Dependency override not working

[chrobotm]

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Example Code

from fastapi import APIRouter, Depends
from ..dependencies.get_user import get_user

router = APIRouter()

@router.post("")
async def my_func(user: str = Depends(get_user)):
     ...
    return {...}

Description

I'm trying to run some tests with pytest against the API but my dependency override is not working. It still tries to run the function as if there was no override. All other tests where we don't need to override a dependency work fine

tf/python/api/dependencies/get_user.py

from fastapi import Header
from typing import Union


def get_user(xyz: Union[str, None] = Header(default=...)):
    return ...

tf/python/api/endpoints/myfile.py

from fastapi import APIRouter, Depends
from ..dependencies.get_user import get_user

router = APIRouter()

@router.post("")
async def my_func(user: str = Depends(get_user)):
     ...
    return {...}

tf/python/api/tests/test_myfile.py

import responses

from fastapi.testclient import TestClient
from ...main import app
from ..dependencies.get_user import get_user

def override_get_user():
    return "asdf"

app.dependency_overrides[get_user] = override_get_user

client = TestClient(app)

def test_my_func():
    resp = client.post("/api/...", headers={"xyz": "dummy"})
    assert resp.status_code == 200
    assert resp.json() == {...}

Operating System

macOS

Operating System Details

No response

FastAPI Version

0.78.0

Python Version

3.9.13

Additional Context

No response

[jonatasoli]

You need use dependency_overrides before declare TestClient.

[chrobotm]

Thanks, I've just tried that but it didn't work either. I've updated the main post with your suggestion

[chrobotm]

in tf/python/api/tests/test_myfile.py, importing:

from api.dependencies.get_user import get_user

instead of:

from ..dependencies.get_user import get_user

seems to have done the trick

[dctaf]

This fixed my problem. This should be mentioned in the documentation.

[ekivolowitz]

@chrobotm thank you for putting an end to two days of debugging dependency injections. Just needed to find the right comment :(

[netanel-haber]

If anyone has more trouble with this: Mounted sub apps using e.g.:

app.mount(path, subapp)

won't inherit dependency_overrides and will need to have the overrides registered again manually.

[SayeedKhan21]

hey everyone I'm having a similar issue where I am trying to test reading a user at /users endpoint ,however the app seems to read from real db rather than test db , the override_get_db doesn't seem to run . Any suggestions ?

[rubywwwilde]

I believe the issue is that you are importing your dependency not from the original location.
For example here is my original get_db dependency location
from app.database import get_db

Before that I tried to import it from app.main or app.dependency and it failed

I would be very grateful if someone explains, why this actually happens! 🙏🏼

[SayeedKhan21]

hey man, i haven't really worked on the code since i posted this issue, however i do remember that changing some import statements did affect the way it worked, but don't know why , would be great if someone would clear it out

[fabianfalon]

Can you try something like that?

def override_get_user():
    return "asdf"


class TestApi:
    app.dependency_overrides[get_user] = override_get_user
    client = TestClient(app)

class TestHealthcheck(TestApi):
    def test_healthcheck(self):
        response = self.client.get("/healthcheck")
        assert response.status_code == 200