模拟：跟踪所有呼叫。外壳与程序不一致答案

【问题标题】：Mock: Tracking all Calls. Shell vs. program inconsistency模拟：跟踪所有呼叫。外壳与程序不一致
【发布时间】：2014-05-24 15:55:27
【问题描述】：

为什么 mock.mock_calls 的内容会根据我是在 shell 中运行还是在一个程序中？ mock.mock_calls == expected 的断言在程序中失败，但在 shell 中通过。该代码基于用于跟踪多个呼叫的文档。 (26.5.1.5. Tracking all Calls)

>>> from unittest.mock import MagicMock, call
>>> mock = MagicMock()
>>> mock.method()
<MagicMock name='mock.method()' id='57725952'>
>>> mock.attribute.method(10, x=53)
<MagicMock name='mock.attribute.method()' id='57775944'>
>>> mock.mock_calls
[call.method(), call.attribute.method(10, x=53)]
>>> mock.method_calls
[call.method(), call.attribute.method(10, x=53)]
>>> expected = [call.method(), call.attribute.method(10, x=53)]
>>> expected == mock.mock_calls
True
>>> expected == mock.method_calls
True

到目前为止，这一切都完全符合预期。但是看看程序中mock.mock_calls 会发生什么：它记录对每个调用方法的__str__ 方法的额外调用。 mock.method_calls 不受影响。

import unittest.mock
mock = unittest.mock.MagicMock()
print(mock.method())
print(mock.attribute.method(10, x=53))
print('\nmock.mock_calls\n', mock.mock_calls)
print('\nmock.method_calls\n', mock.method_calls)

expected = [unittest.mock.call.method(),
            unittest.mock.call.attribute.method(10, x=53)]
print(expected == mock.mock_calls)
print(expected == mock.method_calls)

输出：

<MagicMock name='mock.method()' id='45740272'>
<MagicMock name='mock.attribute.method()' id='45850128'>

mock.mock_calls
 [call.method(),
 call.method().__str__(),
 call.attribute.method(10, x=53),
 call.attribute.method().__str__()]

mock.method_calls
 [call.method(), call.attribute.method(10, x=53)]
False
True

我在 Windows 7 计算机上运行 Python 3.4。

【问题讨论】：

标签： python unit-testing python-3.x mocking python-mock

【解决方案1】：

这是因为您正在打印方法调用。它会导致调用 __str__() 魔术方法：

print(mock.method())
print(mock.attribute.method(10, x=53))

消除print() 调用，您将看到所需的行为：

mock.method()
mock.attribute.method(10, x=53)

仅供参考，来自控制台的示例：

>>> mock = unittest.mock.MagicMock()
>>> print(mock.method())
<MagicMock name='mock.method()' id='4433183576'>
>>> print(mock.attribute.method(10, x=53))
<MagicMock name='mock.attribute.method()' id='4433223752'>
>>> mock.mock_calls
[call.method(),
 call.method().__str__(),
 call.attribute.method(10, x=53),
 call.attribute.method().__str__()]

或者，或者，使用普通的Mock 类：

>>> mock = unittest.mock.Mock()
>>> print(mock.method())
<Mock name='mock.method()' id='4433235528'>
>>> print(mock.attribute.method(10, x=53))
<Mock name='mock.attribute.method()' id='4433252648'>
>>> mock.method_calls
[call.method(), call.attribute.method(10, x=53)]
>>> mock.mock_calls
[call.method(), call.attribute.method(10, x=53)]

【讨论】：