From ae328b975abcf34f7679c322cf5c8d84a6b3ae27 Mon Sep 17 00:00:00 2001
From: Neluxx <fabian.arndt96@proton.me>
Date: Wed, 26 Aug 2026 11:28:13 +0200
Subject: [PATCH 01/15] Check only own validation rule

---
 src/Traits/DataValidationTestTrait.php | 252 +++++++++++++++++--------
 1 file changed, 175 insertions(+), 77 deletions(-)

diff --git a/src/Traits/DataValidationTestTrait.php b/src/Traits/DataValidationTestTrait.php
index 8f128c2..a70d066 100644
--- a/src/Traits/DataValidationTestTrait.php
+++ b/src/Traits/DataValidationTestTrait.php
@@ -40,7 +40,7 @@ protected function testDataValidationNotEmpty(
         $list = [null, ''];
 
         $expected = ['_empty' => 'This field cannot be left empty'];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $this->testDataValidationInListContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
     }
 
     /**
@@ -67,8 +67,8 @@ protected function testDataValidationEmpty(
     ): void {
         $list = [null, ''];
 
-        $expected = [];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $expected = ['_empty'];
+        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
     }
 
     /**
@@ -88,7 +88,7 @@ protected function testDataValidationRequired(
         array $options = [],
     ): void {
         $expected = ['_required' => 'This field is required'];
-        $this->testDataValidation($table, $fieldName, $dataSet, $expected, $options);
+        $this->testDataValidationContains($table, $fieldName, $dataSet, $expected, $options);
     }
 
     /**
@@ -107,7 +107,8 @@ protected function testDataValidationNotRequired(
         array $dataSet = [],
         array $options = [],
     ): void {
-        $this->testDataValidationNoErrors($table, $fieldName, $dataSet, $options);
+        $expected = ['_required'];
+        $this->testDataValidationNotContains($table, $fieldName, $dataSet, $expected, $options);
     }
 
     /**
@@ -128,13 +129,13 @@ protected function testDataValidationBoolean(
     ): void {
         // Valid values
         $list = [true, false, 1, 0];
-        $expected = [];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $expected = ['boolean'];
+        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
 
         // Invalid values
         $list = ['Not a boolean', 123, []];
         $expected = ['boolean' => 'The provided value must be a boolean'];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $this->testDataValidationInListContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
     }
 
     /**
@@ -155,13 +156,13 @@ protected function testDataValidationURLWithProtocol(
     ): void {
         // Valid values
         $list = ['https://valid.com', 'http://valid.com'];
-        $expected = [];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $expected = ['urlWithProtocol'];
+        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
 
         // Invalid values
         $list = ['no-protocol.com', 'htp://foo.com'];
         $expected = ['urlWithProtocol' => 'The provided value must be a URL with protocol'];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $this->testDataValidationInListContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
     }
 
     /**
@@ -188,8 +189,8 @@ protected function testDataValidationDateTime(
             new Chronos(),
             new FrozenTime(),
         ];
-        $expected = [];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $expected = ['dateTime'];
+        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
 
         // Invalid values
         $list = [
@@ -200,7 +201,7 @@ protected function testDataValidationDateTime(
             '123', // Numeric
         ];
         $expected = ['dateTime' => 'The provided value must be a date and time of one of these formats: `ymd`'];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $this->testDataValidationInListContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
     }
 
     /**
@@ -229,8 +230,8 @@ protected function testDataValidationDate(
             new FrozenDate(),
             new FrozenTime(),
         ];
-        $expected = [];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $expected = ['date'];
+        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
 
         // Invalid values
         $list = [
@@ -241,7 +242,7 @@ protected function testDataValidationDate(
         $expected = [
             'date' => 'The provided value must be a date of one of these formats: `ymd`',
         ];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $this->testDataValidationInListContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
     }
 
     /**
@@ -351,6 +352,53 @@ protected function testDataValidationContains(
         $entity = $table->newEntity($dataSet, $options);
         $errors = $entity->getError($fieldName);
 
+        $this->assertDataValidationErrorsContain($fieldName, $errors, $expected);
+    }
+
+    /**
+     * Validate that a field's data validation error array does NOT contain the given rule(s)
+     *
+     * Other validation errors will be ignored.
+     *
+     * @param Table $table The table to test.
+     * @param string $fieldName The field to check for data validation errors.
+     * @param array $dataSet The data set to test.
+     * @param array $rules The rule names ("rule name") that must NOT be present.
+     * @param array $options Additional options for newEntity.
+     * @return void
+     * @see \Cake\Validation\Validator::validate()
+     */
+    protected function testDataValidationNotContains(
+        Table $table,
+        string $fieldName,
+        array $dataSet,
+        array $rules,
+        array $options = [],
+    ): void {
+        $entity = $table->newEntity($dataSet, $options);
+        $errors = $entity->getError($fieldName);
+
+        foreach ($rules as $rule) {
+            static::assertArrayNotHasKey($rule, $errors, sprintf(
+                'Field `%s` has unexpected validation error `%s`.',
+                $fieldName,
+                $rule,
+            ));
+        }
+    }
+
+    /**
+     * Assert that a given field errors array contains the expected "rule name" => "message" pair(s)
+     *
+     * Other validation errors are ignored.
+     *
+     * @param string $fieldName The field the errors belong to (used for assertion messages).
+     * @param array $errors The field's validation errors.
+     * @param array $expected The expected errors ("rule name" => "message") that must be present.
+     * @return void
+     */
+    protected function assertDataValidationErrorsContain(string $fieldName, array $errors, array $expected): void
+    {
         foreach ($expected as $rule => $message) {
             static::assertArrayHasKey($rule, $errors, sprintf(
                 'Field `%s` does not have expected validation error `%s`.',
@@ -365,6 +413,60 @@ protected function testDataValidationContains(
         }
     }
 
+    /**
+     * Validate that each value of a list of values leads to a field error containing the expected rule(s)
+     *
+     * Other validation errors will be ignored.
+     *
+     * @param Table $table The table to test.
+     * @param array $list A list of values to test.
+     * @param string $fieldName The field to check for data validation errors.
+     * @param array $expected The expected errors ("rule name" => "message") that must be present.
+     * @param array $additionalDataSet Additional data set to test.
+     * @param array $options Additional options for newEntity.
+     * @return void
+     */
+    protected function testDataValidationInListContains(
+        Table $table,
+        array $list,
+        string $fieldName,
+        array $expected = [],
+        array $additionalDataSet = [],
+        array $options = [],
+    ): void {
+        foreach ($list as $value) {
+            $dataSet = array_merge($additionalDataSet, [$fieldName => $value]);
+            $this->testDataValidationContains($table, $fieldName, $dataSet, $expected, $options);
+        }
+    }
+
+    /**
+     * Validate that each value of a list of values does NOT lead to a field error for the given rule(s)
+     *
+     * Other validation errors will be ignored.
+     *
+     * @param Table $table The table to test.
+     * @param array $list A list of values to test.
+     * @param string $fieldName The field to check for data validation errors.
+     * @param array $rules The rule names ("rule name") that must NOT be present.
+     * @param array $additionalDataSet Additional data set to test.
+     * @param array $options Additional options for newEntity.
+     * @return void
+     */
+    protected function testDataValidationInListNotContains(
+        Table $table,
+        array $list,
+        string $fieldName,
+        array $rules = [],
+        array $additionalDataSet = [],
+        array $options = [],
+    ): void {
+        foreach ($list as $value) {
+            $dataSet = array_merge($additionalDataSet, [$fieldName => $value]);
+            $this->testDataValidationNotContains($table, $fieldName, $dataSet, $rules, $options);
+        }
+    }
+
     /**
      * Validate that a given data set for a given table leads to the expected rule errors
      *
@@ -464,10 +566,8 @@ protected function testDataValidationMaxLength(
         $tooLongFieldContent = str_repeat('A', $maxLength + 1);
         $dataset = [$fieldName => $tooLongFieldContent];
 
-        $expected ??= [
-            'maxLength' => sprintf('The provided value must be at most `%d` characters long', $maxLength),
-        ];
-        $this->testDataValidation($table, $fieldName, $dataset, $expected, $options);
+        $expected ??= ['maxLength' => sprintf('The provided value must be at most `%d` characters long', $maxLength)];
+        $this->testDataValidationContains($table, $fieldName, $dataset, $expected, $options);
     }
 
     /**
@@ -490,10 +590,8 @@ protected function testDataValidationMinLength(
     ): void {
         $tooShortFieldContent = str_repeat('A', $minLength - 1);
         $dataset = [$fieldName => $tooShortFieldContent];
-        $expected ??= [
-            'minLength' => sprintf('The provided value must be at least `%d` characters long', $minLength),
-        ];
-        $this->testDataValidation($table, $fieldName, $dataset, $expected, $options);
+        $expected ??= ['minLength' => sprintf('The provided value must be at least `%d` characters long', $minLength)];
+        $this->testDataValidationContains($table, $fieldName, $dataset, $expected, $options);
     }
 
     /**
@@ -548,12 +646,12 @@ protected function testDataValidationDecimal(
         $expected ??= [
             'decimal' => 'The provided value must be decimal with any number of decimal places, including none',
         ];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, [], $options);
+        $this->testDataValidationInListContains($table, $list, $fieldName, $expected, [], $options);
 
         // Valid values
         $list = [-99.0, 0.099];
-        $expected = [];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, [], $options);
+        $expected = ['decimal'];
+        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, [], $options);
     }
 
     /**
@@ -584,12 +682,12 @@ protected function testDataValidationInteger(
             'ab0,099',
         ];
         $expected ??= ['integer' => 'The provided value must be an integer'];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, [], $options);
+        $this->testDataValidationInListContains($table, $list, $fieldName, $expected, [], $options);
 
         // Valid values
         $list = [-99, 99];
-        $expected = [];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, [], $options);
+        $expected = ['integer'];
+        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, [], $options);
     }
 
     /**
@@ -610,16 +708,15 @@ protected function testDataValidationNonNegativeInteger(
     ): void {
         // Negative integer
         $dataset = [$fieldName => '-1'];
-        $expected ??= [
-            'nonNegativeInteger' => 'The provided value must be a non-negative integer',
-        ];
+        $expected ??= ['nonNegativeInteger' => 'The provided value must be a non-negative integer'];
 
-        $this->testDataValidation($table, $fieldName, $dataset, $expected, $options);
+        $this->testDataValidationContains($table, $fieldName, $dataset, $expected, $options);
 
         // Non-negative integer
         $dataset = [$fieldName => '0'];
 
-        $this->testDataValidationNoErrors($table, $fieldName, $dataset, $options);
+        $expected = ['nonNegativeInteger'];
+        $this->testDataValidationNotContains($table, $fieldName, $dataset, $expected, $options);
     }
 
     /**
@@ -654,12 +751,13 @@ protected function testDataValidationGreaterThanOrEqual(
                 $threshold,
             ),
         ];
-        $this->testDataValidation($table, $fieldName, $dataset, $expected, $options);
+        $this->testDataValidationContains($table, $fieldName, $dataset, $expected, $options);
 
         // Valid values: exactly at and just above the threshold
         $aboveThreshold = is_int($threshold) ? $threshold + 1 : $threshold + 0.01;
         $list = [$threshold, $aboveThreshold];
-        $this->testDataValidationInList($table, $list, $fieldName, [], $additionalDataSet, $options);
+        $expected = ['greaterThanOrEqual'];
+        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
     }
 
     /**
@@ -678,15 +776,6 @@ protected function testDataValidationEmail(
         ?array $expected = null,
         ?array $options = [],
     ): void {
-        // Valid values
-        $list = [
-            'valid@email.test',
-            'VALID@EMAIL.TEST',
-            'va_lid.123@email.test',
-            'va_lid.123+spamfolder@email.test',
-        ];
-        $this->testDataValidationInList($table, $list, $fieldName, [], [], $options);
-
         // Invalid values
         $list = [
             'invalid',
@@ -694,10 +783,18 @@ protected function testDataValidationEmail(
             'in.valid',
             'in@valid.1',
         ];
-        $expected ??= [
-            'email' => 'The provided value must be an e-mail address',
+        $expected ??= ['email' => 'The provided value must be an e-mail address'];
+        $this->testDataValidationInListContains($table, $list, $fieldName, $expected, [], $options);
+
+        // Valid values
+        $list = [
+            'valid@email.test',
+            'VALID@EMAIL.TEST',
+            'va_lid.123@email.test',
+            'va_lid.123+spamfolder@email.test',
         ];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, [], $options);
+        $expected = ['email'];
+        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, [], $options);
     }
 
     /**
@@ -716,6 +813,16 @@ protected function testDataValidationUuid(
         ?array $expected = null,
         ?array $options = [],
     ): void {
+        // Invalid values
+        $list = [
+            'c232ay00-9414-11ec-b3c8-9f6bdeced846', // Invalid Hexadecimal value "y"
+            'c232aa00-941-11ec4-b3c-89f6bdeced846', // Correct length wrong format
+            '5df41881-3aed-3515-88a7-2f4a814cf09', // Too short
+            'notAUuid', // Not a UUID
+        ];
+        $expected ??= ['uuid' => 'The provided value must be a UUID'];
+        $this->testDataValidationInListContains($table, $list, $fieldName, $expected, [], $options);
+
         // Valid values
         $list = [
             'e22e1622-5c14-11ea-b2f3-0242ac130003', // UUID v1
@@ -728,19 +835,8 @@ protected function testDataValidationUuid(
             '00112233-4455-8677-8899-aabbccddeeff', // UUID v8
             'fc93ab0e-c99e-4b58-975e-9c5e68c53624', // GUID
         ];
-        $this->testDataValidationInList($table, $list, $fieldName, [], [], $options);
-
-        // Invalid values
-        $list = [
-            'c232ay00-9414-11ec-b3c8-9f6bdeced846', // Invalid Hexadecimal value "y"
-            'c232aa00-941-11ec4-b3c-89f6bdeced846', // Correct length wrong format
-            '5df41881-3aed-3515-88a7-2f4a814cf09', // Too short
-            'notAUuid', // Not a UUID
-        ];
-        $expected ??= [
-            'uuid' => 'The provided value must be a UUID',
-        ];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, [], $options);
+        $expected = ['uuid'];
+        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, [], $options);
     }
 
     /**
@@ -775,7 +871,7 @@ protected function testDataValidationLengthBetween(
                     $maxlength,
                 ),
             ];
-            $this->testDataValidation($table, $fieldName, $dataset, $expected, $options);
+            $this->testDataValidationContains($table, $fieldName, $dataset, $expected, $options);
         }
 
         // Too long
@@ -789,7 +885,7 @@ protected function testDataValidationLengthBetween(
                 $maxlength,
             ),
         ];
-        $this->testDataValidation($table, $fieldName, $dataset, $expected, $options);
+        $this->testDataValidationContains($table, $fieldName, $dataset, $expected, $options);
     }
 
     /**
@@ -808,15 +904,15 @@ protected function testDataValidationNaturalNumber(
         array $additionalDataSet = [],
         array $options = [],
     ): void {
-        // Valid value
-        $list = [1];
-        $expected = [];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, $additionalDataSet, $options);
-
         // Invalid values
         $list = [0, -1];
         $expected = ['naturalNumber' => 'The provided value must be a natural number'];
-        $this->testDataValidationInList($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $this->testDataValidationInListContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+
+        // Valid value
+        $list = [1];
+        $expected = ['naturalNumber'];
+        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
     }
 
     /**
@@ -843,23 +939,24 @@ protected function testFullDataValidation(Table $table, array $dataSet, array $e
      * @param Table $table The table to test.
      * @param string $fieldName The field to check the foreign key for.
      * @param int|null $notExistingForeignKey Not existing foreign key. Defaults to 999999.
+     * @param array|null $expected The expected rule errors ("rule name" => "message") that must be present.
      * @return void
      */
     protected function testDataValidationForeignKey(
         Table $table,
         string $fieldName,
         ?int $notExistingForeignKey = 999999,
+        ?array $expected = null,
     ): void {
         $entity = $table->newEmptyEntity();
         $table->patchEntity($entity, [$fieldName => $notExistingForeignKey]);
 
         $result = $table->checkRules($entity);
         static::assertFalse($result);
-        static::assertNotNull($entity->getErrors()[$fieldName]);
 
-        $expected = ['_existsIn' => 'This value does not exist'];
+        $expected ??= ['_existsIn' => 'This value does not exist'];
 
-        static::assertSame($expected, $entity->getErrors()[$fieldName]);
+        $this->assertDataValidationErrorsContain($fieldName, $entity->getError($fieldName), $expected);
     }
 
     /**
@@ -869,6 +966,7 @@ protected function testDataValidationForeignKey(
      * @param string $fieldName The field to check the foreign key for.
      * @param mixed $fieldValue The field value.
      * @param array $additionalProperties Other required properties for the new entity.
+     * @param array|null $expected The expected rule errors ("rule name" => "message") that must be present.
      * @return void
      */
     protected function testDataValidationIsUnique(
@@ -876,6 +974,7 @@ protected function testDataValidationIsUnique(
         string $fieldName,
         mixed $fieldValue,
         array $additionalProperties = [],
+        ?array $expected = null,
     ): void {
         $prevEntity = $table->newEmptyEntity();
         $table->patchEntity($prevEntity, array_merge($additionalProperties, [$fieldName => $fieldValue]));
@@ -886,10 +985,9 @@ protected function testDataValidationIsUnique(
 
         $result = $table->checkRules($entity);
         static::assertFalse($result);
-        static::assertNotNull($entity->getErrors()[$fieldName]);
 
-        $expected = ['_isUnique' => 'This value is already in use'];
+        $expected ??= ['_isUnique' => 'This value is already in use'];
 
-        static::assertSame($expected, $entity->getErrors()[$fieldName]);
+        $this->assertDataValidationErrorsContain($fieldName, $entity->getError($fieldName), $expected);
     }
 }

From e4fcb67120f58cf39f6a915c25a58d0d5d3be99c Mon Sep 17 00:00:00 2001
From: Neluxx <fabian.arndt96@proton.me>
Date: Wed, 26 Aug 2026 11:28:41 +0200
Subject: [PATCH 02/15] Add unit tests for new data validation helper methods

---
 .../Traits/DataValidationTestTraitTest.php    | 103 +++++++++++++++++-
 1 file changed, 101 insertions(+), 2 deletions(-)

diff --git a/tests/TestCase/Traits/DataValidationTestTraitTest.php b/tests/TestCase/Traits/DataValidationTestTraitTest.php
index e415bef..e069450 100644
--- a/tests/TestCase/Traits/DataValidationTestTraitTest.php
+++ b/tests/TestCase/Traits/DataValidationTestTraitTest.php
@@ -275,6 +275,7 @@ public function testTestDataValidationMinLength(): void
      *
      * @return void
      * @covers ::testDataValidationScalar
+     * @covers ::testDataValidationContains
      */
     public function testTestDataValidationScalar(): void
     {
@@ -509,13 +510,13 @@ public function testTestDataRulesNoErrors(): void
     {
         // Ensure the rule works as expected first
         $field = 'unique_field';
-        $dataSet = [$field => 'unique-value-' . uniqid()];
+        $dataSet = [$field => 'unique-value-' . uniqid('', true)];
 
         $entity = $this->table->newEntity($dataSet, ['validate' => false]);
         static::assertNotFalse($this->table->save($entity));
         static::assertEmpty($entity->getError($field));
 
-        $this->testDataRulesNoErrors($this->table, $field, [$field => 'another-unique-' . uniqid()]);
+        $this->testDataRulesNoErrors($this->table, $field, [$field => 'another-unique-' . uniqid('', true)]);
     }
 
     /**
@@ -603,4 +604,102 @@ public function testTestRules(): void
 
         $this->testRules($this->table, $field, $dataSet, $expectedErrors);
     }
+
+    /**
+     * Test the testDataValidationNotContains base method.
+     *
+     * @return void
+     * @covers ::testDataValidationNotContains
+     */
+    public function testTestDataValidationNotContains(): void
+    {
+        // A valid boolean value must not produce a `boolean` error
+        $field = 'boolean_field';
+        $entity = $this->table->newEntity([$field => true]);
+        static::assertArrayNotHasKey('boolean', $entity->getError($field));
+
+        $this->testDataValidationNotContains($this->table, $field, [$field => true], ['boolean']);
+    }
+
+    /**
+     * Test the testDataValidationInListContains base method.
+     *
+     * @return void
+     * @covers ::testDataValidationInListContains
+     * @covers ::assertDataValidationErrorsContain
+     */
+    public function testTestDataValidationInListContains(): void
+    {
+        $field = 'boolean_field';
+        $expectedErrors = ['boolean' => 'The provided value must be a boolean'];
+        $invalidValues = ['Not a boolean', 123];
+
+        $this->testDataValidationInListContains($this->table, $invalidValues, $field, $expectedErrors);
+    }
+
+    /**
+     * Test the testDataValidationInListNotContains base method.
+     *
+     * @return void
+     * @covers ::testDataValidationInListNotContains
+     */
+    public function testTestDataValidationInListNotContains(): void
+    {
+        $field = 'boolean_field';
+        $validValues = [true, false, 1, 0];
+
+        $this->testDataValidationInListNotContains($this->table, $validValues, $field, ['boolean']);
+    }
+
+    /**
+     * Test that a type-specific method only asserts its own rule and ignores unrelated errors.
+     *
+     * @return void
+     * @covers ::testDataValidationInteger
+     */
+    public function testTypeSpecificMethodIgnoresUnrelatedErrors(): void
+    {
+        $field = 'multi_rule_field';
+
+        // The invalid value triggers both the integer and the (unrelated) maxLength rule
+        $entity = $this->table->newEntity([$field => 'abcd']);
+        $errors = $entity->getError($field);
+        static::assertArrayHasKey('integer', $errors);
+        static::assertArrayHasKey('maxLength', $errors);
+
+        // The type-specific method still passes because it only checks its own `integer` rule
+        $this->testDataValidationInteger($this->table, $field);
+    }
+
+    /**
+     * Test that testDataValidationForeignKey accepts a custom expected error.
+     *
+     * @return void
+     * @covers ::testDataValidationForeignKey
+     */
+    public function testTestDataValidationForeignKeyCustomExpected(): void
+    {
+        $field = 'parent_id';
+        $expectedErrors = ['_existsIn' => 'This value does not exist'];
+
+        $this->testDataValidationForeignKey($this->table, $field, 999999, $expectedErrors);
+    }
+
+    /**
+     * Test that testDataValidationIsUnique accepts a custom expected error.
+     *
+     * @return void
+     * @covers ::testDataValidationIsUnique
+     */
+    public function testTestDataValidationIsUniqueCustomExpected(): void
+    {
+        $field = 'unique_field';
+        $dataset = [
+            $field => 'custom-duplicate-value',
+            'required_field' => 'required',
+        ];
+        $expectedErrors = ['_isUnique' => 'This value is already in use'];
+
+        $this->testDataValidationIsUnique($this->table, $field, 'custom-duplicate-value', $dataset, $expectedErrors);
+    }
 }

From 9ae88fc4cc71bc5b209e9ebbd46c554462d8b254 Mon Sep 17 00:00:00 2001
From: Neluxx <fabian.arndt96@proton.me>
Date: Wed, 26 Aug 2026 11:29:43 +0200
Subject: [PATCH 03/15] Add multi_rule_field to validation_test table

---
 tests/TestApp/Model/Table/ValidationTestTable.php | 7 ++++++-
 tests/bootstrap.php                               | 3 ++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/tests/TestApp/Model/Table/ValidationTestTable.php b/tests/TestApp/Model/Table/ValidationTestTable.php
index 49e18dd..ae345d5 100644
--- a/tests/TestApp/Model/Table/ValidationTestTable.php
+++ b/tests/TestApp/Model/Table/ValidationTestTable.php
@@ -65,7 +65,12 @@ public function validationDefault(Validator $validator): Validator
             ->allowEmptyString('parent_id')
             ->integer('parent_id')
             ->email('email_field')
-            ->uuid('uuid_field');
+            ->uuid('uuid_field')
+            // A field with more than one validation rule, used to assert that the
+            // type-specific trait methods only check their own rule and ignore others.
+            ->integer('multi_rule_field')
+            ->maxLength('multi_rule_field', 3)
+            ->allowEmptyString('multi_rule_field');
 
         return $validator;
     }
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 8dfa39f..180a94a 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -82,7 +82,8 @@
         natural_number_field INTEGER,
         unique_field VARCHAR(255) UNIQUE,
         email_field VARCHAR(255),
-        uuid VARCHAR(36)
+        uuid VARCHAR(36),
+        multi_rule_field VARCHAR(255)
     )
 ');
 

From 2cd35491855253041ad346e26275d1b0dfcb2f94 Mon Sep 17 00:00:00 2001
From: Neluxx <fabian.arndt96@proton.me>
Date: Wed, 26 Aug 2026 11:37:37 +0200
Subject: [PATCH 04/15] Update usage guide

---
 docs/Usage.md | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/docs/Usage.md b/docs/Usage.md
index 3558e43..936cdd1 100644
--- a/docs/Usage.md
+++ b/docs/Usage.md
@@ -83,9 +83,13 @@ Each helper builds an entity, runs the validator, and asserts the expected error
 
 ### Generic helpers
 
-- `testDataValidation($table, $fieldName, $dataSet, $expected)` - the underlying helper. Use when no specialized helper fits.
+- `testDataValidation($table, $fieldName, $dataSet, $expected)` - the underlying helper. Use when no specialized helper fits. Compares the field's **complete** error array against `$expected`.
+- `testDataValidationContains($table, $fieldName, $dataSet, $expected)` - asserts the given `"rule name" => "message"` pairs are present on the field, ignoring any other errors.
+- `testDataValidationNotContains($table, $fieldName, $dataSet, $rules)` - asserts the given rule names are **not** present on the field, ignoring any other errors.
 - `testDataValidationNoErrors($table, $fieldName, $dataSet)` - asserts a data set produces no errors on the field.
-- `testDataValidationInList($table, $list, $fieldName, $expected)` - runs the same assertion for each value in a list.
+- `testDataValidationInList($table, $list, $fieldName, $expected)` - runs the complete-error-array assertion for each value in a list.
+- `testDataValidationInListContains($table, $list, $fieldName, $expected)` - runs the `contains` assertion for each value in a list.
+- `testDataValidationInListNotContains($table, $list, $fieldName, $rules)` - runs the `not contains` assertion for each value in a list.
 - `testFullDataValidation($table, $dataSet, $expected)` - asserts errors across all fields.
 - `testFullDataValidationNoErrors($table, $dataSet)` - asserts a full data set produces no errors at all.
 

From b5d9280c7b8554a142e5ec1f1b40f8060439ff51 Mon Sep 17 00:00:00 2001
From: Neluxx <fabian.arndt96@proton.me>
Date: Wed, 26 Aug 2026 11:38:48 +0200
Subject: [PATCH 05/15] Update change log

---
 CHANGELOG.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7c23ea4..b2429fd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,8 +6,12 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ## [Unreleased](https://github.com/orca-services/cakephp-data-validation-testing)
 
 ### Added
+- `testDataValidationNotContains()` to assert that specific validation rules are absent, ignoring others on the same field.
+- `testDataValidationInListContains()` and `testDataValidationInListNotContains()` list helpers.
+- Optional custom `$expected` parameter for `testDataValidationForeignKey()` and `testDataValidationIsUnique()`.
 
 ### Changed
+- **BREAKING CHANGE:** All type-specific/rule-dedicated methods now assert only their own validation rule for the field.
 
 ### Fixed
 

From 61af2691461be36c4ac4a9a095aefbdb56d47d05 Mon Sep 17 00:00:00 2001
From: "maurin.stutz" <maurin.stutz@orca.ch>
Date: Wed, 26 Aug 2026 15:10:24 +0200
Subject: [PATCH 06/15] Improve parameter documentation

---
 src/Traits/DataValidationTestTrait.php | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Traits/DataValidationTestTrait.php b/src/Traits/DataValidationTestTrait.php
index a70d066..da0f6df 100644
--- a/src/Traits/DataValidationTestTrait.php
+++ b/src/Traits/DataValidationTestTrait.php
@@ -960,11 +960,11 @@ protected function testDataValidationForeignKey(
     }
 
     /**
-     * Validate the uniq value of the given field
+     * Validate the unique value of the given field
      *
      * @param Table $table The table to test.
      * @param string $fieldName The field to check the foreign key for.
-     * @param mixed $fieldValue The field value.
+     * @param mixed $fieldValue The field value which will be saved twice (must be unique).
      * @param array $additionalProperties Other required properties for the new entity.
      * @param array|null $expected The expected rule errors ("rule name" => "message") that must be present.
      * @return void

From 48634c84eb76aef22516eb9188c2cc1c8b6e9748 Mon Sep 17 00:00:00 2001
From: "maurin.stutz" <maurin.stutz@orca.ch>
Date: Thu, 27 Aug 2026 08:39:14 +0200
Subject: [PATCH 07/15] Ignore dataValidation in `testDataValidationIsUnique()`
 to correctly assert build rules.

---
 CHANGELOG.md                           |  1 +
 src/Traits/DataValidationTestTrait.php | 12 ++++++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index b2429fd..fca358d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - **BREAKING CHANGE:** All type-specific/rule-dedicated methods now assert only their own validation rule for the field.
 
 ### Fixed
+- Ignore dataValidation in `testDataValidationIsUnique()` to correctly assert build rules.
 
 ### Dependencies
 
diff --git a/src/Traits/DataValidationTestTrait.php b/src/Traits/DataValidationTestTrait.php
index da0f6df..577eaeb 100644
--- a/src/Traits/DataValidationTestTrait.php
+++ b/src/Traits/DataValidationTestTrait.php
@@ -977,11 +977,19 @@ protected function testDataValidationIsUnique(
         ?array $expected = null,
     ): void {
         $prevEntity = $table->newEmptyEntity();
-        $table->patchEntity($prevEntity, array_merge($additionalProperties, [$fieldName => $fieldValue]));
+        $table->patchEntity(
+            $prevEntity,
+            array_merge($additionalProperties, [$fieldName => $fieldValue]),
+            ['validate' => false],
+        );
         $table->saveOrFail($prevEntity);
 
         $entity = $table->newEmptyEntity();
-        $table->patchEntity($entity, array_merge($additionalProperties, [$fieldName => $fieldValue]));
+        $table->patchEntity(
+            $entity,
+            array_merge($additionalProperties, [$fieldName => $fieldValue]),
+            ['validate' => false],
+        );
 
         $result = $table->checkRules($entity);
         static::assertFalse($result);

From f384526d2316982486d9de629bd5024f7c7c7790 Mon Sep 17 00:00:00 2001
From: Fabian Arndt <fabian.arndt96@proton.me>
Date: Thu, 27 Aug 2026 13:35:34 +0200
Subject: [PATCH 08/15] Apply suggestions from code review
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Marc Würth <ravage@bluewin.ch>
---
 CHANGELOG.md                                          | 2 +-
 tests/TestApp/Model/Table/ValidationTestTable.php     | 1 +
 tests/TestCase/Traits/DataValidationTestTraitTest.php | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index fca358d..efd78e2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,7 +11,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - Optional custom `$expected` parameter for `testDataValidationForeignKey()` and `testDataValidationIsUnique()`.
 
 ### Changed
-- **BREAKING CHANGE:** All type-specific/rule-dedicated methods now assert only their own validation rule for the field.
+- **BREAKING CHANGE:** All type-specific/rule-dedicated methods now assert only their own validation rule for the field, ignoring others.
 
 ### Fixed
 - Ignore dataValidation in `testDataValidationIsUnique()` to correctly assert build rules.
diff --git a/tests/TestApp/Model/Table/ValidationTestTable.php b/tests/TestApp/Model/Table/ValidationTestTable.php
index ae345d5..4f6455f 100644
--- a/tests/TestApp/Model/Table/ValidationTestTable.php
+++ b/tests/TestApp/Model/Table/ValidationTestTable.php
@@ -68,6 +68,7 @@ public function validationDefault(Validator $validator): Validator
             ->uuid('uuid_field')
             // A field with more than one validation rule, used to assert that the
             // type-specific trait methods only check their own rule and ignore others.
+            ->requirePresence('multi_rule_field')
             ->integer('multi_rule_field')
             ->maxLength('multi_rule_field', 3)
             ->allowEmptyString('multi_rule_field');
diff --git a/tests/TestCase/Traits/DataValidationTestTraitTest.php b/tests/TestCase/Traits/DataValidationTestTraitTest.php
index e069450..f62ebe8 100644
--- a/tests/TestCase/Traits/DataValidationTestTraitTest.php
+++ b/tests/TestCase/Traits/DataValidationTestTraitTest.php
@@ -667,7 +667,7 @@ public function testTypeSpecificMethodIgnoresUnrelatedErrors(): void
         static::assertArrayHasKey('integer', $errors);
         static::assertArrayHasKey('maxLength', $errors);
 
-        // The type-specific method still passes because it only checks its own `integer` rule
+        // The type-specific method still passes because it checks for the `integer` rule, only
         $this->testDataValidationInteger($this->table, $field);
     }
 

From 1ef92414982cae29ab4a6d5512919f4bac63b01e Mon Sep 17 00:00:00 2001
From: Neluxx <fabian.arndt96@proton.me>
Date: Thu, 27 Aug 2026 14:43:45 +0200
Subject: [PATCH 09/15] Rename $expected to $notExpected in rule-dedicated
 methods

---
 src/Traits/DataValidationTestTrait.php | 101 ++++++++++++++++++-------
 1 file changed, 75 insertions(+), 26 deletions(-)

diff --git a/src/Traits/DataValidationTestTrait.php b/src/Traits/DataValidationTestTrait.php
index 577eaeb..93f5c39 100644
--- a/src/Traits/DataValidationTestTrait.php
+++ b/src/Traits/DataValidationTestTrait.php
@@ -67,8 +67,15 @@ protected function testDataValidationEmpty(
     ): void {
         $list = [null, ''];
 
-        $expected = ['_empty'];
-        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $notExpected = ['_empty'];
+        $this->testDataValidationInListNotContains(
+            $table,
+            $list,
+            $fieldName,
+            $notExpected,
+            $additionalDataSet,
+            $options,
+        );
     }
 
     /**
@@ -107,8 +114,8 @@ protected function testDataValidationNotRequired(
         array $dataSet = [],
         array $options = [],
     ): void {
-        $expected = ['_required'];
-        $this->testDataValidationNotContains($table, $fieldName, $dataSet, $expected, $options);
+        $notExpected = ['_required'];
+        $this->testDataValidationNotContains($table, $fieldName, $dataSet, $notExpected, $options);
     }
 
     /**
@@ -129,8 +136,15 @@ protected function testDataValidationBoolean(
     ): void {
         // Valid values
         $list = [true, false, 1, 0];
-        $expected = ['boolean'];
-        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $notExpected = ['boolean'];
+        $this->testDataValidationInListNotContains(
+            $table,
+            $list,
+            $fieldName,
+            $notExpected,
+            $additionalDataSet,
+            $options,
+        );
 
         // Invalid values
         $list = ['Not a boolean', 123, []];
@@ -156,8 +170,15 @@ protected function testDataValidationURLWithProtocol(
     ): void {
         // Valid values
         $list = ['https://valid.com', 'http://valid.com'];
-        $expected = ['urlWithProtocol'];
-        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $notExpected = ['urlWithProtocol'];
+        $this->testDataValidationInListNotContains(
+            $table,
+            $list,
+            $fieldName,
+            $notExpected,
+            $additionalDataSet,
+            $options,
+        );
 
         // Invalid values
         $list = ['no-protocol.com', 'htp://foo.com'];
@@ -189,8 +210,15 @@ protected function testDataValidationDateTime(
             new Chronos(),
             new FrozenTime(),
         ];
-        $expected = ['dateTime'];
-        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $notExpected = ['dateTime'];
+        $this->testDataValidationInListNotContains(
+            $table,
+            $list,
+            $fieldName,
+            $notExpected,
+            $additionalDataSet,
+            $options,
+        );
 
         // Invalid values
         $list = [
@@ -230,8 +258,15 @@ protected function testDataValidationDate(
             new FrozenDate(),
             new FrozenTime(),
         ];
-        $expected = ['date'];
-        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $notExpected = ['date'];
+        $this->testDataValidationInListNotContains(
+            $table,
+            $list,
+            $fieldName,
+            $notExpected,
+            $additionalDataSet,
+            $options,
+        );
 
         // Invalid values
         $list = [
@@ -650,8 +685,8 @@ protected function testDataValidationDecimal(
 
         // Valid values
         $list = [-99.0, 0.099];
-        $expected = ['decimal'];
-        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, [], $options);
+        $notExpected = ['decimal'];
+        $this->testDataValidationInListNotContains($table, $list, $fieldName, $notExpected, [], $options);
     }
 
     /**
@@ -686,8 +721,8 @@ protected function testDataValidationInteger(
 
         // Valid values
         $list = [-99, 99];
-        $expected = ['integer'];
-        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, [], $options);
+        $notExpected = ['integer'];
+        $this->testDataValidationInListNotContains($table, $list, $fieldName, $notExpected, [], $options);
     }
 
     /**
@@ -715,8 +750,8 @@ protected function testDataValidationNonNegativeInteger(
         // Non-negative integer
         $dataset = [$fieldName => '0'];
 
-        $expected = ['nonNegativeInteger'];
-        $this->testDataValidationNotContains($table, $fieldName, $dataset, $expected, $options);
+        $notExpected = ['nonNegativeInteger'];
+        $this->testDataValidationNotContains($table, $fieldName, $dataset, $notExpected, $options);
     }
 
     /**
@@ -756,8 +791,15 @@ protected function testDataValidationGreaterThanOrEqual(
         // Valid values: exactly at and just above the threshold
         $aboveThreshold = is_int($threshold) ? $threshold + 1 : $threshold + 0.01;
         $list = [$threshold, $aboveThreshold];
-        $expected = ['greaterThanOrEqual'];
-        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $notExpected = ['greaterThanOrEqual'];
+        $this->testDataValidationInListNotContains(
+            $table,
+            $list,
+            $fieldName,
+            $notExpected,
+            $additionalDataSet,
+            $options,
+        );
     }
 
     /**
@@ -793,8 +835,8 @@ protected function testDataValidationEmail(
             'va_lid.123@email.test',
             'va_lid.123+spamfolder@email.test',
         ];
-        $expected = ['email'];
-        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, [], $options);
+        $notExpected = ['email'];
+        $this->testDataValidationInListNotContains($table, $list, $fieldName, $notExpected, [], $options);
     }
 
     /**
@@ -835,8 +877,8 @@ protected function testDataValidationUuid(
             '00112233-4455-8677-8899-aabbccddeeff', // UUID v8
             'fc93ab0e-c99e-4b58-975e-9c5e68c53624', // GUID
         ];
-        $expected = ['uuid'];
-        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, [], $options);
+        $notExpected = ['uuid'];
+        $this->testDataValidationInListNotContains($table, $list, $fieldName, $notExpected, [], $options);
     }
 
     /**
@@ -911,8 +953,15 @@ protected function testDataValidationNaturalNumber(
 
         // Valid value
         $list = [1];
-        $expected = ['naturalNumber'];
-        $this->testDataValidationInListNotContains($table, $list, $fieldName, $expected, $additionalDataSet, $options);
+        $notExpected = ['naturalNumber'];
+        $this->testDataValidationInListNotContains(
+            $table,
+            $list,
+            $fieldName,
+            $notExpected,
+            $additionalDataSet,
+            $options,
+        );
     }
 
     /**

From eda5a2879c5148891176299e5b6d5b027a3f6819 Mon Sep 17 00:00:00 2001
From: Neluxx <fabian.arndt96@proton.me>
Date: Thu, 27 Aug 2026 14:46:48 +0200
Subject: [PATCH 10/15] Reword type validator docs to describe the asserted
 rule

---
 docs/Usage.md | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

diff --git a/docs/Usage.md b/docs/Usage.md
index 936cdd1..aa86a09 100644
--- a/docs/Usage.md
+++ b/docs/Usage.md
@@ -55,25 +55,25 @@ Each helper builds an entity, runs the validator, and asserts the expected error
 
 ### Presence and emptiness
 
-- `testDataValidationRequired($table, $fieldName)` - field must be present.
-- `testDataValidationNotRequired($table, $fieldName)` - field is optional.
-- `testDataValidationNotEmpty($table, $fieldName)` - field cannot be `null` or `''`.
-- `testDataValidationEmpty($table, $fieldName)` - field may be `null` or `''`.
+- `testDataValidationRequired($table, $fieldName)` - asserts the field is configured to require presence (`_required`).
+- `testDataValidationNotRequired($table, $fieldName)` - asserts the field is not configured to require presence.
+- `testDataValidationNotEmpty($table, $fieldName)` - asserts the field is configured to disallow empty values, i.e. `null` or `''` (`_empty`).
+- `testDataValidationEmpty($table, $fieldName)` - asserts the field is configured to allow empty values, i.e. `null` or `''`.
 
 ### Type validators
 
-- `testDataValidationBoolean($table, $fieldName)` - field must be boolean.
-- `testDataValidationURLWithProtocol($table, $fieldName)` - requires `http://` or `https://`.
-- `testDataValidationDateTime($table, $fieldName)` - field must be datetime.
-- `testDataValidationDate($table, $fieldName)` - field must be date.
-- `testDataValidationNaturalNumber($table, $fieldName)` - positive integers only.
-- `testDataValidationScalar($table, $fieldName)` - rejects non-scalar values like arrays.
-- `testDataValidationDecimal($table, $fieldName)` - rejects non-decimal values like arrays.
-- `testDataValidationInteger($table, $fieldName)` - rejects non-integer values like arrays.
-- `testDataValidationNonNegativeInteger($table, $fieldName)` - rejects negative integer values like `-1`.
-- `testDataValidationGreaterThanOrEqual($table, $fieldName)` - rejects values below the threshold.
-- `testDataValidationEmail($table, $fieldName)` - rejects invalid email addresses.
-- `testDataValidationUuid($table, $fieldName)` - rejects invalid UUIDs.
+- `testDataValidationBoolean($table, $fieldName)` - asserts the field is configured with the `boolean` validation rule.
+- `testDataValidationURLWithProtocol($table, $fieldName)` - asserts the field is configured with the `urlWithProtocol` validation rule (requires `http://` or `https://`).
+- `testDataValidationDateTime($table, $fieldName)` - asserts the field is configured with the `dateTime` validation rule.
+- `testDataValidationDate($table, $fieldName)` - asserts the field is configured with the `date` validation rule.
+- `testDataValidationNaturalNumber($table, $fieldName)` - asserts the field is configured with the `naturalNumber` validation rule (positive integers).
+- `testDataValidationScalar($table, $fieldName)` - asserts the field is configured with the `scalar` validation rule.
+- `testDataValidationDecimal($table, $fieldName)` - asserts the field is configured with the `decimal` validation rule.
+- `testDataValidationInteger($table, $fieldName)` - asserts the field is configured with the `integer` validation rule.
+- `testDataValidationNonNegativeInteger($table, $fieldName)` - asserts the field is configured with the `nonNegativeInteger` validation rule.
+- `testDataValidationGreaterThanOrEqual($table, $fieldName, $threshold)` - asserts the field is configured with the `greaterThanOrEqual` validation rule.
+- `testDataValidationEmail($table, $fieldName)` - asserts the field is configured with the `email` validation rule.
+- `testDataValidationUuid($table, $fieldName)` - asserts the field is configured with the `uuid` validation rule.
 
 ### Length validators
 

From 03f2db8d133edacb137c277dd817032b7d4945af Mon Sep 17 00:00:00 2001
From: Neluxx <fabian.arndt96@proton.me>
Date: Thu, 27 Aug 2026 14:47:07 +0200
Subject: [PATCH 11/15] Note that rule-dedicated helpers assert only their own
 rule

---
 docs/Usage.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/docs/Usage.md b/docs/Usage.md
index aa86a09..d8f643a 100644
--- a/docs/Usage.md
+++ b/docs/Usage.md
@@ -53,6 +53,10 @@ Each helper builds an entity, runs the validator, and asserts the expected error
 
 ## Available methods
 
+> **Note:** The presence, emptiness and type helpers listed below are rule-dedicated: each one only asserts that
+> its own validation rule is (or is not) configured for the given field and ignores any other validation errors
+> present on that field. They no longer compare against the field's full error list.
+
 ### Presence and emptiness
 
 - `testDataValidationRequired($table, $fieldName)` - asserts the field is configured to require presence (`_required`).

From 0a9b52dfad658bb9f60b221aa1ae0e4f769a1bc1 Mon Sep 17 00:00:00 2001
From: Neluxx <fabian.arndt96@proton.me>
Date: Thu, 27 Aug 2026 14:48:27 +0200
Subject: [PATCH 12/15] Group custom expected tests next to their sibling test
 cases

---
 .../Traits/DataValidationTestTraitTest.php    | 64 +++++++++----------
 1 file changed, 32 insertions(+), 32 deletions(-)

diff --git a/tests/TestCase/Traits/DataValidationTestTraitTest.php b/tests/TestCase/Traits/DataValidationTestTraitTest.php
index f62ebe8..96e3d9f 100644
--- a/tests/TestCase/Traits/DataValidationTestTraitTest.php
+++ b/tests/TestCase/Traits/DataValidationTestTraitTest.php
@@ -551,6 +551,20 @@ public function testTestDataValidationForeignKeyDefault(): void
         $this->testDataValidationForeignKey($this->table, $field);
     }
 
+    /**
+     * Test that testDataValidationForeignKey accepts a custom expected error.
+     *
+     * @return void
+     * @covers ::testDataValidationForeignKey
+     */
+    public function testTestDataValidationForeignKeyCustomExpected(): void
+    {
+        $field = 'parent_id';
+        $expectedErrors = ['_existsIn' => 'This value does not exist'];
+
+        $this->testDataValidationForeignKey($this->table, $field, 999999, $expectedErrors);
+    }
+
     /**
      * Test that testDataValidationIsUnique passes when the field value is not unique.
      *
@@ -580,6 +594,24 @@ public function testTestDataValidationIsUnique(): void
         $this->testDataValidationIsUnique($this->table, $field, 'another-duplicate-value', $dataset);
     }
 
+    /**
+     * Test that testDataValidationIsUnique accepts a custom expected error.
+     *
+     * @return void
+     * @covers ::testDataValidationIsUnique
+     */
+    public function testTestDataValidationIsUniqueCustomExpected(): void
+    {
+        $field = 'unique_field';
+        $dataset = [
+            $field => 'custom-duplicate-value',
+            'required_field' => 'required',
+        ];
+        $expectedErrors = ['_isUnique' => 'This value is already in use'];
+
+        $this->testDataValidationIsUnique($this->table, $field, 'custom-duplicate-value', $dataset, $expectedErrors);
+    }
+
     /**
      * Test that testRules passes when saving leads to the expected rule errors.
      *
@@ -670,36 +702,4 @@ public function testTypeSpecificMethodIgnoresUnrelatedErrors(): void
         // The type-specific method still passes because it checks for the `integer` rule, only
         $this->testDataValidationInteger($this->table, $field);
     }
-
-    /**
-     * Test that testDataValidationForeignKey accepts a custom expected error.
-     *
-     * @return void
-     * @covers ::testDataValidationForeignKey
-     */
-    public function testTestDataValidationForeignKeyCustomExpected(): void
-    {
-        $field = 'parent_id';
-        $expectedErrors = ['_existsIn' => 'This value does not exist'];
-
-        $this->testDataValidationForeignKey($this->table, $field, 999999, $expectedErrors);
-    }
-
-    /**
-     * Test that testDataValidationIsUnique accepts a custom expected error.
-     *
-     * @return void
-     * @covers ::testDataValidationIsUnique
-     */
-    public function testTestDataValidationIsUniqueCustomExpected(): void
-    {
-        $field = 'unique_field';
-        $dataset = [
-            $field => 'custom-duplicate-value',
-            'required_field' => 'required',
-        ];
-        $expectedErrors = ['_isUnique' => 'This value is already in use'];
-
-        $this->testDataValidationIsUnique($this->table, $field, 'custom-duplicate-value', $dataset, $expectedErrors);
-    }
 }

From a8b30e6353b0546066bc0407836a4f44ae112cb7 Mon Sep 17 00:00:00 2001
From: Neluxx <fabian.arndt96@proton.me>
Date: Thu, 27 Aug 2026 14:49:29 +0200
Subject: [PATCH 13/15] Add dedicated test for testDataValidationContains
 helper

---
 .../Traits/DataValidationTestTraitTest.php    | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/tests/TestCase/Traits/DataValidationTestTraitTest.php b/tests/TestCase/Traits/DataValidationTestTraitTest.php
index 96e3d9f..6b8c7fd 100644
--- a/tests/TestCase/Traits/DataValidationTestTraitTest.php
+++ b/tests/TestCase/Traits/DataValidationTestTraitTest.php
@@ -275,7 +275,6 @@ public function testTestDataValidationMinLength(): void
      *
      * @return void
      * @covers ::testDataValidationScalar
-     * @covers ::testDataValidationContains
      */
     public function testTestDataValidationScalar(): void
     {
@@ -637,6 +636,24 @@ public function testTestRules(): void
         $this->testRules($this->table, $field, $dataSet, $expectedErrors);
     }
 
+    /**
+     * Test the testDataValidationContains base method.
+     *
+     * @return void
+     * @covers ::testDataValidationContains
+     */
+    public function testTestDataValidationContains(): void
+    {
+        // An invalid scalar value must produce a `scalar` error
+        $field = 'scalar_field';
+        $expectedErrors = ['scalar' => 'The provided value must be scalar'];
+        $dataSet = [$field => []];
+        $entity = $this->table->newEntity($dataSet);
+        static::assertArrayHasKey('scalar', $entity->getError($field));
+
+        $this->testDataValidationContains($this->table, $field, $dataSet, $expectedErrors);
+    }
+
     /**
      * Test the testDataValidationNotContains base method.
      *

From ef99a91be07315426db90d417b846bee4aabea40 Mon Sep 17 00:00:00 2001
From: Neluxx <fabian.arndt96@proton.me>
Date: Thu, 27 Aug 2026 14:51:18 +0200
Subject: [PATCH 14/15] Adjust unit tests

---
 tests/TestCase/Traits/DataValidationTestTraitTest.php | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/tests/TestCase/Traits/DataValidationTestTraitTest.php b/tests/TestCase/Traits/DataValidationTestTraitTest.php
index 6b8c7fd..fc30589 100644
--- a/tests/TestCase/Traits/DataValidationTestTraitTest.php
+++ b/tests/TestCase/Traits/DataValidationTestTraitTest.php
@@ -280,9 +280,8 @@ public function testTestDataValidationScalar(): void
     {
         // Ensure data validation of the field works as expected first
         $field = 'scalar_field';
-        $expectedErrors = ['scalar' => 'The provided value must be scalar'];
-        $dataSet = [$field => []];
-        $this->testDataValidationContains($this->table, $field, $dataSet, $expectedErrors);
+        $entity = $this->table->newEntity([$field => []]);
+        static::assertArrayHasKey('scalar', $entity->getError($field));
 
         $this->testDataValidationScalar($this->table, $field);
     }
@@ -456,7 +455,7 @@ public function testTestDataValidationNaturalNumber(): void
      */
     public function testTestFullDataValidationNoErrors(): void
     {
-        $dataSet = ['required_field' => 'required'];
+        $dataSet = ['required_field' => 'required', 'multi_rule_field' => 1];
         $this->testFullDataValidationNoErrors($this->table, $dataSet);
     }
 
@@ -468,7 +467,7 @@ public function testTestFullDataValidationNoErrors(): void
      */
     public function testTestFullDataValidation(): void
     {
-        $dataSet = ['not_empty_field' => ''];
+        $dataSet = ['not_empty_field' => '', 'multi_rule_field' => 1];
         $expectedErrors = [
             'not_empty_field' => ['_empty' => 'This field cannot be left empty'],
             'required_field' => ['_required' => 'This field is required'],
@@ -620,7 +619,7 @@ public function testTestDataValidationIsUniqueCustomExpected(): void
     public function testTestRules(): void
     {
         $field = 'unique_field';
-        $dataSet = ['required_field' => 'required', $field => 'duplicate'];
+        $dataSet = ['required_field' => 'required', $field => 'duplicate', 'multi_rule_field' => 1];
         $expectedErrors = ['_isUnique' => 'This value is already in use'];
 
         // Ensure a first record exists so the unique rule will fail on the second

From 182cca46464d5cb84fb60014105910e47aafcde2 Mon Sep 17 00:00:00 2001
From: Neluxx <fabian.arndt96@proton.me>
Date: Thu, 27 Aug 2026 14:55:26 +0200
Subject: [PATCH 15/15] Add dedicated test for
 assertDataValidationErrorsContain helper

---
 .../Traits/DataValidationTestTraitTest.php    | 20 ++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/tests/TestCase/Traits/DataValidationTestTraitTest.php b/tests/TestCase/Traits/DataValidationTestTraitTest.php
index fc30589..8643a39 100644
--- a/tests/TestCase/Traits/DataValidationTestTraitTest.php
+++ b/tests/TestCase/Traits/DataValidationTestTraitTest.php
@@ -674,7 +674,6 @@ public function testTestDataValidationNotContains(): void
      *
      * @return void
      * @covers ::testDataValidationInListContains
-     * @covers ::assertDataValidationErrorsContain
      */
     public function testTestDataValidationInListContains(): void
     {
@@ -699,6 +698,25 @@ public function testTestDataValidationInListNotContains(): void
         $this->testDataValidationInListNotContains($this->table, $validValues, $field, ['boolean']);
     }
 
+    /**
+     * Test the assertDataValidationErrorsContain base method.
+     *
+     * @return void
+     * @covers ::assertDataValidationErrorsContain
+     */
+    public function testAssertDataValidationErrorsContain(): void
+    {
+        $field = 'boolean_field';
+        // The errors contain the expected rule alongside an unrelated one, which must be ignored
+        $errors = [
+            'boolean' => 'The provided value must be a boolean',
+            'maxLength' => 'The provided value is too long',
+        ];
+        $expected = ['boolean' => 'The provided value must be a boolean'];
+
+        $this->assertDataValidationErrorsContain($field, $errors, $expected);
+    }
+
     /**
      * Test that a type-specific method only asserts its own rule and ignores unrelated errors.
      *