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.

Backports: 6c83d9f4a72905d968418bef670bb3091d2744db
Signed-off-by: Chris Withers <chris@simplistix.co.uk>

Needed some re-working as this can only work and apply on Python 3

3 files changed, 16 insertions, 1 deletions

diff --git a/NEWS.d/2018-10-18-17-57-28.bpo-35022.KeEF4T.rst b/NEWS.d/2018-10-18-17-57-28.bpo-35022.KeEF4T.rst
new file mode 100644
index 0000000..426be70
--- /dev/null
+++ b/NEWS.d/2018-10-18-17-57-28.bpo-35022.KeEF4T.rst
@@ -0,0 +1,2 @@
+:class:`unittest.mock.MagicMock` now supports the ``__fspath__`` method
+(from :class:`os.PathLike`).
diff --git a/mock/mock.py b/mock/mock.py
index a414f3a..6e790f1 100644
--- a/mock/mock.py
+++ b/mock/mock.py
@@ -1864,7 +1864,7 @@ inplace = ' '.join('i%s' % n for n in numerics.split())
 right = ' '.join('r%s' % n for n in numerics.split())
 extra = ''
 if six.PY3:
-    extra = 'bool next '
+    extra = 'bool next fspath '
 else:
     extra = 'unicode long nonzero oct hex truediv rtruediv '
 
@@ -1909,6 +1909,7 @@ _calculate_return_value = {
     '__str__': lambda self: object.__str__(self),
     '__sizeof__': lambda self: object.__sizeof__(self),
     '__unicode__': lambda self: unicode(object.__str__(self)),
+    '__fspath__': lambda self: type(self).__name__+'/'+self._extract_mock_name()+'/'+str(id(self)),
 }
 
 _return_values = {
diff --git a/mock/tests/testmagicmethods.py b/mock/tests/testmagicmethods.py
index 1056b2a..705b9d1 100644
--- a/mock/tests/testmagicmethods.py
+++ b/mock/tests/testmagicmethods.py
@@ -12,6 +12,7 @@ except NameError:
     long = int
 
 import math
+import os
 import sys
 import textwrap
 import unittest
@@ -361,6 +362,17 @@ class TestMockingMagicMethods(unittest.TestCase):
         self.assertEqual(mock, object())
 
 
+    def test_magic_methods_fspath(self):
+        mock = MagicMock()
+        if six.PY2:
+            self.assertRaises(AttributeError, lambda: mock.__fspath__)
+        else:
+            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):