mutate observer unit test

crates/bevy_ecs/src/storage/entity_change.rs

@@ -52,4 +52,28 @@ impl EntityChange {
     pub fn component(&self) -> ComponentId {
         self.component
     }
+}
+
+mod tests {
+    use crate::component::ComponentId;
+    use crate::entity::Entity;
+    use crate::storage::{Changes, EntityChange};
+
+    #[test]
+    fn changes() {
+        let mut storage = Changes::new();
+        let entity = Entity::PLACEHOLDER;
+        let component = ComponentId::new(1);
+        storage.push(EntityChange::new(entity, component));
+        storage.push(EntityChange::new(entity, component));
+
+        let changes = storage.take_all();
+        assert_eq!(changes.len(), 2);
+        assert_eq!(storage.take_all().len(), 0);
+
+        changes.iter().for_each(|change| {
+            assert_eq!(change.component, component);
+            assert_eq!(change.entity, entity);
+        })
+    }
 }

crates/bevy_ecs/src/world/mod.rs

@@ -136,14 +136,6 @@ pub struct World {
     pub(crate) command_queue: RawCommandQueue,
 }
 
-impl World {
-
-    /// Just For Test
-    pub fn test(&mut self) -> &mut Changes {
-        &mut self.storages.changes
-    }
-}
-
 impl Default for World {
     fn default() -> Self {
         let mut world = Self {