From 01d94ca1533e0af74792a199e50783f69e7bad64 Mon Sep 17 00:00:00 2001
From: Nikita Sobolev <mail@sobolevn.me>
Date: Sat, 7 Jan 2023 13:49:15 +0300
Subject: [PATCH] gh-96127: Fix `inspect.signature` call on mocks (#96335)

(cherry picked from commit 9e7d7266ecdcccc02385fe4ccb094f3444102e26)
---
 Lib/test/test_inspect.py                      | 19 +++++++++++++++++++
 Lib/unittest/mock.py                          | 10 +++++++++-
 ...2-08-27-10-35-50.gh-issue-96127.8RdLre.rst |  2 ++
 3 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 Misc/NEWS.d/next/Library/2022-08-27-10-35-50.gh-issue-96127.8RdLre.rst

diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py
index 9ea49854cbc636..c50486003a4dab 100644
--- a/Lib/test/test_inspect.py
+++ b/Lib/test/test_inspect.py
@@ -3238,6 +3238,25 @@ def test_signature_on_lambdas(self):
                          ((('a', 10, ..., "positional_or_keyword"),),
                           ...))
 
+    def test_signature_on_mocks(self):
+        # https://github.com/python/cpython/issues/96127
+        for mock in (
+            unittest.mock.Mock(),
+            unittest.mock.AsyncMock(),
+            unittest.mock.MagicMock(),
+        ):
+            with self.subTest(mock=mock):
+                self.assertEqual(str(inspect.signature(mock)), '(*args, **kwargs)')
+
+    def test_signature_on_noncallable_mocks(self):
+        for mock in (
+            unittest.mock.NonCallableMock(),
+            unittest.mock.NonCallableMagicMock(),
+        ):
+            with self.subTest(mock=mock):
+                with self.assertRaises(TypeError):
+                    inspect.signature(mock)
+
     def test_signature_equality(self):
         def foo(a, *, b:int) -> float: pass
         self.assertFalse(inspect.signature(foo) == 42)
diff --git a/Lib/unittest/mock.py b/Lib/unittest/mock.py
index fa0bd9131a21e7..54bd3ecdd76f14 100644
--- a/Lib/unittest/mock.py
+++ b/Lib/unittest/mock.py
@@ -2201,7 +2201,15 @@ def __init__(self, /, *args, **kwargs):
         self.__dict__['_mock_await_args'] = None
         self.__dict__['_mock_await_args_list'] = _CallList()
         code_mock = NonCallableMock(spec_set=CodeType)
-        code_mock.co_flags = inspect.CO_COROUTINE
+        code_mock.co_flags = (
+            inspect.CO_COROUTINE
+            + inspect.CO_VARARGS
+            + inspect.CO_VARKEYWORDS
+        )
+        code_mock.co_argcount = 0
+        code_mock.co_varnames = ('args', 'kwargs')
+        code_mock.co_posonlyargcount = 0
+        code_mock.co_kwonlyargcount = 0
         self.__dict__['__code__'] = code_mock
         self.__dict__['__name__'] = 'AsyncMock'
         self.__dict__['__defaults__'] = tuple()
diff --git a/Misc/NEWS.d/next/Library/2022-08-27-10-35-50.gh-issue-96127.8RdLre.rst b/Misc/NEWS.d/next/Library/2022-08-27-10-35-50.gh-issue-96127.8RdLre.rst
new file mode 100644
index 00000000000000..79edd8fd5d8f40
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-08-27-10-35-50.gh-issue-96127.8RdLre.rst
@@ -0,0 +1,2 @@
+``inspect.signature`` was raising ``TypeError`` on call with mock objects.
+Now it correctly returns ``(*args, **kwargs)`` as infered signature.