bpo-35512: Resolve string target to patch.dict decorator during function call GH#12000

* Resolve string target to patch.dict during function call

* Add NEWS entry

* Remove unneeded call

* Restore original value for support.target and refactor assertions

* Add extra assertion to verify unpatched dict

1 files changed, 17 insertions, 0 deletions

diff --git a/Lib/unittest/test/testmock/testpatch.py b/Lib/unittest/test/testmock/testpatch.py
index f05225730d..c484adb605 100644
--- a/Lib/unittest/test/testmock/testpatch.py
+++ b/Lib/unittest/test/testmock/testpatch.py
@@ -664,6 +664,23 @@ class PatchTest(unittest.TestCase):
         test()
 
 
+    def test_patch_dict_decorator_resolution(self):
+        # bpo-35512: Ensure that patch with a string target resolves to
+        # the new dictionary during function call
+        original = support.target.copy()
+
+        @patch.dict('unittest.test.testmock.support.target', {'bar': 'BAR'})
+        def test():
+            self.assertEqual(support.target, {'foo': 'BAZ', 'bar': 'BAR'})
+
+        try:
+            support.target = {'foo': 'BAZ'}
+            test()
+            self.assertEqual(support.target, {'foo': 'BAZ'})
+        finally:
+            support.target = original
+
+
     def test_patch_descriptor(self):
         # would be some effort to fix this - we could special case the
         # builtin descriptors: classmethod, property, staticmethod