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嘿，我刚刚开始使用 Python 中的单元测试和模拟。尝试测试一个函数，该函数采用单列数据框并在根据数据框值进行一些计算后返回一个浮点数。

import unittest
from unittest.mock import MagicMock

def avg_annual_fcf_growth_rate(fcf_data_frame):
    delta = fcf_data_frame.iloc[9][0] - fcf_data_frame.iloc[0][0]
    avg_growth_rate = (delta**(1/9))-1 
    return avg_growth_rate

class Test_DCF(unittest.TestCase):

    def test_fcf_calculation(self):
        mock_fcf = MagicMock()
        mock_fcf.iloc[9][0].return_value = 100
        mock_fcf.iloc[0][0].return_value = 10
        result = avg_annual_fcf_growth_rate(mock_fcf)
        expected = ((100-10)**(1/9)) - 1
        self.assertEqual(result, expected)

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

#Sample dataframe 
         Free Cash Flow USD Mil
2008-12                  5114.0
2009-12                 10909.0
2010-12                 11915.0
2011-12                 12285.0
2012-12                 11175.0
2013-12                 16617.0
2014-12                 16825.0
2015-12                 15409.0
2016-12                 19581.0
2017-12                 34068.0

我遇到了一个问题，结果是 MagicMock 对象而不是浮点数。我尝试寻找答案，但无法理解如何正确设置模拟对象的返回值。

运行测试的输出。

F
======================================================================
FAIL: test_fcf_calculation (__main__.Test_DCF)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "path/to/intrinsic_value_dcf_test.py", line 18, in test_fcf_calculation
    self.assertEqual(result, expected)
AssertionError: <MagicMock name='mock.iloc.__getitem__().[56 chars]104'> != 0.6486864043382532

----------------------------------------------------------------------
Ran 1 test in 0.004s

FAILED (failures=1)
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1 回答 1

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据我所知，问题出现在重复__getitem__调用中。但以下工作：

def test_fcf_calculation(self):
    mock_fcf = MagicMock()

    mock_fcf.iloc.__getitem__.return_value = MagicMock(**{'__getitem__.side_effect': [100, 10]})

    result = avg_annual_fcf_growth_rate(mock_fcf)
    expected = ((100-10)**(1/9)) - 1
    print(mock_fcf.mock_calls)
    self.assertEqual(result, expected)
于 2018-07-30T02:44:20.393 回答