fix(plugin): ensure mocker.stub is not detected as a coroutine function

src/pytest_mock/plugin.py

@@ -235,10 +235,10 @@ def stub(self, name: str | None = None) -> unittest.mock.MagicMock:
         :param name: the constructed stub's name as used in repr
         :return: Stub object.
         """
-        return cast(
-            unittest.mock.MagicMock,
-            self.mock_module.MagicMock(spec=lambda *args, **kwargs: None, name=name),
-        )
+        fn = lambda *args, **kwargs: None
+        stub = self.mock_module.MagicMock(spec=fn, name=name)
+        stub.__code__ = fn.__code__
+        return cast(unittest.mock.MagicMock, stub)
 
     def async_stub(self, name: str | None = None) -> AsyncMockType:
         """

tests/test_pytest_mock.py

@@ -260,6 +260,18 @@ def test_failure_message_with_name(self, mocker: MagicMock, name: str) -> None:
     def test_async_stub_type(self, mocker: MockerFixture) -> None:
         assert isinstance(mocker.async_stub(), AsyncMock)
 
+    def test_not_coroutine_function(self, mocker: MockerFixture) -> None:
+        import inspect
+
+        stub = mocker.stub()
+        assert not inspect.iscoroutinefunction(stub)
+
+    def test_async_stub_is_coroutine_function(self, mocker: MockerFixture) -> None:
+        import inspect
+
+        async_stub = mocker.async_stub()
+        assert inspect.iscoroutinefunction(async_stub)
+
 
 def test_instance_method_spy(mocker: MockerFixture) -> None:
     class Foo: