Session.add does not add auto-incrementing value id

[vinicius507]

Greetings,

I'm trying to setup tests in a FastAPI API that uses SQLAlchemy and I'm unable to test the creation of resources due to pydantic ValidationError.

# conftest.py
@pytest.fixture(scope="session")
def db() -> Session:
    return UnifiedAlchemyMagicMock()


@pytest.fixture(scope="session")
def test_app(db):
    def _get_db_override():
        return db

    app.dependency_overrides[get_db] = _get_db_override
    client = TestClient(app)
    return client

And the test:

def test_create_tags(test_app, faker):
    expected_tag = dict(id=1, name=faker.name(), description=faker.text())

    response = test_app.post("/tags/", json=expected_tag)

    assert response.status_code == 200
    assert response.json() == expected_tag

It gives the following error:

E               pydantic.error_wrappers.ValidationError: 1 validation error for Tag
E               response -> id
E                 none is not an allowed value (type=type_error.none.not_allowed)

Which leads me to believe that session.add with UnifiedAlchemyMagicMock does not work with auto-incrementing values such as id, in this case. What should I do?