I'm reading the database testing with SQLmodel chapter and try to reproduce the testings with fixtures approach.

My code is identical with the provided examples, but for a reason, my test is unable to use the mocked session that I give. This is my code :

main.py

settings = Settings()
app = FastAPI()

app.add_middleware(CORSMiddleware, allow_origins=settings.allowed_origins, allow_credentials=True, allow_methods=["*"], allow_headers=["*"])

app.include_router(router)
add_pagination(app)

my endpoint

from database import get_session

@router.get("")
def get_lexicon_entry(id: int, session: Session = Depends(get_session)):

    lex = session.exec(select(lxmodel).where(lxmodel.id == id)).first()
    return lex

my test file (/tests)

from database import get_session

@pytest.fixture(name="session")
def session_fixture():
    print("session_fixture")
    engine = create_engine(
        "sqlite:///testing.db", connect_args={"check_same_thread": False}
    )
    SQLModel.metadata.create_all(engine)
    with Session(engine) as session:
        yield session


def test_get_lexicon_entry(session: Session):

    def get_session_override():
        return session

    app.dependency_overrides[get_session] = get_session_override
    client = TestClient(app)
    response = client.get("/lexicon/entry?id=50")
    assert response.status_code == 404
    app.dependency_overrides.clear()

database.py

# ...engine declaration details...

def get_session():
    with Session(engine) as session:
        yield session

The response has a 200 status, so, the assertion raises an error. When I print the response with print(response.json()) it shows an entry that is in my production db.

When I run the test, the testing db is created; and when I check the content of the db, it is empty. This seem to indicates that the dependency is not correctly override.

I'm I missing something ?

Thank you in advance.

FastAPI version : latest

I'm reading the database testing with SQLmodel chapter and try to reproduce the testings with fixtures approach.

My code is identical with the provided examples, but for a reason, my test is unable to use the mocked session that I give. This is my code :

main.py

settings = Settings()
app = FastAPI()

app.add_middleware(CORSMiddleware, allow_origins=settings.allowed_origins, allow_credentials=True, allow_methods=["*"], allow_headers=["*"])

app.include_router(router)
add_pagination(app)

my endpoint

from database import get_session

@router.get("")
def get_lexicon_entry(id: int, session: Session = Depends(get_session)):

    lex = session.exec(select(lxmodel).where(lxmodel.id == id)).first()
    return lex

my test file (/tests)

from database import get_session

@pytest.fixture(name="session")
def session_fixture():
    print("session_fixture")
    engine = create_engine(
        "sqlite:///testing.db", connect_args={"check_same_thread": False}
    )
    SQLModel.metadata.create_all(engine)
    with Session(engine) as session:
        yield session


def test_get_lexicon_entry(session: Session):

    def get_session_override():
        return session

    app.dependency_overrides[get_session] = get_session_override
    client = TestClient(app)
    response = client.get("/lexicon/entry?id=50")
    assert response.status_code == 404
    app.dependency_overrides.clear()

database.py

# ...engine declaration details...

def get_session():
    with Session(engine) as session:
        yield session

The response has a 200 status, so, the assertion raises an error. When I print the response with print(response.json()) it shows an entry that is in my production db.

When I run the test, the testing db is created; and when I check the content of the db, it is empty. This seem to indicates that the dependency is not correctly override.

I'm I missing something ?

Thank you in advance.

FastAPI version : latest

• database
• testing
• mocking
• dependencies
• fastapi

1 Answer 1

The problem was coming from the routes param on the FastAPI class in the main.py file.

app = FastAPI(
    title="title",
    description="API",
    version="0.2",
    servers=[{"url": "http://localhost:8000", "description": "Localhost"}],
    routes=router.routes, # don't use that !
...
)

When the param is removed, the dependencies are effectively overridden by the fixtures and tests can run with the appropriate session.

I don't know if this a FastAPI issue.