Add tests to functools.wraps (#12173)

These tests demonstrate the issue described in #10653.

Author: srittau

stdlib/@tests/test_cases/check_functools.py

@@ -23,6 +23,37 @@ def wrapper(*args: P.args, **kwargs: P.kwargs) -> T_co:
     return wrapper
 
 
+def check_wraps_function() -> None:
+    def wrapped(x: int) -> None: ...
+    @wraps(wrapped)
+    def identical_wrapper(x: int) -> None: ...
+    @wraps(wrapped)
+    def other_signature_wrapper(x: str, y: float) -> None: ...
+
+    identical_wrapper(3)
+    other_signature_wrapper("parrot", 42.0)
+
+
+def check_wraps_method() -> None:
+    class Wrapped:
+        def wrapped(self, x: int) -> None: ...
+        @wraps(wrapped)
+        def wrapper(self, x: int) -> None: ...
+
+    class Wrapper:  # pyright: ignore[reportUnusedClass]
+        @wraps(Wrapped.wrapped)
+        def method(self, x: int) -> None: ...
+
+    @wraps(Wrapped.wrapped)
+    def func_wrapper(x: int) -> None: ...
+
+    # TODO: The following should work, but currently don't.
+    # https://github.com/python/typeshed/issues/10653
+    # Wrapped().wrapper(3)
+    # Wrapper().method(3)
+    func_wrapper(3)
+
+
 class A:
     def __init__(self, x: int):
         self.x = x