try to fix ci

--still broken

crates/bevy_app/src/app.rs

@@ -8,10 +8,9 @@ use bevy_ecs::{
         SystemStage,
     },
     system::Resource,
-
     world::World,
 };
-use bevy_tasks::ComputeTaskPool;
+use bevy_tasks::{ComputeTaskPool, TaskPool};
 use bevy_utils::{tracing::debug, HashMap, HashSet};
 use std::fmt::Debug;
 
@@ -154,7 +153,7 @@ impl App {
     pub fn update(&mut self) {
         #[cfg(feature = "trace")]
         let _bevy_frame_update_span = info_span!("frame").entered();
-        ComputeTaskPool::get().scope(|scope| {
+        ComputeTaskPool::init(TaskPool::default).scope(|scope| {
             if self.run_once {
                 for sub_app in self.sub_apps.values_mut() {
                     (sub_app.extract)(&mut self.world, &mut sub_app.app);

crates/bevy_tasks/src/main_thread_executor.rs

@@ -10,7 +10,10 @@ static MAIN_THREAD_EXECUTOR: OnceCell<MainThreadExecutor> = OnceCell::new();
 /// Use to access the global main thread executor. Be aware that the main thread executor
 /// only makes progress when it is ticked. This normally happens in `[TaskPool::scope]`.
 #[derive(Debug)]
-pub struct MainThreadExecutor(Arc<Executor<'static>>);
+pub struct MainThreadExecutor(
+    // this is only pub crate for testing purposes, do not contruct otherwise
+    pub(crate) Arc<Executor<'static>>,
+);
 
 impl MainThreadExecutor {
     /// Initializes the global `[MainThreadExecutor]` instance.
@@ -39,6 +42,17 @@ impl MainThreadExecutor {
     /// Use this to tick the main thread executor.
     /// Returns None if called on not the main thread.
     pub fn ticker(&self) -> Option<MainThreadTicker> {
+        // always return ticker when testing to allow tests to run off main thread
+        dbg!("hjj");
+        #[cfg(test)]
+        if true {
+            dbg!("blah");
+            return Some(MainThreadTicker {
+                executor: self.0.clone(),
+                _marker: PhantomData::default(),
+            });
+        }
+
         if let Some(is_main) = is_main_thread() {
             if is_main {
                 return Some(MainThreadTicker {
@@ -69,7 +83,7 @@ pub struct MainThreadTicker {
 impl MainThreadTicker {
     /// Tick the main thread executor.
     /// This needs to be called manually on the main thread if a `[TaskPool::scope]` is not active
-    pub fn tick<'a>(&'a self) -> impl Future<Output = ()> + 'a {
+    pub fn tick(&self) -> impl Future<Output = ()> + '_ {
         self.executor.tick()
     }
 }

crates/bevy_tasks/src/task_pool.rs

@@ -245,7 +245,15 @@ impl TaskPool {
         // transmute the lifetimes to 'env here to appease the compiler as it is unable to validate safety.
         let executor: &async_executor::Executor = &self.executor;
         let executor: &'env async_executor::Executor = unsafe { mem::transmute(executor) };
-        let main_thread_spawner = MainThreadExecutor::init().spawner();
+
+        #[cfg(not(test))]
+        let main_thread_executor = MainThreadExecutor::init();
+        // for testing configure a new instance of main thread executor for every scope
+        // this helps us pretend that the thread that an app or stage is constructed on is the main thread
+        #[cfg(test)]
+        let main_thread_executor = MainThreadExecutor(Arc::new(async_executor::Executor::new()));
+
+        let main_thread_spawner = main_thread_executor.spawner();
         let main_thread_spawner: MainThreadSpawner<'env> =
             unsafe { mem::transmute(main_thread_spawner) };
         let spawned: ConcurrentQueue<async_executor::Task<T>> = ConcurrentQueue::unbounded();
@@ -277,9 +285,10 @@ impl TaskPool {
                     results
                 };
 
-                if let Some(main_thread_ticker) = MainThreadExecutor::get().ticker() {
+                if let Some(main_thread_ticker) = main_thread_executor.ticker() {
                     let tick_forever = async move {
                         loop {
+                            dbg!("tivk");
                             main_thread_ticker.tick().await;
                         }
                     };
@@ -441,7 +450,7 @@ mod tests {
     }
 
     #[test]
-    fn test_mixed_spawn_on_scope_and_spawn() {
+    fn test_mixed_spawn_on_main_and_spawn() {
         let pool = TaskPool::new();
 
         let foo = Box::new(42);