python - 如何在单元测试期间验证 Mock mock_calls 列表中的 .__getitem__() 调用

Question

当尝试对返回元组的方法进行单元测试并且我试图查看代码是否访问正确的元组索引时，python 尝试评估预期的调用并将其转换为字符串。

call().methodA().__getitem__(0) 最终被转换为 '().methodA' 在我的 expected_calls 断言列表中。

提供的示例代码产生输出和回溯:

expected_calls=[call().methodA(), '().methodA']
  result_calls=[call().methodA(), call().methodA().__getitem__(0)]
======================================================================
ERROR: test_methodB (badMockCalls.Test_UsingToBeMocked_methods)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\dev\workspace\TestCode\src\badMockCalls.py", line 43, in test_methodB
    self.assertListEqual(expected_calls, self.result_calls)
  File "C:\Python33\lib\unittest\case.py", line 844, in assertListEqual
    self.assertSequenceEqual(list1, list2, msg, seq_type=list)
  File "C:\Python33\lib\unittest\case.py", line 764, in assertSequenceEqual
    if seq1 == seq2:
  File "C:\Python33\lib\unittest\mock.py", line 1927, in __eq__
    first, second = other
ValueError: too many values to unpack (expected 2)

----------------------------------------------------------------------
Ran 1 test in 0.006s

FAILED (errors=1)

如何断言方法 B 正在调用 self.tbm.methodA()[0] 合适吗？

示例代码(Python 3.3.2):

import unittest
from unittest.mock import call, patch
import logging

log = logging.getLogger(__name__)
log.setLevel(logging.DEBUG)
_ch = logging.StreamHandler()
_ch.setLevel(logging.DEBUG)
log.addHandler(_ch)

class ToBeMocked():  # external resource that can't be changed
    def methodA(self):
        return (1,)

class UsingToBeMocked():  # project code
    def __init__(self):
        self.tbm = ToBeMocked()

    def methodB(self):
        value = self.tbm.methodA()[0]
        return value

class Test_UsingToBeMocked_methods(unittest.TestCase):
    def setUp(self):
        self.patcher = patch(__name__ + '.ToBeMocked')
        self.mock_ToBeMocked = self.patcher.start()
        self.utbm = UsingToBeMocked()
        # clear out the mock_calls list from the constructor calls
        self.mock_ToBeMocked.mock_calls = []
        # set result to always point to the mock_calls that we are testing
        self.result_calls = self.mock_ToBeMocked.mock_calls

    def tearDown(self):
        self.patcher.stop()

    def test_methodB(self):
        self.utbm.methodB()
        # make sure the correct sequence of calls is made with correct parameters
        expected_calls = [call().methodA(),
                          call().methodA().__getitem__(0)]
        log.debug('expected_calls=' + str(expected_calls))
        log.debug('  result_calls=' + str(self.result_calls))
        self.assertListEqual(expected_calls, self.result_calls)

if __name__ == "__main__":
    unittest.main()

Answer 1

测试 mock_object.account['xxx1'].patch(body={'status': 'active'}) 我不得不使用测试:

mock_object.account.__getitem__.assert_has_calls([
    call('xxxx1'),
    call().patch(body={'status': 'active'}),
])

我无法解释为什么会这样，这看起来很奇怪，可能是 mock 中的错误，但我一直得到这些结果并且它有效。