Initialize empty schedules when calling .in_schedule if they do not already exist

[SET001]

Objective

Fixes #7910

Solution

create shedule if it does not exist by the time add_system called

My first PR. Not sure how much this solution feet here but at least it seems to work. Any comment is appreciated.

[github-actions]

Welcome, new contributor!

Please make sure you've read our contributing guide and we look forward to reviewing your pull request shortly ✨

[alice-i-cecile]

create set if it does not exist by the time add_system called

This is not correct; you're creating a Schedule :)

[SET001]

create set if it does not exist by the time add_system called

This is not correct; you're creating a Schedule :)

My mistake in PR description. Fixed it.

[SET001]

also, maybe same changes might be applied in add_systems ?

[james7132]

This behavior should be documented in the doc comments.

[alice-i-cecile]

also, maybe same changes might be applied in add_systems ?

Yes, definitely. And agreed with James about the doc comments: I think .in_schedule is the best place for that.

[SET001]

Isn't this part covered with some tests that also need to be updated? I can't find any...

[JoJoJet]

Thanks for the PR! I think this is a good change. In addition to the others' feedback, I have a bit of my own.

Also, please run cargo fmt --all. That should fix the CI issues :)

[alice-i-cecile]

Isn't this part covered with some tests that also need to be updated? I can't find any...

I'm not surprised if there aren't any: we tend not to test this sort of end-user API super hard since it gets caught readily in the examples.

That said, I'd be happy to see a pair of tests for this behavior, one for the single system case and the other for multiple systems.

[SET001]

how can I test that system runs on a specified schedule? Like in this example, to test that it runs not on default?

[alice-i-cecile]

Use app.world.run_schedule(MySchedule) and then verify that the world was mutated as expected :)

[SET001]

That said, I'd be happy to see a pair of tests for this behavior, one for the single system case and the other for multiple systems.

should these tests be integration tests, in bevy_app/tests or it will be ok to place them in crates/bevy_app/src/app.rs test section ?

[alice-i-cecile]

The last one will work great here :)

[SET001]

Yes, definitely. And agreed with James about the doc comments: I think .in_schedule is the best place for that.

maybe for add_system as well?

[JoJoJet]

This looks correct now. It's probably also worth mentioning in the docs for add_state that the OnEnter and OnExit schedules only get added if they don't already exist.