test: Add mock tests reproducing Snowflake duplicate constraint bugs to fix #26199

Author: aniruddhaadak80

ingestion/tests/unit/topology/database/test_snowflake_constraints.py

@@ -0,0 +1,53 @@
+from unittest.mock import Mock
+from metadata.ingestion.source.database.snowflake.utils import _get_schema_unique_constraints
+
+def test_snowflake_unique_constraint_collision():
+    # Mocking self (SnowflakeDialect)
+    dialect_mock = Mock()
+    dialect_mock.normalize_name = lambda name: name.lower() if name else name
+
+    # Mocking connection
+    connection_mock = Mock()
+
+    # Mocking the result of connection.execute(...)
+    # Simulating two tables 'table_1' and 'table_2' inside the same schema 
+    # both sharing an identical constraint name like "unique_id"
+    row1 = Mock()
+    row1._mapping = {
+        "constraint_name": "unique_id",
+        "table_name": "table_1",
+        "column_name": "id"
+    }
+
+    row2 = Mock()
+    row2._mapping = {
+        "constraint_name": "unique_id",
+        "table_name": "table_2",
+        "column_name": "id"
+    }
+    
+    # Composite constraint on table_2 (second column of the same unique key)
+    row3 = Mock()
+    row3._mapping = {
+        "constraint_name": "unique_id",
+        "table_name": "table_2",
+        "column_name": "email"
+    }
+
+    result_mock = [row1, row2, row3]
+    connection_mock.execute.return_value = result_mock
+
+    # Run the patched function
+    output = _get_schema_unique_constraints(dialect_mock, connection_mock, "public")
+
+    # Output should correctly split the constraints for table_1 and table_2 without collision
+    assert "table_1" in output
+    assert "table_2" in output
+
+    assert len(output["table_1"]) == 1
+    assert output["table_1"][0]["name"] == "unique_id"
+    assert output["table_1"][0]["column_names"] == ["id"]
+
+    assert len(output["table_2"]) == 1
+    assert output["table_2"][0]["name"] == "unique_id"
+    assert output["table_2"][0]["column_names"] == ["id", "email"]