Add tests for wrapped metaclass __call__

Author: serhiy-storchaka

Lib/test/test_inspect/test_inspect.py

@@ -4042,6 +4042,79 @@ def __init__(self, b):
                            ('bar', 2, ..., "keyword_only")),
                           ...))
 
+    def test_signature_on_class_with_wrapped_metaclass_call(self):
+        class CM(type):
+            @identity
+            def __call__(cls, a):
+                pass
+        class C(metaclass=CM):
+            def __init__(self, b):
+                pass
+
+        self.assertEqual(self.signature(C),
+                         ((('a', ..., ..., "positional_or_keyword"),),
+                          ...))
+
+        with self.subTest('classmethod'):
+            class CM(type):
+                @classmethod
+                @identity
+                def __call__(cls, a):
+                    return a
+            class C(metaclass=CM):
+                def __init__(self, b):
+                    pass
+
+            self.assertEqual(C(1), 1)
+            self.assertEqual(self.signature(C),
+                            ((('a', ..., ..., "positional_or_keyword"),),
+                            ...))
+
+        with self.subTest('staticmethod'):
+            class CM(type):
+                @staticmethod
+                @identity
+                def __call__(a):
+                    return a
+            class C(metaclass=CM):
+                def __init__(self, b):
+                    pass
+
+            self.assertEqual(C(1), 1)
+            self.assertEqual(self.signature(C),
+                            ((('a', ..., ..., "positional_or_keyword"),),
+                            ...))
+
+        with self.subTest('MethodType'):
+            class A:
+                @identity
+                def call(self, a):
+                    return a
+            class CM(type):
+                __call__ = A().call
+            class C(metaclass=CM):
+                def __init__(self, b):
+                    pass
+
+            self.assertEqual(C(1), 1)
+            self.assertEqual(self.signature(C),
+                            ((('a', ..., ..., "positional_or_keyword"),),
+                            ...))
+
+        with self.subTest('descriptor'):
+            class CM(type):
+                @DescWithDeco
+                def __call__(self, a):
+                    return a
+            class C(metaclass=CM):
+                def __init__(self, b):
+                    pass
+
+            self.assertEqual(C(1), 1)
+            self.assertEqual(self.signature(C),
+                            ((('a', ..., ..., "positional_or_keyword"),),
+                            ...))
+
     def test_signature_on_class_with_decorated_init(self):
         class C:
             @identity