feat: Added size parameter for testGolden() (#1780)

Added size parameter to testGolden() function, allowing us to reduce the size of the game canvas used. The default size is 2400x1800, as given by the Flutter framework, seems like too much for most tests.

packages/flame_test/lib/src/test_golden.dart

@@ -1,4 +1,5 @@
 import 'package:flame/game.dart';
+import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:meta/meta.dart';
 
@@ -23,29 +24,47 @@ import 'package:meta/meta.dart';
 /// necessary game components, and possibly advancing the game clock. As a
 /// convenience, we will run `await game.ready()` before rendering, to ensure
 /// that all components that might be pending are properly mounted.
+///
+/// The [size] parameter controls the size of the "device" on which the game
+/// widget is rendered, if omitted it defaults to 2400x1800. This size will be
+/// equal to the canvas size of the game.
 @isTest
 void testGolden(
  String testName,
  PrepareGameFunction testBody, {
  required String goldenFile,
+ Vector2? size,
  FlameGame? game,
  bool skip = false,
 }) {
  testWidgets(
  testName,
  (tester) async {
  final gameInstance = game ?? FlameGame();
+ const myKey = ValueKey('game-instance');
 
  await tester.runAsync(() async {
- await tester.pumpWidget(GameWidget(game: gameInstance));
+ Widget widget = GameWidget(key: myKey, game: gameInstance);
+ if (size != null) {
+ widget = Center(
+ child: SizedBox(
+ width: size.x,
+ height: size.y,
+ child: RepaintBoundary(
+ child: widget,
+ ),
+ ),
+ );
+ }
+ await tester.pumpWidget(widget);
  await tester.pump();
  await testBody(gameInstance);
  await gameInstance.ready();
  await tester.pump();
  });
 
  await expectLater(
- find.byWidgetPredicate((widget) => widget is GameWidget),
+ find.byKey(myKey),
  matchesGoldenFile(goldenFile),
  );
  },

packages/flame_test/test/golden_test.dart

@@ -38,6 +38,18 @@ void main() {
  goldenFile: 'golden_test.png',
  );
 
+ testGolden(
+ 'Same test, but with smaller size',
+ (game) async {
+ final paint = Paint()..color = Colors.white;
+ game.add(
+ CircleComponent(radius: 10, position: Vector2.all(100), paint: paint),
+ );
+ },
+ size: Vector2(200, 200),
+ goldenFile: 'golden_test_small.png',
+ );
+
  testGolden(
  'skipped test',
  (game) async {},