Testbed: add a constructor that calls a custom closure with bevy’s App

examples3d-f64/debug_serialized3.rs

@@ -18,7 +18,7 @@ pub fn init_world(testbed: &mut Testbed) {
      * Set up the testbed.
      */
     let bytes = std::fs::read("state.bin").unwrap();
-    let mut state: State = bincode::deserialize(&bytes).unwrap();
+    let state: State = bincode::deserialize(&bytes).unwrap();
 
     testbed.set_world(
         state.bodies,

src_testbed/testbed.rs

@@ -227,7 +227,11 @@ impl TestbedApp {
         self.builders = SceneBuilders(builders)
     }
 
-    pub fn run(mut self) {
+    pub fn run(self) {
+        self.run_with_init(|_| {})
+    }
+
+    pub fn run_with_init(mut self, mut init: impl FnMut(&mut App)) {
         let mut args = env::args();
         let mut benchmark_mode = false;
 
@@ -392,8 +396,9 @@ impl TestbedApp {
                 .insert_non_send_resource(self.plugins)
                 .add_stage_before(CoreStage::Update, "physics", SystemStage::single_threaded())
                 .add_system_to_stage("physics", update_testbed.system())
-                .add_system(egui_focus.system())
-                .run();
+                .add_system(egui_focus.system());
+            init(&mut app);
+            app.run();
         }
     }
 }