test_tslib.py 文件源码

def test_addition_subtraction_preserve_frequency(self):
        timestamp_instance = date_range('2014-03-05', periods=1, freq='D')[0]
        timedelta_instance = datetime.timedelta(days=1)
        original_freq = timestamp_instance.freq
        self.assertEqual((timestamp_instance + 1).freq, original_freq)
        self.assertEqual((timestamp_instance - 1).freq, original_freq)
        self.assertEqual(
            (timestamp_instance + timedelta_instance).freq, original_freq)
        self.assertEqual(
            (timestamp_instance - timedelta_instance).freq, original_freq)

        timedelta64_instance = np.timedelta64(1, 'D')
        self.assertEqual(
            (timestamp_instance + timedelta64_instance).freq, original_freq)
        self.assertEqual(
            (timestamp_instance - timedelta64_instance).freq, original_freq)