Bug: when using TestClient for testing an endpoint

[dnutiu]

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Example Code

@pytest.mark.asyncio
async def test_something(test_client):
    response = test_client.get("/v1/rules/?custom=example.com&args=0&kwargs=0")
    assert response is not None

Description

I need to pass args and kwargs otherwise the test client returns 422. I've encountered the bug before where the test client returned 422 when x was not passed.

Operating System

macOS

Operating System Details

No response

FastAPI Version

0.110.2

Pydantic Version

2.7.0

Python Version

Python 3.12.1

Additional Context

b'{"detail":[{"type":"missing","loc":["query","args"],"msg":"Field required","input":null},{"type":"missing","loc":["query","kwargs"],"msg":"Field required","input":null}]}'

[dnutiu]

So basically parameters defined in dependency overrides get picked up as query parameters:

def auth_service_mock_dependency(x):
  pass

api_client.app.dependency_overrides[authentication_service] = auth_service_mock_dependency

[YuriiMotov]

What is x?
You have to specify the type of this parameter and where FastAPI should look for it (Query, Path, Body, etc.)

[YuriiMotov]

Please, in order to get help, provide the signatures of the endpoint function you are trying to test and its dependencies (including dependency overrides)

[dnutiu]

The dependency override has the following signature:

async def authentication_service(app_settings: Annotated[Settings, Depends(settings)]):

And the function I'm trying to test:

@router.get(...)
async def get_rule(
    domain: Annotated[
        str, Query(..., description="The domain associated with the rule.", min_length=1)
    ],
    auth_service: Annotated[AuthenticationService, Depends(authentication_service)],
):

I see now why that happens, since x is just a placeholder for the settings dependency in the mocked authentication service dependency it gets picked up as a query parameter by FastAPI when it gets overridden by the test:

def auth_service_mock_dependency(x):
  pass

api_client.app.dependency_overrides[authentication_service] = auth_service_mock_dependency