Backported tests for issue #18531.
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index 71aa419..19fea20 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -872,6 +872,26 @@
 
 #endif  /* ifdef HAVE_LONG_LONG */
 
+static PyObject *
+get_args(PyObject *self, PyObject *args)
+{
+    if (args == NULL) {
+        args = Py_None;
+    }
+    Py_INCREF(args);
+    return args;
+}
+
+static PyObject *
+get_kwargs(PyObject *self, PyObject *args, PyObject *kwargs)
+{
+    if (kwargs == NULL) {
+        kwargs = Py_None;
+    }
+    Py_INCREF(kwargs);
+    return kwargs;
+}
+
 /* Test tuple argument processing */
 static PyObject *
 getargs_tuple(PyObject *self, PyObject *args)
@@ -3651,6 +3671,8 @@
     {"test_pep3118_obsolete_write_locks", (PyCFunction)test_pep3118_obsolete_write_locks, METH_NOARGS},
 #endif
     {"getbuffer_with_null_view", getbuffer_with_null_view, METH_O},
+    {"get_args", get_args, METH_VARARGS},
+    {"get_kwargs", (PyCFunction)get_kwargs, METH_VARARGS|METH_KEYWORDS},
     {"getargs_tuple",           getargs_tuple,                   METH_VARARGS},
     {"getargs_keywords", (PyCFunction)getargs_keywords,
       METH_VARARGS|METH_KEYWORDS},