我创建了一个函数,该函数返回距离下次出现该时间还剩下的秒数,但我在为其编写单元测试时遇到了问题。人们如何测试这种类型的调用函数datetime.now()
in it?
添加另一个参数(current_time
)仅仅测试它似乎是错误的,因为它改变了函数的初始要求。
要测试的功能是。
from datetime import datetime, time, timedelta
def get_time_left(target_time):
'''return float of number of seconds left until the target_time'''
if not isinstance( target_time, time ):
raise TypeError("target_time must be datetime.time")
curr_time = datetime.now()
target_datetime = datetime.combine( datetime.today(), target_time )
if curr_time > target_datetime:
target_datetime = curr_time + timedelta(1)
seconds_left = (curr_time - target_datetime).total_seconds()
return seconds_left
对它的测试是。
class TestDTime(unittest.TestCase):
def test_time_left(self):
dt_now = datetime.now()
tm_5sec_future = ( dt_now + timedelta(0,5) ).time()
self.assertEqual( dtime.get_time_left(tm_5sec_future), 5.0)
结果是。
======================================================================
FAIL: test_time_left (__main__.TestDTime)
----------------------------------------------------------------------
Traceback (most recent call last):
File "tests/ctatest.py", line 37, in test_time_left
self.assertEqual( dtime.get_time_left(tm_5sec_future), 5.0)
AssertionError: -4.999985 != 5.0
在不向函数添加任何参数的情况下进行单元测试的最佳方法是什么?