# Testing in different Time Zones <span class="related-pages">#testing/automated-testing #testing/manual-testing</span> ## Fixing the time zone to UTC in Jest Currently, our Jest tests fix the time zone at run-time to `UTC` in [tests/global-setup.js](https://github.com/obsidian-tasks-group/obsidian-tasks/blob/main/tests/global-setup.js). This was done to ensure that the tests pass for contributors all around the world, regardless of their own time zone. ## Why we don't use 'moment-timezone' ... in `src/`: 1. Obsidian plugins are instructed to use `moment` as supplied by Obsidian, to reduce plugin size. 1. `moment-timezone` increases the Tasks plugin `main.js` size 10-fold, which would slow down start-up time. 1. So we can't use `moment-timezone` in the released plugin. ... in `tests/`: 1. The only way to set the timezone dynamically in tests is to use [moment-timezone](https://momentjs.com/timezone/docs/). 1. But `moment-timezone` modifies the behaviour of `moment` 1. Which would invalidate any of tests of behaviour that uses `moment`: we could not be confident that the code would behave the same in the released plugin as it does in tests. ## Manually testing in different time zones In the absence of automated testing of Tasks in different time zones, see this manual test in the 'Tasks-Demo' vault: - [Tasks-Demo/Manual Testing/Time Zones/Pacific-Auckland.md](https://github.com/obsidian-tasks-group/obsidian-tasks/blob/main/resources/sample_vaults/Tasks-Demo/Manual%20Testing/Time%20Zones/Pacific-Auckland.md).