bpo-35022: unittest.mock.MagicMock now also supports __fspath__ (GH-9960)

The MagicMock class supports many magic methods, but not __fspath__. To ease
testing with modules such as os.path, this function is now supported by default.

Lib/unittest/test/testmock/testmagicmethods.py

@@ -1,5 +1,6 @@
 import math
 import unittest
+import os
 import sys
 from unittest.mock import Mock, MagicMock, _magics
 
@@ -293,6 +294,15 @@ class TestMockingMagicMethods(unittest.TestCase):
         # how to test __sizeof__ ?
 
 
+    def test_magic_methods_fspath(self):
+        mock = MagicMock()
+        expected_path = mock.__fspath__()
+        mock.reset_mock()
+
+        self.assertEqual(os.fspath(mock), expected_path)
+        mock.__fspath__.assert_called_once()
+
+
     def test_magic_methods_and_spec(self):
         class Iterable(object):
             def __iter__(self):