Does anyone have any experience with unit testing modules that need to be tested using DateTime objects with different timezones without having a real timezone database? I am having trouble understanding how I would mock the timezone database in a way that would allow using methods such as DateTime…

Never tried what you need but I’d think that mock or patch will do the job.

I know mock, but I don’t know how to mock a timezone database with it. I don’t want to mock the functions I am calling, because I want to assert that the timezone conversions are taking place in the modules I am testing.

Intuitively, I’d say just inspect Elixir’s source and see which timezone functions it uses when a timezone database is supplied? Here’s what Elixir itself does when ultimately it gets down to calling a function from the timezone module: elixir/lib/elixir/lib/calendar/datetime.ex at 1a1eda52b46e37b0…

Just now saw your edit but it doesn’t change much. You can still make your mock respect timezone offsets. Alternatively, I think you can just use a proper timezone database and instruct it to not do network requests. tz has very configurable behaviour on when (or if?) to do automatic updates. Her…

Using past datetimes on non disputed regions should give you a rather stable timezone definition. If you still need more control then you can use Mox with the time zone database behaviour and mock that.

Elixir Programming Language Forum

Proper unit test mocking for timezone aware DateTime objects

Questions & Help Questions

hauks96 December 28, 2022, 1:00am 6

Thank you! I’ll take a look and share the results