带有时间戳的函数的Python单元测试

Question

In a unit test for a function that outputs timestamp and say hostname on it along with other values. In the unit test if i add some timestamp and a hostname in expected output it will fail as the timestamp from the function will change every time the function is called and the hostname will change every time it is run in a different machine. What is the workaround for this? I'd appreciate your input.

output from a function:

{'datetime': '09-10-2018 23:23:23', 'hostname': 'abc.xyz.com',...}
# and it can change every time we run it

but this datetime and hostname changes depending on time, of course, and machine

expected output that i think i will use in unit test to assertEqual or assertDictEqual:

{'datetime': '09-10-2018 23:23:23', 'hostname': 'abc.xyz.com',...}

Is some other assertion check better suited for this situation?

Answer 1

You should mock the datetime.now() call, wherever it happens, so that the creation datetime is always some canned value which you can assert against during the test.

This is a common requirement, so there is some library support for it already - I can recommend freezegun :

@freeze_time("09-10-2018 23:23:23")
def test_something():
    data = something()
    assert data == {'datetime': '09-10-2018 23:23:23', 'hostname': 'abc.xyz.com',...}