模拟for循环中的open/file

Question

考虑模拟返回文件对象的打开调用

>>> from unittest.mock import MagicMock
>>> mock_fi = MagicMock()
>>> mock_op = MagicMock()  
>>> mock_op.return_value = mock_file
>>> 
>>> f = mock_op()
>>> f is mock_fi
True

到目前为止还不错。模拟调用的内容是

>>> mock_fi.mock_calls
[]
>>> mock_op.mock_calls
[call()]

这也很好。现在考虑在文件中的行上循环

>>> for l in mock_fi:
...     break
... 
>>> mock_fi.mock_calls
[call.__iter__()]

这是意料之中的。我不明白的是为什么mock\u op对象也记录了一个__iter__调用

>>> mock_op.mock_calls
[call(), call().__iter__()]

Answer 1

根据文档，mock_calls记录对对象的所有调用，以及对该对象的调用返回的对象

例如：

>>> my_mock = MagicMock()
>>> my_mock.foo().bar()
<MagicMock name='mock.foo().bar()' id='140397146563528'>
>>> my_mock.mock_calls
[call.foo(), call.foo().bar()] # bar() was not called directly on my_mock,
                               # yet, it is included since it was called on 
                               # the return value of foo() which is a direct 
                               # access to my_mock

在原始代码中，mock_op.mock_calls报告call().__iter__()，这是对mock_fi上__iter__()的调用