Add more examples and tests for run criteria

[alice-i-cecile]

Currently there are no examples and limited tests for these.

We should add both.

[hymm]

There's some tests here:

bevy/crates/bevy_ecs/src/schedule/stage.rs

Lines 1432 to 1562 in 6615b7b

	fn parallel_run_criteria() {
	let mut world = World::new();
	world.insert_resource(Vec::<usize>::new());
	let mut stage = SystemStage::parallel()
	.with_system(
	make_parallel(0)
	.label("0")
	.with_run_criteria(every_other_time),
	)
	.with_system(make_parallel(1).after("0"));
	stage.run(&mut world);
	stage.run(&mut world);
	stage.set_executor(Box::new(SingleThreadedExecutor::default()));
	stage.run(&mut world);
	stage.run(&mut world);
	assert_eq!(
	*world.get_resource::<Vec<usize>>().unwrap(),
	vec![0, 1, 1, 0, 1, 1]
	);
	world.get_resource_mut::<Vec<usize>>().unwrap().clear();
	let mut stage = SystemStage::parallel()
	.with_system(make_parallel(0).before("1"))
	.with_system_set(
	SystemSet::new()
	.with_run_criteria(every_other_time)
	.with_system(make_parallel(1).label("1")),
	)
	.with_system(make_parallel(2).after("1"));
	stage.run(&mut world);
	stage.run(&mut world);
	stage.set_executor(Box::new(SingleThreadedExecutor::default()));
	stage.run(&mut world);
	stage.run(&mut world);
	assert_eq!(
	*world.get_resource::<Vec<usize>>().unwrap(),
	vec![0, 1, 2, 0, 2, 0, 1, 2, 0, 2]
	);
	// Reusing criteria.
	world.get_resource_mut::<Vec<usize>>().unwrap().clear();
	let mut stage = SystemStage::parallel()
	.with_system_run_criteria(every_other_time.label("every other time"))
	.with_system(make_parallel(0).before("1"))
	.with_system(
	make_parallel(1)
	.label("1")
	.with_run_criteria("every other time"),
	)
	.with_system(
	make_parallel(2)
	.label("2")
	.after("1")
	.with_run_criteria("every other time"),
	)
	.with_system(make_parallel(3).after("2"));
	stage.run(&mut world);
	stage.run(&mut world);
	stage.set_executor(Box::new(SingleThreadedExecutor::default()));
	stage.run(&mut world);
	stage.run(&mut world);
	assert_eq!(
	*world.get_resource::<Vec<usize>>().unwrap(),
	vec![0, 1, 2, 3, 0, 3, 0, 1, 2, 3, 0, 3]
	);
	assert_eq!(stage.run_criteria.len(), 1);
	// Piping criteria.
	world.get_resource_mut::<Vec<usize>>().unwrap().clear();
	fn eot_piped(input: In<ShouldRun>, has_ran: Local<bool>) -> ShouldRun {
	if let ShouldRun::Yes | ShouldRun::YesAndCheckAgain = input.0 {
	every_other_time(has_ran)
	} else {
	ShouldRun::No
	}
	}
	let mut stage = SystemStage::parallel()
	.with_system(make_parallel(0).label("0"))
	.with_system(
	make_parallel(1)
	.label("1")
	.after("0")
	.with_run_criteria(every_other_time.label("every other time")),
	)
	.with_system(make_parallel(2).label("2").after("1").with_run_criteria(
	RunCriteria::pipe("every other time", IntoSystem::into_system(eot_piped)),
	))
	.with_system(
	make_parallel(3).label("3").after("2").with_run_criteria(
	"every other time"
	.pipe(IntoSystem::into_system(eot_piped))
	.label("piped"),
	),
	)
	.with_system(make_parallel(4).after("3").with_run_criteria("piped"));
	for _ in 0..4 {
	stage.run(&mut world);
	}
	stage.set_executor(Box::new(SingleThreadedExecutor::default()));
	for _ in 0..5 {
	stage.run(&mut world);
	}
	assert_eq!(
	*world.get_resource::<Vec<usize>>().unwrap(),
	vec![0, 1, 2, 3, 4, 0, 0, 1, 0, 0, 1, 2, 3, 4, 0, 0, 1, 0, 0, 1, 2, 3, 4]
	);
	assert_eq!(stage.run_criteria.len(), 3);
	// Discarding extra criteria with matching labels.
	world.get_resource_mut::<Vec<usize>>().unwrap().clear();
	let mut stage =
	SystemStage::parallel()
	.with_system(make_parallel(0).before("1"))
	.with_system(make_parallel(1).label("1").with_run_criteria(
	every_other_time.label_discard_if_duplicate("every other time"),
	))
	.with_system(make_parallel(2).label("2").after("1").with_run_criteria(
	every_other_time.label_discard_if_duplicate("every other time"),
	))
	.with_system(make_parallel(3).after("2"));
	stage.run(&mut world);
	stage.run(&mut world);
	stage.set_executor(Box::new(SingleThreadedExecutor::default()));
	stage.run(&mut world);
	stage.run(&mut world);
	assert_eq!(
	*world.get_resource::<Vec<usize>>().unwrap(),
	vec![0, 1, 2, 3, 0, 3, 0, 1, 2, 3, 0, 3]
	);
	assert_eq!(stage.run_criteria.len(), 1);

[james7132]

#7652 adds an example for run conditions, and though it seems like the tests that @hymm are no longer there after stageless's merge. Perhaps we should add those tests back in.

[LiamGallagher737]

I'm happy to add in some more tests, would theses go the conditions.rs file?
https://github.com/bevyengine/bevy/blob/main/crates/bevy_ecs/src/schedule/condition.rs

[alice-i-cecile]

Yes please, I would add a mod tests there.