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

Backports: a875ea58b29fbf510f9790ae1653eeaa47dc0de8
Signed-off-by: Chris Withers <chris@withers.org>

Needed some munging due to package layout and code differences.

2 files changed, 18 insertions, 0 deletions

diff --git a/mock/tests/support.py b/mock/tests/support.py
index 2bbc8a2..933be92 100644
--- a/mock/tests/support.py
+++ b/mock/tests/support.py
@@ -2,6 +2,9 @@ import contextlib
 import sys
 
 
+target = {'foo': 'FOO'}
+
+
 def is_instance(obj, klass):
     """Version of is_instance that doesn't access __class__"""
     return issubclass(type(obj), klass)
diff --git a/mock/tests/testpatch.py b/mock/tests/testpatch.py
index 434e780..d8857b9 100644
--- a/mock/tests/testpatch.py
+++ b/mock/tests/testpatch.py
@@ -668,6 +668,21 @@ 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('mock.tests.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
+
+
     @unittest.expectedFailure
     def test_patch_descriptor(self):
         # would be some effort to fix this - we could special case the