how to use freezegun on logbook

Question

I'm trying to run tests that involve mocking datetime within logbook (for logic around logbook.TimedRotatingFileHandler). But freezegun doesn't reach logbook. Logs print as the current (un-mocked, correct) current time!

my example prints the confusing message

[2019-07-09 22:01:21.583288] INFO: None: test time: 2000-01-01 00:01:00

for the following pytest

from freezegun import freeze_time
import logbook
import sys
import datetime as dt

def test_logbook():
    faketime = freeze_time('2000-01-01 00:01')
    faketime.start()
    assert dt.datetime.now().strftime('%Y%d%m') == '20000101'
    log = logbook.Logger()
    log.handlers.append(logbook.StreamHandler(sys.stdout))
    log.info('test time: ' + str(dt.datetime.now()))
    faketime.stop()
    assert 0

Answer 1

You are freezing time after the import of logbook, not covering some init on module level. Move the import inside the scope with time frozen; example:

from freezegun import freeze_time
import sys
import datetime as dt

def test_logbook(capsys):
    with freeze_time('2000-01-01 00:01'):
        import logbook
        assert dt.datetime.now().strftime('%Y%d%m') == '20000101'
        log = logbook.Logger()
        log.handlers.append(logbook.StreamHandler(sys.stdout))
        log.info('hello world')
    assert capsys.readouterr().out == '[2000-01-01 00:01:00.000000] INFO: None: hello world\n'