Python模拟全局变量的list函数pytes

Question

当测试消息总线将调用在其全局变量中指定的函数时

消息总线.py

from . import handlers

class MessageBus:
    ...
    def handle_event(self, event: events.Event):
        handlers_ = EVENT_HANDLERS.get(type(event))
        ...

EVENT_HANDLERS = {
    events.BatchConfirmed: [handlers.send_remittance_to_connect, handlers.send_payment_information_to_vendor],
}

测试\u handlers.py

from . import messagebus

def test_payment_batch_confirm_calls_expected_handlers(mocker):  # using pytest
    # GIVEN mocked event handlers to isolate tests
    send_remittance_to_connect_mock = \
        mocker.patch('src.disbursement.messagebus.handlers.send_remittance_to_connect')
    send_payment_information_to_vendor_mock = \
        mocker.patch('src.disbursement.handlers.send_payment_information_to_vendor')
    create_import_je_mock = mocker.patch('src.disbursement.handlers.create_import_je')

    # GIVEN a payment batch with a confirmation
    bus = messagebus.MessageBus()

    # WHEN invoking the cli to add the confirmation number
    bus.handle(commands.ConfirmPaymentBatch(
        reference=batch.reference, confirmation='PR-234848-493333333',
        payment_date=pd.Timestamp(year=2019, month=11, day=23)
    ))

    # THEN the expected handlers are called
    assert send_remittance_to_connect_mock.called  # this fails even though it is in the dictionary's list
    assert send_payment_information_to_vendor_mock.called
    assert create_import_je_mock.called

上述测试失败，出现此错误

AssertionError: assert False
where False = <MagicMock name='send_remittance_to_connect' id='140228606012384'>.called

我希望它在最后一次断言时失败，因为修补的处理程序函数在EVENT_HANDLERS字典中。带着调试器。patch正在工作（底部紫色框）。当查看全局变量的函数时。然而，它并没有在messagebus类EVENT_HANDLER字典中填写。我认为问题是测试文件中的import语句在模拟函数之前加载了EVENT_HANDLERS全局字典值。因此，在实例化messagebus时不会替换它们。而且，这是唯一正在运行的测试，因此不会从其他测试中溢出任何内容

我正在研究monkey patching the EVENT_HANDLERS字典，但是测试正在研究这些被称为monkey patching的处理程序，从我所知道的，是否会破坏测试的目的。如何模拟这些函数，或者用什么方法来测试