Testing

As we learned in Chapter 3, Coding, Testing, and Documentation: the Virtuous Cycle, the biggest challenge when writing functional tests for a service that calls other services is to isolate all network calls. In this section, we'll see how we can mock asynchronous calls made using aiohttp.

Testing aiohttp and its outgoing web requests involves a different approach to traditional synchronous tests. The aioresponses project (https://github.com/pnuckowski/aioresponses) allows you to easily create mocked responses to web requests made using an aiohttp ClientSession:

# test_aiohttp_fixture.py
import asyncio
import aiohttp
import pytest
from aioresponses import aioresponses
@pytest.fixture
def mock_aioresponse():
    with aioresponses() as m:
        yield m
@pytest.mark.asyncio
async def test_ctx(mock_aioresponse):
    async with aiohttp.ClientSession() as session:
        mock_aioresponse.get("http://test.example.com", payload={"foo": "bar...