From: Robert Collins <robert.collins@cognite.com>
Date: Tue, 11 Jun 2024 05:41:12 +0000 (+0200)
Subject: gh-119600: mock: do not access attributes of original when new_callable is set (... 
X-Git-Tag: v3.14.0a1~1543
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=422c4fc855afd18bcc6415902ea1d85a50cb7ce1;p=thirdparty%2FPython%2Fcpython.git

gh-119600: mock: do not access attributes of original when new_callable is set (#119601)

In order to patch flask.g e.g. as in #84982, that
proxies getattr must not be invoked. For that,
mock must not try to read from the original
object. In some cases that is unavoidable, e.g.
when doing autospec. However, patch("flask.g",
new_callable=MagicMock) should be entirely safe.
---

diff --git a/Lib/test/test_unittest/testmock/support.py b/Lib/test/test_unittest/testmock/support.py
index 49986d65dc47..6c535b7944f2 100644
--- a/Lib/test/test_unittest/testmock/support.py
+++ b/Lib/test/test_unittest/testmock/support.py
@@ -14,3 +14,14 @@ class SomeClass(object):
 
 class X(object):
     pass
+
+# A standin for weurkzeug.local.LocalProxy - issue 119600
+def _inaccessible(*args, **kwargs):
+    raise AttributeError
+
+
+class OpaqueProxy:
+    __getattribute__ = _inaccessible
+
+
+g = OpaqueProxy()
diff --git a/Lib/test/test_unittest/testmock/testpatch.py b/Lib/test/test_unittest/testmock/testpatch.py
index be75fda7826a..f26e74ce0bc1 100644
--- a/Lib/test/test_unittest/testmock/testpatch.py
+++ b/Lib/test/test_unittest/testmock/testpatch.py
@@ -2045,6 +2045,13 @@ class PatchTest(unittest.TestCase):
         with self.assertRaises(TypeError):
             test()
 
+    def test_patch_proxy_object(self):
+        @patch("test.test_unittest.testmock.support.g", new_callable=MagicMock())
+        def test(_):
+            pass
+
+        test()
+
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index 3ef83e263f53..edabb4520c13 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -1508,13 +1508,12 @@ class _patch(object):
                 if isinstance(original, type):
                     # If we're patching out a class and there is a spec
                     inherit = True
-            if spec is None and _is_async_obj(original):
-                Klass = AsyncMock
-            else:
-                Klass = MagicMock
-            _kwargs = {}
+
+            # Determine the Klass to use
             if new_callable is not None:
                 Klass = new_callable
+            elif spec is None and _is_async_obj(original):
+                Klass = AsyncMock
             elif spec is not None or spec_set is not None:
                 this_spec = spec
                 if spec_set is not None:
@@ -1527,7 +1526,12 @@ class _patch(object):
                     Klass = AsyncMock
                 elif not_callable:
                     Klass = NonCallableMagicMock
+                else:
+                    Klass = MagicMock
+            else:
+                Klass = MagicMock
 
+            _kwargs = {}
             if spec is not None:
                 _kwargs['spec'] = spec
             if spec_set is not None:
diff --git a/Misc/NEWS.d/next/Library/2024-06-10-14-00-40.gh-issue-119600.jJMf4C.rst b/Misc/NEWS.d/next/Library/2024-06-10-14-00-40.gh-issue-119600.jJMf4C.rst
new file mode 100644
index 000000000000..04c9ca9c3fd7
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-06-10-14-00-40.gh-issue-119600.jJMf4C.rst
@@ -0,0 +1,2 @@
+Fix :func:`unittest.mock.patch` to not read attributes of the target when
+``new_callable`` is set. Patch by Robert Collins.