Question

我有一个使用aiohttp在WebSocket上监听消息的代码。

看起来像：

async for msg in ws:
    await self._ws_msg_handler.handle_message(ws, msg, _services)

其中ws是aiohttp.web.WebSocketResponse()（original code）

的实例

在我的测试中，我模拟了WebSocketResponse()及其__aiter__方法：

def coro_mock(**kwargs):
    return asyncio.coroutine(mock.Mock(**kwargs))


@pytest.mark.asyncio
@mock.patch('aiojsonrpc.request_handler.WebSocketMessageHandler')
async def test_rpc_websocket_handler(
    MockWebSocketMessageHandler,
    rpc_websocket_handler
):

    ws_response = 'aiojsonrpc.request_handler.WebSocketResponse'
    with mock.patch(ws_response) as MockWebSocketResponse:
        MockRequest = mock.MagicMock()
        req = MockRequest()

        ws_instance = MockWebSocketResponse.return_value
        ws_instance.prepare = coro_mock()
        ws_instance.__aiter__ = coro_mock(return_value=iter(range(5)))
        ws_instance.__anext__ = coro_mock()

        handle_msg_result = 'Message processed'
        MockWebSocketMessageHandler.handle_message.side_effect = Exception(
            handle_msg_result)
        msg_handler = MockWebSocketMessageHandler()

        with pytest.raises(Exception) as e:
            await request_handler.RpcWebsocketHandler(msg_handler)(req)
        assert str(e.value) == handle_msg_result

虽然当我运行test时它失败并显示错误消息：

＆＃39; async for＆＃39;需要一个__aiter__方法的对象，得到MagicMock

=================================================================================== FAILURES ===================================================================================
__________________________________________________________________________ test_rpc_websocket_handler __________________________________________________________________________

MockWebSocketMessageHandler = <MagicMock name='WebSocketMessageHandler' id='140687969989632'>
rpc_websocket_handler = <aiojsonrpc.request_handler.RpcWebsocketHandler object at 0x7ff47879b0f0>

    @pytest.mark.asyncio
    @mock.patch('aiojsonrpc.request_handler.WebSocketMessageHandler')
    async def test_rpc_websocket_handler(
        MockWebSocketMessageHandler,
        rpc_websocket_handler
    ):

        ws_response = 'aiojsonrpc.request_handler.WebSocketResponse'
        with mock.patch(ws_response) as MockWebSocketResponse:
            # MockRequest = mock.create_autospec(aiohttp.web_reqrep.Request)
            # req = MockRequest(*[None] * 6)
            MockRequest = mock.MagicMock()
            req = MockRequest()

            ws_instance = MockWebSocketResponse.return_value
            ret = mock.Mock()
            ws_instance.prepare = coro_mock()
            ws_instance.__aiter__ = coro_mock(return_value=iter(range(5)))
            ws_instance.__anext__ = coro_mock()

            handle_msg_result = 'Message processed'
            MockWebSocketMessageHandler.handle_message.side_effect = Exception(
                handle_msg_result)
            msg_handler = MockWebSocketMessageHandler()

            with pytest.raises(Exception) as e:
                await request_handler.RpcWebsocketHandler(msg_handler)(req)
>           assert str(e.value) == handle_msg_result
E           assert "'async for' ...got MagicMock" == 'Message processed'
E             - 'async for' requires an object with __aiter__ method, got MagicMock
E             + Message processed

tests/test_request_handler.py:252: AssertionError

所以它的行为就像__aiter__()从未被嘲笑过。在这种情况下，我应该如何完成正确的嘲弄？

更新

目前我已找到一个workaround来使代码可以测试，但如果有人告诉我如何处理原始问题中描述的问题，我真的很感激。

Answer 1

您可以使模拟类返回实现预期接口的对象：

class AsyncIterator:
    def __init__(self, seq):
        self.iter = iter(seq)

    async def __aiter__(self):
        return self

    async def __anext__(self):
        try:
            return next(self.iter)
        except StopIteration:
            raise StopAsyncIteration

MockWebSocketResponse.return_value = AsyncIterator(range(5))

我认为还没有一种方法可以正确地模拟实现__aiter__的对象，它可能是一个python错误，因为async for拒绝MagicMock，即使hasattr(the_magic_mock, '__aiter__')为True。

EDIT（13/12/2017）：库异步测试支持异步迭代器和上下文管理器，因为0.11，asynctest.MagicMock免费提供此功能。

Answer 2

为了后代，我遇到了需要测试async for循环的问题，但是公认的解决方案似乎不适用于Python 3.7。以下示例适用于3.6.x和3.7.0，但不适用于的{em} ：

3.5.x

使用上面的方法，模拟它类似于：

import asyncio


class AsyncIter:    
    def __init__(self, items):    
        self.items = items    

    async def __aiter__(self):    
        for item in self.items:    
            yield item    


async def print_iter(items):
    async for item in items:
        print(item)


if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    things = AsyncIter([1, 2, 3])
    loop.run_until_complete(print_iter(things))
    loop.close()

Answer 3

适用于py38

Range("A1").FormulaLocal = "=Somme(A2;A5)"

Python asyncio：如何模拟aiter （）方法？

3 个答案:

Python asyncio：如何模拟__aiter __（）方法？

3 个答案:

Python asyncio：如何模拟aiter （）方法？