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

Question

我是 Python 单元测试新手，在运行测试时遇到问题。我想实现以下测试类，如下所示:https://www.toptal.com/python/an-introduction-to-mocking-in-python ，但稍微修改的。我想使用 pathlib.Path.is_file，而不是使用 os.path.isfile。

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)

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

Answer 1

这里的问题是，当您修补模块中的符号 Path 时，您正在替换 Path 构造函数的符号。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。调用构造函数，然后对返回值调用 is_file。所以你也需要模拟那部分。为此，请设置在调用 Path 符号时返回的模拟。

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)