def METHOD_NAME(self):
    # micros are present and must be padded
    input_string = "2016-11-22T12:15:25.967Z"
    expected = "2016-11-22T12:15:25.000967Z"
    result = self._test_instance._format_micros(input_string)
    self.assertEqual(expected, result)
    # micros are present but too many digits
    input_string = "2017-08-25T18:16:16.487887736Z"
    expected = "2017-08-25T18:16:16.487887Z"
    result = self._test_instance._format_micros(input_string)
    self.assertEqual(expected, result)
    # no micros at all
    input_string = "2016-11-22T12:15:25Z"
    expected = "2016-11-22T12:15:25.000000Z"
    result = self._test_instance._format_micros(input_string)
    self.assertEqual(expected, result)
    # no micros at all n.2
    input_string = "2016-11-22T12:15:25"
    expected = "2016-11-22T12:15:25.000000Z"
    result = self._test_instance._format_micros(input_string)
    self.assertEqual(expected, result)