[bauble]

I had a unit tests for a Java LocalDate that was being increased by one year. It checked whether the month and day were the same, and failed because the current day (29) didn't equal the year-hence one (28). I changed it to check that the difference between the days was less than two.

[nathanwh]

Previously your unit test was broken one day every four ish years. Now it's broken every day :)

[bspammer]

A unit test shouldn’t even be depending on the current date in the first place

[yen223]

This is a hard-earned lesson, but it's true.

Instead of doing

  def do_something_with_date():
      now = datetime.now()
      return now - timedelta(days=2)

you should do

  def do_something_with_date(now):
      return now - timedelta(days=2)

and explicitly pass in edge-case dates into the `now` param in your unit tests.

Alternatively, if you're using Python, use the freezegun library to fix the current time in tests: https://github.com/spulec/freezegun

[dimaaan]

Right, fixed such test today