test: ensure "table not found" raises ValueError properly

Author: DeflateAwning

src/polars_access_mdbtools/__init__.py

@@ -125,17 +125,31 @@ def _read_table_mdb_schema(
         table_name,
         str(db_path),
     ]
-    cmd_output = subprocess.check_output(cmd)  # noqa: S603
+    try:
+        cmd_output = subprocess.check_output(cmd, stderr=subprocess.STDOUT)  # noqa: S603
+    except subprocess.CalledProcessError as e:
+        # Remap "table not found" problem.
+        if b"No table named" in e.output:
+            msg = f'Table "{table_name}" not found in database.'
+            raise ValueError(msg) from e
+        raise
+
     cmd_output = cmd_output.decode(encoding)
     lines = cmd_output.splitlines()
     schema_ddl = "\n".join(line for line in lines if line and not line.startswith("-"))
 
     create_table_matches = CREATE_TABLE_RE.findall(schema_ddl)
+
+    # These failures are likely more related to implementation issues, and less
+    # about the table being missing.
     if len(create_table_matches) == 0:
         msg = f'Table schema "{table_name}" not found in "mdb-schema" output.'
         raise ValueError(msg)
     if len(create_table_matches) > 1:
-        msg = f'Multiple table schemas found for "{table_name}" in "mdb-schema" output.'
+        msg = (
+            f'Multiple table schemas found for "{table_name}" in "mdb-schema" output. '
+            "Logical error."
+        )
         raise ValueError(msg)
 
     table_name_mdb, defs = create_table_matches[0]

tests/test_read_table.py

@@ -2,6 +2,8 @@
 
 from pathlib import Path
 
+import pytest
+
 from polars_access_mdbtools import read_table
 
 
@@ -24,3 +26,13 @@ def test_can_read_all_tables_in_sample_db_1(sample_db_1: Path) -> None:
         assert df.height == expected_rows, (
             f"Table {table_name} should have {expected_rows} rows, but had {df.height}."
         )
+
+
+def test_read_nonexistent_table_raises_value_error(sample_db_1: Path) -> None:
+    """Test that reading a nonexistent table raises ValueError."""
+    nonexistent_table_name = "NONEXISTENT_TABLE"
+    with pytest.raises(
+        ValueError,
+        match=f'Table "{nonexistent_table_name}" not found in database',
+    ):
+        read_table(sample_db_1, nonexistent_table_name)