Remove unit test that offers little value to fix Python 3.6 compatibility.

Author: johnthagen

test.py

@@ -136,17 +136,5 @@ def test_single(self):  # type: () -> None
         self.assertEqual(error_element.get('message'), '4: error message')
 
 
-class ParseArgumentsTestCase(unittest.TestCase):
-    def test_no_arguments(self):  # type: () -> None
-        with self.assertRaises(SystemExit):
-            # Suppress argparse stderr.
-            class NullWriter:
-                def write(self, s):  # type: (str) -> None
-                    pass
-
-            sys.stderr = NullWriter()
-            parse_arguments()
-
-
 if __name__ == '__main__':
     unittest.main()