Some test refactoring and improvements.

Author: ZeroIntensity

Lib/test/datetimetester.py

@@ -3652,7 +3652,7 @@ def test_repr_subclass(self):
         self.assertEqual(repr(td), "SubclassDatetime(2010, 10, 2, 0, 0, 3)")
 
     @support.cpython_only
-    def test_concurrent_initialization(self):
+    def test_concurrent_initialization_subinterpreter(self):
         # Run in a subprocess to ensure we get a clean version of _datetime
         script = """if True:
         from concurrent.futures import InterpreterPoolExecutor
@@ -3670,6 +3670,13 @@ def func():
         self.assertEqual(out, b"a" * 8)
         self.assertEqual(err, b"")
 
+        # Now test against concurrent reinitialization
+        script += "\nimport _datetime"
+        rc, out, err = script_helper.assert_python_ok("-c", script)
+        self.assertEqual(rc, 0)
+        self.assertEqual(out, b"a" * 8)
+        self.assertEqual(err, b"")
+
 
 class TestSubclassDateTime(TestDateTime):
     theclass = SubclassDatetime