无法使用__exit__方法创建模拟模仿

Question

我无法在测试中将__exit__方法附加到模拟量模拟上，以便在with语句中使用该模拟时不介意。

这里是不断提高AttributeError: __exit__的测试示例：

# main.py
class FooManager(object):
    def __enter__(self):
        print "Connect"
    def __exit__(self, exc_type, exc_val, exc_tb):
        print "Dissconnect"
    def foo(self):
        print "Foo"    

def function_to_be_tested(manager):
    # type: (FooManager) -> None
    with manager:
        manager.foo()

# test.py
from mockito import mock, verify, when, any as ANY

def test():
    manager_mock = mock()

    # none of this has any effect:
    manager_mock.__exit__ = lambda a, b, c: None
    when(manager_mock).__exit__(ANY(), ANY(), ANY()).thenReturn(None)

    function_to_be_tested(manager_mock)
    verify(manager_mock, times=1).foo()

解决我的问题的唯一方法是：

class ContextManagerMock(mock):
    def __enter__(self):
        return None
    def __exit__(self, exc_type, exc_val, exc_tb):
        return None

def test():
    manager_mock = ContextManagerMock()
    function_to_be_tested(manager_mock)
    verify(manager_mock, times=1).foo()

但是，我想知道，当我尝试通过AttributeError函数或使用lambda函数附加__exit__方法时，为什么会有when。

Answer 1

[您可能只是想念也需要模拟__enter__。

In [24]: m = mock()

In [25]: when(m).__enter__(...)
Out[25]: <mockito.invocation.AnswerSelector at 0x13db478>

In [26]: when(m).__exit__(...)
Out[26]: <mockito.invocation.AnswerSelector at 0x501bd00>

In [27]: with m: ...

In [28]: verify(m).__enter__()

In [29]:

如果我不模拟__enter__，我会得到一个AttributeError: __enter__。