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pytest event loop is already running

See original GitHub issue

Because the test client calls loop.run_until_complete(connection(receive, send)), I cannot use anything that modifies the event loop in a pytest fixture without getting RuntimeError: This event loop is already running.

I would like to use a package like aresponses to mock aiohttp requests like this:

@pytest.fixture
def mock_endpoint(aresponses):
    aresponses.add('mock.com', '/test/', 'get', 'this is my mock response')

After messing with it for a couple hours, the only way I was able to get successful tests was to wrap the application in middleware:

@pytest.fixture
def app():
    class App:
        def __init__(self, app):
            self.app = app

        def __call__(self, scope):
            return functools.partial(self.asgi, scope=scope)

        async def asgi(self, receive, send, scope):
            async with ResponsesMockServer() as aresponses:
                aresponses.add('mock.com', '/test/', 'get', 'this is my mock response')
                inner = self.app(scope)
                await inner(receive, send)
    return App(application)


@pytest.fixture
def test_client(app):
    with TestClient(app) as test_client:
        yield test_client

I am going to modify this to allow myself to dynamically pass responses through the @pytest.mark decorator, but this workflow is not really convenient at all.

Am I missing something here? Is there a better way to set up my test clients, or should I just keep going down this route?

Thanks

Issue Analytics

State:
Created 5 years ago
Reactions:6
Comments:22 (7 by maintainers)

Top GitHub Comments

13reactions

teskjecommented, Jun 27, 2019

Just FYI, I’m also stumbling over this currently trying to use the TestClient in an async test function (with pytest-asyncio). Minimal test case:

import pytest
from starlette.responses import HTMLResponse
from starlette.testclient import TestClient

async def app(scope, receive, send):
    assert scope['type'] == 'http'
    response = HTMLResponse('<html><body>Hello, world!</body></html>')
    await response(scope, receive, send)

@pytest.mark.asyncio
async def test_app():
    client = TestClient(app)
    response = client.get('/')
    assert response.status_code == 200

Fails with “RuntimeError: This event loop is already running” too. I guess there is currently no workaround, aside from just not using async tests, which I think wouldn’t work in my specific case.

Thank you for working on this!

7reactions

taybincommented, Sep 12, 2019

I have a similar problem where I’m also trying to embed a database connection with a transaction active for the current test in the request.state. I haven’t quite found the magic configuration of pytest, pytest-asyncio, and TestClient to make this work yet.

Basically, I’d love to see an example of how to use TestClient along with databases/asyncpg.