Add a test for pending calls.

Author: ZeroIntensity

Lib/test/test_capi/test_misc.py

@@ -22,6 +22,7 @@
 from test import support
 from test.support import MISSING_C_DOCSTRINGS
 from test.support import import_helper
+from test.support import script_helper
 from test.support import threading_helper
 from test.support import warnings_helper
 from test.support import requires_limited_api
@@ -1641,6 +1642,36 @@ def subthread():
 
             self.assertEqual(actual, int(interpid))
 
+    @threading_helper.requires_working_threading()
+    def test_pending_call_creates_thread(self):
+        source = """
+        import _testcapi
+        import threading
+        import time
+
+
+        def output():
+            print(24)
+            time.sleep(1)
+            print(42)
+
+
+        def callback():
+            threading.Thread(target=output).start()
+
+
+        def create_pending_call():
+            time.sleep(1)
+            _testcapi.simple_pending_call(callback)
+
+
+        threading.Thread(target=create_pending_call).start()
+        """
+        return_code, stdout, stderr = script_helper.assert_python_ok('-c', textwrap.dedent(source))
+        self.assertEqual(return_code, 0)
+        self.assertEqual(stdout, b"24\n42\n")
+        self.assertEqual(stderr, b"")
+
 
 class SubinterpreterTest(unittest.TestCase):
 

Modules/_testcapimodule.c

@@ -2546,6 +2546,16 @@ toggle_reftrace_printer(PyObject *ob, PyObject *arg)
     Py_RETURN_NONE;
 }
 
+static PyObject *
+simple_pending_call(PyObject *self, PyObject *callable)
+{
+    if (Py_AddPendingCall(_pending_callback, Py_NewRef(callable)) < 0) {
+        return NULL;
+    }
+
+    Py_RETURN_NONE;
+}
+
 static PyMethodDef TestMethods[] = {
     {"set_errno",               set_errno,                       METH_VARARGS},
     {"test_config",             test_config,                     METH_NOARGS},
@@ -2640,6 +2650,7 @@ static PyMethodDef TestMethods[] = {
     {"test_atexit", test_atexit, METH_NOARGS},
     {"code_offset_to_line", _PyCFunction_CAST(code_offset_to_line), METH_FASTCALL},
     {"toggle_reftrace_printer", toggle_reftrace_printer, METH_O},
+    {"simple_pending_call", simple_pending_call, METH_O},
     {NULL, NULL} /* sentinel */
 };