Flask测试期间如何回滚数据库更改

Question

When running tests in pytest, the database is modified. What is the best way to undo changes to the database?

DBSession rollback

For those tests where I can access the backend directly, I currently use pytest fixture to start a new DBSession for every test function, and rollback the session at the end of it

@pytest.fixture(scope='session')
def db(app, request):
    """Session-wide test database."""
    def teardown():
        pass

    _db = SQLAlchemy(app)    
    return _db

@pytest.fixture(scope='function')
def db_session(db, request):
    """Creates a new database session for a test."""
    engine = create_engine(
                            TestConfig.SQLALCHEMY_DATABASE_URI,
                            connect_args={"options": "-c timezone=utc"})
    DbSession = sessionmaker(bind=engine)
    session = DbSession()
    connection = engine.connect()
    transaction = connection.begin()
    options = dict(bind=connection, binds={})
    session = db.create_scoped_session(options=options)
    db.session = session

    yield session

    transaction.rollback()
    connection.close()
    session.remove()

In the test code, I simply use the fixture

def test_create_project(db_session): project = _create_test_project(db_session) assert project.project_id > 0

Flask / HTTP Testing

But for testing the API via Flask/HTTP, I cannot use db_session . Even when I create a fixture to explicitly DROP the test database and restore from production, it will not work because there is no direct database code

@pytest.fixture(scope='function')
def db_session_refresh(db, request):
    """Refresh the test database from production after running the test"""
    engine = create_engine(
                            TestConfig.SQLALCHEMY_DATABASE_URI,
                            connect_args={"options": "-c timezone=utc"})
    DbSession = sessionmaker(bind=engine)
    session = DbSession()

    connection = engine.connect()
    transaction = connection.begin()

    options = dict(bind=connection, binds={})
    session = db.create_scoped_session(options=options)

    db.session = session

    yield session

    transaction.rollback()
    connection.close()
    session.remove()  
    refresh_test_db_sql = """
        SELECT pg_terminate_backend(pid)
        FROM pg_stat_activity
        WHERE datname = 'appdb_test';

        DROP DATABASE appdb_test;

        CREATE DATABASE appdb_test TEMPLATE appdb;
        """
    engine.execute(refresh_test_db_sql)

Even if this works, it is inefficient to refresh the database for every function.

What is the proper/better way to run test that modifies the database?

Answer 1

as commented earlier - creation and destruction of the DB should be taken care out of you unit test and moved into a wrapper.

but to answer you question - I have the impression that you're using postgresql. try removing the database name from your connection string and connect to it directly and add it to the search_path