minimal working example pytest fastapi multiprocessing (not working)

README.md

Minimal example to ask in StackOverflow

Pytest does not allow to start a process with a service and tests requests to it, at least not in the most straightforward way IMHO.

I may be missing something, or I may be doing something wrong. Hence, I share this short code in a gist, to ask.

How to run it

The dependencies are: fastapi pytest requests uvicorn. You may install them with your package / environment manager of choice, or use pipenv install with the provided Pipfile.

To run the code in the environment (e.g. pipenv shell), run: python3 mwe.py. You should see everything is OK.

To run the test, run in the environment: pytest. This does not work for me, the request times out.

mwe.py

import fastapi, multiprocessing, requests, time, uvicorn

app = fastapi.FastAPI()


@app.get('/ok')
def ok():
    return 'OK'


class service:
    def __enter__(self):
        def run_service(): uvicorn.run('mwe:app', host='0.0.0.0', port=8000, reload=True)
        self.service = multiprocessing.Process(target=run_service)
        self.service.start()
        time.sleep(10)

    def __exit__(self, *args):
        self.service.terminate()


def main():
    with service():
        return requests.get('http://127.0.0.1:8000/ok').ok


if __name__ == '__main__':
    print('🆖🆗'[main()])

Pipfile

[[source]]
url = "https://pypi.org/simple"
verify_ssl = true
name = "pypi"

[packages]
pytest = "*"
fastapi = "*"
requests = "*"
uvicorn = "*"

[requires]
python_version = "3.10"
python_full_version = "3.10.6"

test_mwe.py

from mwe import main

def test_main():
    assert main()