aiomock

a version of pythons unittest.Mock with async methods

This mock works exactly like unitest.mock.Mock, except that it also includes the following:

• mock.async_return_value - an awaitable version of return_value
• mock.async_side_effect - an awaitable version of side_effect

Tip

This project is likely not needed. Python 3.8 added an official AsyncMock object to the standard Library: https://docs.python.org/3.8/library/unittest.mock.html#unittest.mock.AsyncMock

installing

pip install aiomock

rational

imagine you have the following code

queue = asyncio.Queue()

async def wait_for_it():
    item = await queue.get()
    # do something with item
    return item

in order to test this, you cant use unittest.Mock.return_value because it is not awaitable. This means you have to write a function for every test

async def test_wait_for_it(monkeypatch):
    mock = Mock()
    async def my_get():
        return 1
    mock.get = my_get

    monkeypatch.setattr(asyncio.Queue, mock)

Its annoying that Mock has two excellant features, side_effect, and return, but you cant use them because we are async. This fixes that

Using

from aiomock import AIOMock

async def test_wait_for_it(monkeypatch):
    mock = AIOMock()
    mock.get.async_return_value = 1

    monkeypatch.setattr(asyncio.Queue, mock)

or for side_effect, use

mock.func_name.async_side_effect = [1, 2]

You can even use it with lambdas, and it will convert it to an awaitable

mock.func_name.async_side_effect = lambda x: x+4