
+      ['a', 'b'],
+      [['value' => 'a'], ['value' => 'b']],
+      NULL,
+      NULL,
+    ];
+    yield 'single record with value and format' => [
+      ['value' => 'Inline text.', 'format' => 'plain_text'],
+      [['value' => 'Inline text.', 'format' => 'plain_text']],
+      NULL,
+      NULL,
+    ];
+    yield 'list of records' => [
+      [['value' => 'a', 'format' => 'plain_text'], ['value' => 'b']],
+      [['value' => 'a', 'format' => 'plain_text'], ['value' => 'b']],
+      NULL,
+      NULL,
+    ];
+
+    yield 'mixed positional and named keys rejected' => [
+      ['a', 'format' => 'plain_text'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field value cannot mix positional and named keys',
+    ];
+    yield 'record missing main property rejected' => [
+      ['format' => 'plain_text'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field record must include the main property "value"',
+    ];
+  }
+
 }
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/TextLongHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/TextLongHandlerTest.php
index 802c9149..dbc87d29 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/TextLongHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/TextLongHandlerTest.php
@@ -5,8 +5,8 @@
 namespace Drupal\Tests\Driver\Unit\Core\Field;
 
 use Drupal\Driver\Core\Field\AbstractHandler;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use Drupal\Driver\Core\Field\TextLongHandler;
-use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\Attributes\Group;
 
 /**
@@ -15,25 +15,12 @@
  * @group fields
  */
 #[Group('fields')]
-class TextLongHandlerTest extends TestCase {
+class TextLongHandlerTest extends FieldHandlerUnitTestBase {
 
   /**
-   * Tests that expand() returns a canonical list of records.
+   * {@inheritdoc}
    */
-  public function testExpandReturnsCanonicalRecordList(): void {
-    $handler = $this->createHandler();
-
-    $values = [
-      ['value' => 'Body copy.', 'format' => 'plain_text'],
-    ];
-
-    $this->assertSame($values, $handler->expand($values));
-  }
-
-  /**
-   * Creates a TextLongHandler with the main property injected.
-   */
-  protected function createHandler(): TextLongHandler {
+  protected function createHandler(): FieldHandlerInterface {
     $reflection = new \ReflectionClass(TextLongHandler::class);
     $handler = $reflection->newInstanceWithoutConstructor();
 
@@ -43,4 +30,35 @@ protected function createHandler(): TextLongHandler {
     return $handler;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public static function dataProviderExpand(): \Iterator {
+    yield 'bare scalar' => [
+      'Body copy.',
+      [['value' => 'Body copy.']],
+      NULL,
+      NULL,
+    ];
+    yield 'single record with value and format' => [
+      ['value' => 'Body copy.', 'format' => 'plain_text'],
+      [['value' => 'Body copy.', 'format' => 'plain_text']],
+      NULL,
+      NULL,
+    ];
+
+    yield 'mixed positional and named keys rejected' => [
+      ['Body.', 'format' => 'plain_text'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field value cannot mix positional and named keys',
+    ];
+    yield 'record missing main property rejected' => [
+      ['format' => 'plain_text'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field record must include the main property "value"',
+    ];
+  }
+
 }
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/TextWithSummaryHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/TextWithSummaryHandlerTest.php
index 86dabbd8..df7eeec6 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/TextWithSummaryHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/TextWithSummaryHandlerTest.php
@@ -5,8 +5,8 @@
 namespace Drupal\Tests\Driver\Unit\Core\Field;
 
 use Drupal\Driver\Core\Field\AbstractHandler;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use Drupal\Driver\Core\Field\TextWithSummaryHandler;
-use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\Attributes\Group;
 
 /**
@@ -15,25 +15,12 @@
  * @group fields
  */
 #[Group('fields')]
-class TextWithSummaryHandlerTest extends TestCase {
+class TextWithSummaryHandlerTest extends FieldHandlerUnitTestBase {
 
   /**
-   * Tests that expand() returns a canonical list of records.
+   * {@inheritdoc}
    */
-  public function testExpandReturnsCanonicalRecordList(): void {
-    $handler = $this->createHandler();
-
-    $values = [
-      ['value' => 'body text', 'summary' => 'short'],
-    ];
-
-    $this->assertSame($values, $handler->expand($values));
-  }
-
-  /**
-   * Creates a TextWithSummaryHandler with the main property injected.
-   */
-  protected function createHandler(): TextWithSummaryHandler {
+  protected function createHandler(): FieldHandlerInterface {
     $reflection = new \ReflectionClass(TextWithSummaryHandler::class);
     $handler = $reflection->newInstanceWithoutConstructor();
 
@@ -43,4 +30,35 @@ protected function createHandler(): TextWithSummaryHandler {
     return $handler;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public static function dataProviderExpand(): \Iterator {
+    yield 'bare scalar' => [
+      'body text',
+      [['value' => 'body text']],
+      NULL,
+      NULL,
+    ];
+    yield 'single record with summary' => [
+      ['value' => 'body text', 'summary' => 'short'],
+      [['value' => 'body text', 'summary' => 'short']],
+      NULL,
+      NULL,
+    ];
+
+    yield 'mixed positional and named keys rejected' => [
+      ['body text', 'summary' => 'short'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field value cannot mix positional and named keys',
+    ];
+    yield 'record missing main property rejected' => [
+      ['summary' => 'short'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field record must include the main property "value"',
+    ];
+  }
+
 }
diff --git a/tests/Drupal/Tests/Driver/Unit/Core/Field/TimeHandlerTest.php b/tests/Drupal/Tests/Driver/Unit/Core/Field/TimeHandlerTest.php
index 4b2e4252..eaedb6a6 100644
--- a/tests/Drupal/Tests/Driver/Unit/Core/Field/TimeHandlerTest.php
+++ b/tests/Drupal/Tests/Driver/Unit/Core/Field/TimeHandlerTest.php
@@ -4,10 +4,10 @@
 
 namespace Drupal\Tests\Driver\Unit\Core\Field;
 
+use Drupal\Driver\Core\Field\AbstractHandler;
+use Drupal\Driver\Core\Field\FieldHandlerInterface;
 use Drupal\Driver\Core\Field\TimeHandler;
-use PHPUnit\Framework\TestCase;
 use PHPUnit\Framework\Attributes\Group;
-use PHPUnit\Framework\Attributes\DataProvider;
 
 /**
  * Tests the TimeHandler field handler.
@@ -15,71 +15,82 @@
  * @group fields
  */
 #[Group('fields')]
-class TimeHandlerTest extends TestCase {
+class TimeHandlerTest extends FieldHandlerUnitTestBase {
 
   /**
- * Tests time field expansion.
- *
- * @param array<int, mixed> $input
- *   The input values to expand.
- * @param array<int, mixed> $expected
- *   The expected expanded values.
- *
- * @dataProvider dataProviderExpand
- */
-  #[DataProvider('dataProviderExpand')]
-  public function testExpand(array $input, array $expected): void {
-    $handler = $this->createHandler();
-    $result = $handler->expand($input);
-    $this->assertSame($expected, $result);
+   * {@inheritdoc}
+   */
+  protected function createHandler(): FieldHandlerInterface {
+    $reflection = new \ReflectionClass(TimeHandler::class);
+    $handler = $reflection->newInstanceWithoutConstructor();
+
+    $property = new \ReflectionProperty(AbstractHandler::class, 'mainProperty');
+    $property->setValue($handler, 'value');
+
+    return $handler;
   }
 
   /**
-   * Data provider for testExpand().
+   * {@inheritdoc}
    */
   public static function dataProviderExpand(): \Iterator {
-    // Seconds past midnight for known times.
-    // 9:30 AM = 9*3600 + 30*60 = 34200.
-    // 2:15:30 PM = 14*3600 + 15*60 + 30 = 51330.
-    // Midnight = 0.
     $midnight = strtotime('today midnight');
-    yield 'numeric integer passthrough' => [
+
+    yield 'numeric integer passes through' => [
       [34200],
       [34200],
+      NULL,
+      NULL,
     ];
-    yield 'numeric string passthrough' => [
+    yield 'numeric string passes through' => [
       ['34200'],
       ['34200'],
+      NULL,
+      NULL,
     ];
-    yield 'time string 9:30 AM' => [
+    yield 'bare numeric integer' => [
+      34200,
+      [34200],
+      NULL,
+      NULL,
+    ];
+    yield 'strtotime string 9:30 AM' => [
       ['9:30 AM'],
       [strtotime('9:30 AM') - $midnight],
+      NULL,
+      NULL,
     ];
-    yield 'time string 14:15:30' => [
+    yield 'strtotime string 14:15:30' => [
       ['14:15:30'],
       [strtotime('14:15:30') - $midnight],
+      NULL,
+      NULL,
     ];
-    yield 'time string midnight' => [
+    yield 'midnight resolves to zero' => [
       ['midnight'],
       [0],
+      NULL,
+      NULL,
     ];
-    yield 'multiple mixed values' => [
+    yield 'mixed list of int and strings' => [
       [3600, '9:30 AM', '0'],
       [3600, strtotime('9:30 AM') - $midnight, '0'],
+      NULL,
+      NULL,
     ];
-  }
 
-  /**
-   * Creates a TimeHandler instance that bypasses the parent constructor.
-   *
-   * @return \Drupal\Driver\Core\Field\TimeHandler
-   *   The handler instance.
-   */
-  protected function createHandler(): TimeHandler {
-    // Use reflection to bypass AbstractHandler constructor which requires
-    // a full Drupal bootstrap.
-    $reflection = new \ReflectionClass(TimeHandler::class);
-    return $reflection->newInstanceWithoutConstructor();
+    yield 'mixed positional and named keys rejected' => [
+      [3600, 'extra' => 'unexpected'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field value cannot mix positional and named keys',
+    ];
+    yield 'record missing main property rejected' => [
+      ['unexpected' => 'oops'],
+      NULL,
+      \InvalidArgumentException::class,
+      'Field record must include the main property "value"',
+    ];
   }
 
 }
diff --git a/tests/fixtures/ConsumerProject/Driver/Field/StringLongHandler.php b/tests/fixtures/ConsumerProject/Driver/Field/StringLongHandler.php
index 264dcd96..1ee5baa5 100644
--- a/tests/fixtures/ConsumerProject/Driver/Field/StringLongHandler.php
+++ b/tests/fixtures/ConsumerProject/Driver/Field/StringLongHandler.php
@@ -25,13 +25,12 @@ class StringLongHandler extends AbstractHandler {
   /**
    * {@inheritdoc}
    */
-  public function expand($values): array {
+  protected function doExpand(array $records): array {
     $emitted = [];
 
-    foreach ((array) $values as $delta) {
-      $delta = is_array($delta) ? $delta : ['value' => $delta];
-      $delta['value'] = self::MARKER;
-      $emitted[] = $delta;
+    foreach ($records as $record) {
+      $record['value'] = self::MARKER;
+      $emitted[] = $record;
     }
 
     return $emitted;
diff --git a/tests/fixtures/ConsumerProject/Driver/Field/TextLongHandler.php b/tests/fixtures/ConsumerProject/Driver/Field/TextLongHandler.php
index 7436755a..ec482bef 100644
--- a/tests/fixtures/ConsumerProject/Driver/Field/TextLongHandler.php
+++ b/tests/fixtures/ConsumerProject/Driver/Field/TextLongHandler.php
@@ -25,13 +25,12 @@ class TextLongHandler extends AbstractHandler {
   /**
    * {@inheritdoc}
    */
-  public function expand($values): array {
+  protected function doExpand(array $records): array {
     $emitted = [];
 
-    foreach ((array) $values as $delta) {
-      $delta = is_array($delta) ? $delta : ['value' => $delta];
-      $delta['value'] = self::MARKER;
-      $emitted[] = $delta;
+    foreach ($records as $record) {
+      $record['value'] = self::MARKER;
+      $emitted[] = $record;
     }
 
     return $emitted;
diff --git a/tests/fixtures/files/fixture.bin b/tests/fixtures/files/fixture.bin
new file mode 100644
index 00000000..ee8c1ee4
--- /dev/null
+++ b/tests/fixtures/files/fixture.bin
@@ -0,0 +1 @@
+fixture