fix!: Update should be called before render in first tick (#2714)

Previously render was called before the first update was called, which should be considered as a bug.

packages/flame/lib/src/game/game_widget/game_widget.dart

@@ -196,6 +196,9 @@ class GameWidgetState<T extends Game> extends State<GameWidget<T>> {
           await onLoad;
         }
         game.mount();
+        if (!game.paused) {
+          game.update(0);
+        }
       })();
 
   Future<void>? _loaderFuture;
@@ -362,6 +365,12 @@ class GameWidgetState<T extends Game> extends State<GameWidget<T>> {
                             Container();
                       }
                       currentGame.onGameResize(size);
+                      // This should only be called if the game has already been
+                      // loaded (in the case of resizing for example), since
+                      // update otherwise should be called after onMount.
+                      if (!currentGame.paused && currentGame.isAttached) {
+                        currentGame.update(0);
+                      }
                       return FutureBuilder(
                         future: loaderFuture,
                         builder: (_, snapshot) {

packages/flame/test/components/mixins/snapshot_test.dart

@@ -16,8 +16,8 @@ void main() {
         'Snapshot should be created once',
         _SnapshotTestGame.new,
         (game) async {
-          final snapshotComponent = game.snapshotComponent;
           await game.ready();
+          final snapshotComponent = game.snapshotComponent;
 
           // Wait a few frames
           final canvas = Canvas(PictureRecorder());
@@ -39,8 +39,8 @@ void main() {
         'Should render normally when renderSnapshot is false',
         () => _SnapshotTestGame(renderSnapshot: false),
         (game) async {
-          final snapshotComponent = game.snapshotComponent;
           await game.ready();
+          final snapshotComponent = game.snapshotComponent;
 
           // Wait a few frames
           const framesToWait = 5;
@@ -73,14 +73,15 @@ void main() {
         'Should generate a snapshot when takeSnapshot is called',
         (tester) async {
           final game = _SnapshotTestGame(renderSnapshot: false);
-          final snapshotComponent = game.snapshotComponent;
           const framesToWait = 5;
+          late final _MockSnapshotComponent snapshotComponent;
 
           await tester.runAsync(() async {
             final widget = GameWidget(game: game);
             await tester.pumpWidget(widget);
             await tester.pump();
             await game.ready();
+            snapshotComponent = game.snapshotComponent;
 
             // Wait a few frames
             final recorder = PictureRecorder();
@@ -116,13 +117,14 @@ void main() {
         'Should generate a transformed image',
         (tester) async {
           final game = _SnapshotTestGame(renderSnapshot: false);
-          final snapshotComponent = game.snapshotComponent;
+          late final _MockSnapshotComponent snapshotComponent;
 
           await tester.runAsync(() async {
             final widget = GameWidget(game: game);
             await tester.pumpWidget(widget);
             await tester.pump();
             await game.ready();
+            snapshotComponent = game.snapshotComponent;
 
             // Force a frame
             final canvas = Canvas(PictureRecorder());
@@ -173,8 +175,12 @@ void main() {
 
 class _SnapshotTestGame extends FlameGame {
   late final _MockSnapshotComponent snapshotComponent;
+  bool renderSnapshot;
 
-  _SnapshotTestGame({bool renderSnapshot = true}) {
+  _SnapshotTestGame({this.renderSnapshot = true});
+
+  @override
+  Future<void> onLoad() async {
     // Add a snapshot-enabled component that has it's own rendered content
     snapshotComponent = _MockSnapshotComponent()
       ..size = Vector2(200, 200)

packages/flame/test/game/game_widget/game_widget_lifecycle_test.dart

@@ -25,6 +25,18 @@ class _MyGame extends FlameGame {
     events.add('onMount');
   }
 
+  @override
+  void update(double dt) {
+    super.update(dt);
+    events.add('update');
+  }
+
+  @override
+  void render(Canvas canvas) {
+    super.render(canvas);
+    events.add('render');
+  }
+
   @override
   void onRemove() {
     super.onRemove();
@@ -207,12 +219,27 @@ void main() {
       state.causeResize();
 
       await tester.pump();
-      expect(events, ['onGameResize']); // no onRemove
+      expect(events, ['onGameResize', 'update', 'render']); // no onRemove
       final game =
           tester.allWidgets.whereType<GameWidget<_MyGame>>().first.game;
       expect(game?.children, everyElement((Component c) => c.parent == game));
     });
 
+    testWidgets('update is not called when game is paused', (tester) async {
+      final events = <String>[];
+      await tester.pumpWidget(_MyContainer(events));
+
+      events.clear();
+      tester.allWidgets
+          .whereType<GameWidget<_MyGame>>()
+          .first
+          .game
+          ?.pauseEngine();
+      await tester.pump();
+      await tester.pump();
+      expect(events, ['render']);
+    });
+
     testWidgets('all events are executed in the correct order', (tester) async {
       final events = <String>[];
       await tester.pumpWidget(_MyApp(events));
@@ -239,10 +266,15 @@ void main() {
           'onGameResize',
           'onLoad',
           'onMount',
+          'update',
+          'render',
+          'update',
           'onRemove',
           'onDispose',
           'onGameResize',
           'onMount',
+          'update',
+          'render',
         ],
       );
     });

packages/flame/test/game/game_widget/game_widget_pause_test.dart

@@ -52,15 +52,21 @@ class _WrapperState extends State<_Wrapper> {
 }
 
 class _MyGame extends FlameGame {
-  int callCount = 0;
+  int updateCount = 0;
+  int renderCount = 0;
   double timePassed = 0;
 
   @override
   void update(double dt) {
     super.update(dt);
     timePassed += dt;
+    updateCount++;
+  }
 
-    callCount++;
+  @override
+  void render(Canvas canvas) {
+    super.render(canvas);
+    renderCount++;
   }
 }
 
@@ -86,7 +92,8 @@ void main() {
       // shouldn't run another frame on the game
       await tester.pump();
 
-      expect(game.callCount, equals(2));
+      // Remember that there is one initial update(0) called.
+      expect(game.updateCount, equals(3));
     },
   );
 
@@ -105,7 +112,8 @@ void main() {
       game.resumeEngine();
       await tester.pump();
 
-      expect(game.callCount, equals(3));
+      // Remember that there is one initial update(0) called.
+      expect(game.updateCount, equals(4));
     },
   );
 
@@ -121,7 +129,8 @@ void main() {
       await tester.tap(find.text('Toggle'));
       await tester.pumpAndSettle();
 
-      expect(game.callCount, equals(2));
+      // Remember that there is one initial update(0) called.
+      expect(game.updateCount, equals(3));
     },
   );
 
@@ -132,7 +141,7 @@ void main() {
       await tester.pump();
       await tester.pump();
 
-      expect(game.callCount, equals(0));
+      expect(game.updateCount, equals(0));
     },
   );
 
@@ -149,7 +158,7 @@ void main() {
       await tester.pump();
       await tester.pump();
 
-      expect(game.callCount, equals(2));
+      expect(game.updateCount, equals(2));
     },
   );
 
@@ -173,7 +182,8 @@ void main() {
       await tester.pump(const Duration(seconds: 100));
       await tester.pump(frameLength);
 
-      expect(game.callCount, equals(4));
+      // Remember that there is one initial update(0) after mount
+      expect(game.updateCount, equals(5));
       expect(game.timePassed, equals(3));
     },
   );