How do I Mock the coroutine json() when using aiohttp.ClientSession.get

Question

I want to mock the json() coroutine from the aiohttp.ClientSession.get method. It looks to return an async generator object, which is where I'm confused on how to mock in my example. Here is my code:

async def get_access_token():

async with aiohttp.ClientSession(auth=auth_credentials) as client:
    async with client.get(auth_path, params={'grant_type': 'client_credentials'}) as auth_response:
        assert auth_response.status == 200
        auth_json = await auth_response.json()
        return auth_json['access_token']

This is my test case to mock the get method:

json_data = [{
'access_token': 'HSG9hsf328bJSWO82sl',
'expires_in': 86399, 
'token_type': 'bearer'
}]

class AsyncMock:
    async def __aenter__(self):
        return self

    async def __aexit__(self, *error_info):
        return self

@pytest.mark.asyncio
async def test_wow_api_invalid_credentials(monkeypatch, mocker):
    def mock_client_get(self, auth_path, params):
        mock_response = AsyncMock()
        mock_response.status = 200
        mock_response.json = mocker.MagicMock(return_value=json_data)
        return mock_response

    monkeypatch.setattr('wow.aiohttp.ClientSession.get', mock_client_get)
    result = await wow.get_access_token()

assert result == 'HSG9hsf328bJSWO82sl'

I think the problem might be that mock_response.json() is not awaitable. In my example I can't call await from a non async function so I'm confused on how I would do that. I would like to keep the test libraries to a minimum which is pytest and pytest-asyncio for the learning experiencing and to rely less on 3rd party libraries.

Answer 1

I was making it more complicated than it needed to be. I simply defined json as an awaitable attribute of AsyncMock which returns the json_data. The complete code looks like this:

json_data = {
'access_token': 'HSG9hsf328bJSWO82sl',
'expires_in': 86399, 
'token_type': 'bearer'
}

 class AsyncMock:
    async def __aenter__(self):
        return self

    async def __aexit__(self, *error_info):
        return self

    async def json(self):
        return json_data

@pytest.mark.asyncio
async def test_wow_api_invalid_credentials(monkeypatch):
    def mock_client_get(self, auth_path, params):
        mock_response = AsyncMock()
        mock_response.status = 200
        return mock_response

    monkeypatch.setattr('wow.aiohttp.ClientSession.get', mock_client_get)
    result = await wow.get_access_token()

    assert result == 'HSG9hsf328bJSWO82sl'