Update label displaying next backup time.

[real-yfprojects]

Always update the label in the schedule tab that displays the next time to start a backup when the scheduler updates its timer.
Fixes #1116.

• src/vorta/scheduler.py (VortaScheduler): Add schedule_changed signal.

• src/vorta/scheduler.py (VortaScheduler.set_timer_for_profile): Emit schedule_changed signal.

• src/vorta/views/schedule_tab.py (ScheduleTab): Connect draw_next_scheduled_backup to schedule_changed signal.

[real-yfprojects]

I was able to track the error down:

When VortaApp is initialized it creates a main window which in turn creates a ScheduleTab connecting to the scheduler. In the tests (conftest.init_db) the main window is deleted while the schedule tab is not while remaining connected to the signal. This instance will then produce the error seen because it isn't able to access its parent window.

This is clearly an issue with the testing setup or maybe with VortaApp creating the main window. Could you have a look at the configuration of the test and try to fix this, @m3nu?

[m3nu]

Redoing all the tests sounds like a big task just to preview the next scheduler run more often.

I keep the app around, but reset the database and windows during tests. Destroying the whole app would take much longer and caused segfaults from Qt, as it expects only one Qt app per process. 😬

[real-yfprojects]

I implemented a work-around for the failing test.

[m3nu]

That's a clever implementation and good workaround for the test. Did something like this myself in a few places. Good job!

Let me run this locally for a while and then merge. Thanks!

[real-yfprojects]

Do you know that you don't have to merge the master into the feature branch if you merge it into master afterwards? In case you want to check the tests you can also rebase the branch from within the github ui or using git rebase master. That won't add a new commit to the history.

[m3nu]

Works as promised. Very elegant solution. Thanks for taking care! 💃