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python - Python 3.x 中的单元测试“pathlib.Path.is_file”

问题描述

我是 Python 单元测试的新手，在运行测试时遇到了问题。我想实现如下所示的测试类：https ://www.toptal.com/python/an-introduction-to-mocking-in-python ，但稍作修改。而不是使用os.path.isfile我想使用pathlib.Path.is_file.

这是要测试的实际类：

import os

from pathlib import Path

class FileUtils:

    @staticmethod
    def isFile(file):
        return Path(file).is_file()

    @staticmethod
    def deleteFile(file):
        if FileUtils.isFile(file):
            os.remove(file)

这是测试类：

import mock, unittest

class FileUtilsTest(unittest.TestCase):

    testFilename = "filename"

    @mock.patch('FileUtils.Path')
    @mock.patch('FileUtils.os')
    def testDeleteFiles(self, osMock, pathMock):

        pathMock.is_file.return_value = False
        FileUtils.deleteFile(self.testFilename)
        self.assertFalse(osMock.remove.called, 'Failed to not remove the file if not present.')

        pathMock.is_file.return_value = True
        FileUtils.deleteFile(self.testFilename)
        osMock.remove.assert_called_with(self.testFilename)

这将导致以下错误消息：

Finding files... done.
Importing test modules ... done.

======================================================================
FAIL: testDeleteFile (FileUtilsTest.FileUtilsTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "...\AppData\Local\Continuum\anaconda3\lib\site-packages\mock\mock.py", line 1305, in patched
    return func(*args, **keywargs)
  File "...\FileUtilsTest.py", line 13, in testDeleteFile
    self.assertFalse(osMock.remove.called, 'Failed to not remove the file if not present.')
AssertionError: True is not false : Failed to not remove the file if not present.

----------------------------------------------------------------------
Ran 1 test in 0.003s

FAILED (failures=1)

如何FileUtils.deleteFile使用@mock.patch装饰器测试该方法？

标签： pythonpython-3.xunit-testingmocking

解决方案

这里的问题是，当您修补Path模块中的符号时，您正在替换Path. 但is_file不是构造函数的属性 - 它是构造函数返回的对象的属性。构造函数被调用，你调用is_file返回值。所以你也需要模拟那部分。为此，请在Path调用符号时设置要返回的模拟。

import mock, unittest

class FileUtilsTest(unittest.TestCase):

    testFilename = "filename"

    @mock.patch('FileUtils.Path')
    @mock.patch('FileUtils.os')
    def testDeleteFiles(self, osMock, pathMock):
        mock_path = MagicMock()
        pathMock.return_value = mock_path

        mock_path.is_file.return_value = False
        FileUtils.deleteFile(self.testFilename)
        self.assertFalse(osMock.remove.called, 'Failed to not remove the file if not present.')

        mock_path.is_file.return_value = True
        FileUtils.deleteFile(self.testFilename)
        osMock.remove.assert_called_with(self.testFilename)

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