我有以下类和方法:
class DateTimeHelper(object):
@staticmethod
def get_utc_millisecond_timestamp():
(dt, micro) = datetime.datetime.utcnow().strftime('%Y-%m-%d %H:%M:%S.%f').split('.')
return "%s.%03d" % (dt, int(micro) / 1000) # UTC time with millisecond
如何对它进行单元测试?尽管这很简单,但我完全被难住了。这是我的第一个单元测试。
最佳答案
使用 unittest.mock
library(Python 3.3 及更新版本,向后移植为 mock
),替换对被测代码外部的任何代码的调用。
在这里,我不仅要模拟 utcnow()
,还要模拟 strftime()
,只返回一个字符串对象:
with mock.patch('datetime.datetime') as dt_mock:
dt_mock.utcnow.return_value.strftime.return_value = '2016-08-04 12:22:44.123456'
result = DateTimeHelper.get_utc_millisecond_timestamp()
如果您觉得测试 strftime()
参数很重要,请给 dt_mock.utcnow.return_value
一个明确的 datetime
对象来返回;但是,您必须在模拟之前 创建该测试对象,因为您不能只模拟datetime.datetime.utcnow
类方法:
testdt = datetime.datetime(2016, 8, 4, 12, 22, 44, 123456)
with mock.patch('datetime.datetime') as dt_mock:
dt_mock.utcnow.return_value = testdt
result = DateTimeHelper.get_utc_millisecond_timestamp()
或者,在您的单元测试中,使用 from datetime import datetime
来保留对未模拟的类的引用。
演示:
>>> from unittest import mock
>>> import datetime
>>> class DateTimeHelper(object):
... @staticmethod
... def get_utc_millisecond_timestamp():
... (dt, micro) = datetime.datetime.utcnow().strftime('%Y-%m-%d %H:%M:%S.%f').split('.')
... return "%s.%03d" % (dt, int(micro) / 1000) # UTC time with millisecond
...
>>> with mock.patch('datetime.datetime') as dt_mock:
... dt_mock.utcnow.return_value.strftime.return_value = '2016-08-04 12:22:44.123456'
... result = DateTimeHelper.get_utc_millisecond_timestamp()
...
>>> result
'2016-08-04 12:22:44.123'
>>> testdt = datetime.datetime(2016, 8, 4, 12, 22, 44, 123456)
>>> with mock.patch('datetime.datetime') as dt_mock:
... dt_mock.utcnow.return_value = testdt
... result = DateTimeHelper.get_utc_millisecond_timestamp()
...
>>> result
'2016-08-04 12:22:44.123'
关于python - 如何使用日期时间对方法进行单元测试?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/39252328/