gh-117398: Add datetime C-API type check test for subinterpreters (gh-119604)

Check if the DateTime C-API type matches the datetime.date type on main and shared/isolated subinterpreters.

Lib/test/datetimetester.py

@@ -13,6 +13,7 @@ import random
 import re
 import struct
 import sys
+import textwrap
 import unittest
 import warnings
 
@@ -38,6 +39,10 @@ try:
     import _testcapi
 except ImportError:
     _testcapi = None
+try:
+    import _interpreters
+except ModuleNotFoundError:
+    _interpreters = None
 
 # Needed by test_datetime
 import _strptime
@@ -6780,6 +6785,42 @@ class CapiTest(unittest.TestCase):
 
                     self.assertEqual(dt_orig, dt_rt)
 
+    def test_type_check_in_subinterp(self):
+        script = textwrap.dedent(f"""
+            if {_interpreters is None}:
+                import _testcapi as module
+                module.test_datetime_capi()
+            else:
+                import importlib.machinery
+                import importlib.util
+                fullname = '_testcapi_datetime'
+                origin = importlib.util.find_spec('_testcapi').origin
+                loader = importlib.machinery.ExtensionFileLoader(fullname, origin)
+                spec = importlib.util.spec_from_loader(fullname, loader)
+                module = importlib.util.module_from_spec(spec)
+                spec.loader.exec_module(module)
+
+            def run(type_checker, obj):
+                if not type_checker(obj, True):
+                    raise TypeError(f'{{type(obj)}} is not C API type')
+
+            import _datetime
+            run(module.datetime_check_date,     _datetime.date.today())
+            run(module.datetime_check_datetime, _datetime.datetime.now())
+            run(module.datetime_check_time,     _datetime.time(12, 30))
+            run(module.datetime_check_delta,    _datetime.timedelta(1))
+            run(module.datetime_check_tzinfo,   _datetime.tzinfo())
+        """)
+        if _interpreters is None:
+            ret = support.run_in_subinterp(script)
+            self.assertEqual(ret, 0)
+        else:
+            for name in ('isolated', 'legacy'):
+                with self.subTest(name):
+                    config = _interpreters.new_config(name).__dict__
+                    ret = support.run_in_subinterp_with_config(script, **config)
+                    self.assertEqual(ret, 0)
+
 
 def load_tests(loader, standard_tests, pattern):
     standard_tests.addTest(ZoneInfoCompleteTest())