test: add comprehensive tests for database.py and upload_to_email.py

- Added tests for database.py migration functions
- Added tests for error handling in init_db()
- Added tests for file path columns migration
- Added tests for unique index dropping
- Added tests for idempotent migrations
- Added tests for email template fallback logic
- Added tests for SVG logo attachment
- Added tests for SMTP without TLS and without auth
- Added tests for timeout errors in SMTP
- Added tests for upload_to_email task validation

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

tests/test_database.py

@@ -144,3 +144,174 @@ class TestSchemaMigrations:
         assert "detail" in columns
 
         engine.dispose()
+
+    def test_migration_adds_file_path_columns(self, tmp_path):
+        """Test that _run_schema_migrations adds file path columns to files table."""
+        from sqlalchemy import create_engine, text
+
+        from app.database import _run_schema_migrations
+
+        # Create a database with the old schema (no file path columns)
+        db_path = str(tmp_path / "migration_files_test.db")
+        engine = create_engine(f"sqlite:///{db_path}")
+        with engine.begin() as conn:
+            conn.execute(
+                text(
+                    "CREATE TABLE files ("
+                    "id INTEGER PRIMARY KEY, "
+                    "filename VARCHAR, "
+                    "filehash VARCHAR, "
+                    "upload_date DATETIME)"
+                )
+            )
+
+        # Run migrations
+        _run_schema_migrations(engine)
+
+        # Verify columns were added
+        from sqlalchemy import inspect
+
+        inspector = inspect(engine)
+        columns = [col["name"] for col in inspector.get_columns("files")]
+        assert "original_file_path" in columns
+        assert "processed_file_path" in columns
+        assert "is_duplicate" in columns
+        assert "duplicate_of_id" in columns
+
+        engine.dispose()
+
+    def test_migration_drops_unique_filehash_index(self, tmp_path):
+        """Test that _run_schema_migrations drops unique index on filehash."""
+        from sqlalchemy import create_engine, text
+
+        from app.database import _run_schema_migrations
+
+        # Create a database with unique index on filehash
+        db_path = str(tmp_path / "migration_index_test.db")
+        engine = create_engine(f"sqlite:///{db_path}")
+        with engine.begin() as conn:
+            conn.execute(
+                text(
+                    "CREATE TABLE files ("
+                    "id INTEGER PRIMARY KEY, "
+                    "filename VARCHAR, "
+                    "filehash VARCHAR, "
+                    "upload_date DATETIME, "
+                    "original_file_path VARCHAR, "
+                    "processed_file_path VARCHAR, "
+                    "is_duplicate BOOLEAN DEFAULT FALSE NOT NULL, "
+                    "duplicate_of_id INTEGER)"
+                )
+            )
+            conn.execute(text("CREATE UNIQUE INDEX idx_filehash_unique ON files (filehash)"))
+
+        # Verify unique index exists before migration
+        from sqlalchemy import inspect
+
+        inspector = inspect(engine)
+        indexes_before = inspector.get_indexes("files")
+        unique_indexes_before = [idx for idx in indexes_before if idx.get("unique")]
+        assert len(unique_indexes_before) > 0
+
+        # Run migrations
+        _run_schema_migrations(engine)
+
+        # Verify unique index was removed
+        inspector = inspect(engine)
+        indexes_after = inspector.get_indexes("files")
+        unique_filehash_indexes_after = [
+            idx for idx in indexes_after if idx.get("unique") and "filehash" in idx.get("column_names", [])
+        ]
+        assert len(unique_filehash_indexes_after) == 0
+
+        engine.dispose()
+
+    def test_migration_handles_missing_tables_gracefully(self, tmp_path):
+        """Test that migrations don't fail when tables don't exist."""
+        from sqlalchemy import create_engine
+
+        from app.database import _run_schema_migrations
+
+        # Create an empty database
+        db_path = str(tmp_path / "empty_db_test.db")
+        engine = create_engine(f"sqlite:///{db_path}")
+
+        # Run migrations - should not raise any errors
+        _run_schema_migrations(engine)
+
+        engine.dispose()
+
+    def test_migration_is_idempotent(self, tmp_path):
+        """Test that running migrations multiple times is safe."""
+        from sqlalchemy import create_engine, text
+
+        from app.database import _run_schema_migrations
+
+        # Create a database with old schema
+        db_path = str(tmp_path / "idempotent_test.db")
+        engine = create_engine(f"sqlite:///{db_path}")
+        with engine.begin() as conn:
+            conn.execute(
+                text(
+                    "CREATE TABLE processing_logs ("
+                    "id INTEGER PRIMARY KEY, "
+                    "file_id INTEGER, "
+                    "task_id VARCHAR, "
+                    "step_name VARCHAR, "
+                    "status VARCHAR, "
+                    "message VARCHAR, "
+                    "timestamp DATETIME)"
+                )
+            )
+            conn.execute(
+                text(
+                    "CREATE TABLE files ("
+                    "id INTEGER PRIMARY KEY, "
+                    "filename VARCHAR, "
+                    "filehash VARCHAR, "
+                    "upload_date DATETIME)"
+                )
+            )
+
+        # Run migrations multiple times
+        _run_schema_migrations(engine)
+        _run_schema_migrations(engine)
+        _run_schema_migrations(engine)
+
+        # Verify all columns exist and no errors occurred
+        from sqlalchemy import inspect
+
+        inspector = inspect(engine)
+        
+        processing_log_columns = [col["name"] for col in inspector.get_columns("processing_logs")]
+        assert "detail" in processing_log_columns
+
+        files_columns = [col["name"] for col in inspector.get_columns("files")]
+        assert "original_file_path" in files_columns
+        assert "processed_file_path" in files_columns
+        assert "is_duplicate" in files_columns
+        assert "duplicate_of_id" in files_columns
+
+        engine.dispose()
+
+
+@pytest.mark.unit
+class TestInitDbErrors:
+    """Tests for error handling in init_db function."""
+
+    @patch("app.database.Base")
+    @patch("app.database.make_url")
+    def test_init_db_handles_sqlalchemy_error(self, mock_make_url, mock_base):
+        """Test that init_db properly handles SQLAlchemy errors."""
+        from sqlalchemy import exc
+
+        # Mock to raise SQLAlchemy error
+        mock_url = MagicMock()
+        mock_url.get_backend_name.return_value = "sqlite"
+        mock_url.database = ":memory:"
+        mock_make_url.return_value = mock_url
+        
+        mock_base.metadata.create_all.side_effect = exc.SQLAlchemyError("Database error")
+
+        with pytest.raises(exc.SQLAlchemyError):
+            init_db()