bpo-41403: Improve error message for invalid mock target

Author: iritkatriel

Lib/unittest/mock.py

@@ -1589,7 +1589,7 @@ def stop(self):
 def _get_target(target):
     try:
         target, attribute = target.rsplit('.', 1)
-    except (TypeError, ValueError):
+    except (TypeError, ValueError, AttributeError):
         raise TypeError("Need a valid target to patch. You supplied: %r" %
                         (target,))
     return partial(pkgutil.resolve_name, target), attribute

Lib/unittest/test/testmock/testpatch.py

@@ -1933,8 +1933,13 @@ def test(mock):
 
 
     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):