bpo-41403: Improve error message for invalid mock target (GH-30833)

3 files changed, 13 insertions, 5 deletions

diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index 9f99a5a..9137501 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -1589,9 +1589,9 @@ class _patch(object):
 def _get_target(target):
     try:
         target, attribute = target.rsplit('.', 1)
-    except (TypeError, ValueError):
-        raise TypeError("Need a valid target to patch. You supplied: %r" %
-                        (target,))
+    except (TypeError, ValueError, AttributeError):
+        raise TypeError(
+            f"Need a valid target to patch. You supplied: {target!r}")
     return partial(pkgutil.resolve_name, target), attribute
 
 
diff --git a/Lib/unittest/test/testmock/testpatch.py b/Lib/unittest/test/testmock/testpatch.py
index 233a5af..8ab63a1 100644
--- a/Lib/unittest/test/testmock/testpatch.py
+++ b/Lib/unittest/test/testmock/testpatch.py
@@ -1933,8 +1933,13 @@ class PatchTest(unittest.TestCase):
 
 
     def test_invalid_target(self):
-        with self.assertRaises(TypeError):
-            patch('')
+        class Foo:
+            pass
+
+        for target in ['', 12, Foo()]:
+            with self.subTest(target=target):
+                with self.assertRaises(TypeError):
+                    patch(target)
 
 
     def test_cant_set_kwargs_when_passing_a_mock(self):
diff --git a/Misc/NEWS.d/next/Library/2022-01-23-18-04-45.bpo-41403.SgoHqV.rst b/Misc/NEWS.d/next/Library/2022-01-23-18-04-45.bpo-41403.SgoHqV.rst
new file mode 100644
index 0000000..ede159b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-01-23-18-04-45.bpo-41403.SgoHqV.rst
@@ -0,0 +1,3 @@
+Make :meth:`mock.patch` raise a :exc:`TypeError` with a relevant error
+message on invalid arg. Previously it allowed a cryptic
+:exc:`AttributeError` to escape.