Feature: pytest-compatible mocks for supported integrations

[fubuloubu]

Would be nice to have some easy, out-of-the-box implementations that work well with how you would typically test an integration that this Fief client ships with (FastAPI, Flask, or the library behind a Python CLI). This could even completely elide Fief in the test scenario where I want to just inject fake auth data (typically, in testing I don't necessarily care about using my real auth service data, which is separate anyways). Still thinking through what would be best for this, this is my sketch (I am using it with a few FastAPI services and a SDK/CLI python package)

FastAPI testing:

# `tests/conftest.py`
import pytest
from fief_client.integrations.fastapi import MockFiefAuth

from myapp import app, auth


@pytest.fixture()
def client():
    # Adapted from https://sqlmodel.tiangolo.com/tutorial/fastapi/tests/
    app.dependency_overrides[auth] = MockFiefAuth()
    yield TestClient(app)
    app.dependency_overrides.clear()

For CLI testing, I'm not sure I have a well-formed need yet, but it might be good to implement something useful with how Click does testing

[frankie567]

For testing with FastAPI, I would recommend to just override the dependency. FiefUserInfo is a simple dictionary, so you can do something like this:

current_user = auth.current_user()

@app.get("/protected", name="protected")
async def protected(
    user: FiefUserInfo = Depends(current_user),  
):
    return HTMLResponse(
        f"<h1>You are authenticated. Your user email is {user['email']}</h1>"
    )

mock_user = {
    "sub": "aeeb8bfa-e8f4-4724-9427-c3d5af66190e",
    "email": "anne@bretagne.duchy",
    "tenant_id": "c91ecb7f-359c-4244-8385-51ecd6c0d06b",
    "fields": {
        "first_name": "Anne",
        "last_name": "De Bretagne"
    }
}

app.dependency_overrides[current_user] = lambda: mock_user

[fubuloubu]

In that example, current_user is an object refetence? I wonder if a slight rearchitecure might make it clearer how to do that for this purpose, because auth.current_user() isn't possible to override

Would Depends(auth.current_user) also function with how the client works currently? I think it would be possible to do a dependency override on that

[fubuloubu]

Also, for reference what I did was make an override where it checks the request.headers for a special test-only header containing a user ID, and check that against my UserInfo cache db table for more "representative" testing

[frankie567]

Yeah, the thing is, since FastAPI dependency_overrides works by reference, you'll need to create a strong reference to your dependency instance to make it work. That's why I added current_user = auth.current_user().

Also, for reference what I did was make an override where it checks the request.headers for a special test-only header containing a user ID, and check that against my UserInfo cache db table for more "representative" testing

Yes, that works too :)