Cupertino icons golden tests

CODEOWNERS

@@ -45,6 +45,7 @@ packages/web_benchmarks/**                               @yjbanov
 packages/webview_flutter/**                              @bparrishMines
 packages/xdg_directories/**                              @stuartmorgan
 third_party/packages/cupertino_icons/**                  @MitchellGoodwin
+third_party/packages/cupertino_icons/test/goldens/**     @LongCatIsLooong
 
 # Plugin platform implementation rules. These should stay last, since the last
 # matching entry takes precedence.

third_party/packages/cupertino_icons/pubspec.yaml

@@ -9,10 +9,12 @@ environment:
   sdk: ^3.3.0
 
 dev_dependencies:
+  collection: ^1.18.0
   flutter:
     sdk: flutter
   flutter_test:
     sdk: flutter
+  path: 1.9.0
 
 flutter:
   fonts:

third_party/packages/cupertino_icons/test/cupertino_icons_golden_test.dart

@@ -0,0 +1,87 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:io' show File, Platform;
+
+import 'package:collection/collection.dart';
+import 'package:flutter/cupertino.dart';
+import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:path/path.dart' as path;
+
+import 'icons_list.dart';
+
+// The EM of the font is 512. Keep this a power of 2 for fixed-point arithmetic.
+const double iconSize = 128.0;
+const int iconsPerRow = 5;
+const int iconsPerCol = 5;
+const int iconsPerImage = iconsPerRow * iconsPerCol;
+
+void main() async {
+  // Do not run on web since this test uses dart:io.
+  // The golden test runs on Linux only to avoid platform rendering differences.
+  if (kIsWeb || !Platform.isLinux) {
+    return;
+  }
+  final bool isMainChannel = !Platform.environment.containsKey('CHANNEL')
+    || Platform.environment['CHANNEL'] == 'main'
+    || Platform.environment['CHANNEL'] == 'master';
+  // Only test against main to avoid rendering differences between flutter channels.
+  if (!isMainChannel) {
+    return;
+  }
+  // Load font.
+  final String effectiveFontFamily = const TextStyle(fontFamily: CupertinoIcons.iconFont, package: CupertinoIcons.iconFontPackage).fontFamily!;
+  final FontLoader fontLoader = FontLoader(effectiveFontFamily);
+  final String filePath = path.canonicalize('assets/CupertinoIcons.ttf');
+  final File file = File(filePath);
+  fontLoader.addFont(file.readAsBytes().then((Uint8List v) => v.buffer.asByteData()));
+  await fontLoader.load();
+
+  assert(icons.isNotEmpty);
+  for (int index = 0; index < icons.length;) {
+    final int groupEndCodePoint = (icons[index].codePoint ~/ iconsPerImage + 1) * iconsPerImage;
+    final int next = icons.indexWhere((IconData icon) => icon.codePoint >= groupEndCodePoint, index);
+    final int nextIndex = next < 0 ? icons.length : next;
+    registerTestForIconGroup(icons.slice(index, nextIndex));
+    index = nextIndex;
+  }
+}
+
+// Generating goldens for each glyph is very slow. Group the sorted icons
+// into codepoint-aligned groups (each of which has a max capacity of
+// iconsPerRow * iconsPerCol), so the goldens are easier to review when
+// symbols are added or removed.
+void registerTestForIconGroup(List<IconData> iconGroup) {
+  assert(iconGroup.isNotEmpty);
+  String hexCodePoint(int codePoint) => codePoint.toRadixString(16).toUpperCase().padLeft(4, '0');
+  final int groupStartCodePoint = (iconGroup.first.codePoint ~/ iconsPerImage) * iconsPerImage;
+  final String range = 'U+${hexCodePoint(groupStartCodePoint)}-${hexCodePoint(groupStartCodePoint + iconsPerImage - 1)}';
+
+  testWidgets('font golden test: $range', (WidgetTester tester) async {
+    addTearDown(tester.view.reset);
+    const Size canvasSize = Size(iconSize * iconsPerRow, iconSize * iconsPerCol);
+    tester.view.physicalSize = canvasSize * tester.view.devicePixelRatio;
+
+    const Widget fillerBox = SizedBox.square(dimension: iconSize);
+    final List<Widget> children = List<Widget>.filled(iconsPerImage, fillerBox);
+    for (final IconData icon in iconGroup) {
+      children[icon.codePoint - groupStartCodePoint] = Icon(icon, size: iconSize);
+    }
+
+    final Widget widget = Directionality(
+      textDirection: TextDirection.ltr,
+      child: Center(
+        child: SizedBox(
+          height: iconSize * iconsPerCol,
+          width: iconSize * iconsPerRow,
+          child: RepaintBoundary(child: Wrap(children: children)),
+        ),
+      ),
+    );
+    await tester.pumpWidget(widget);
+    await expectLater(find.byType(Wrap) , matchesGoldenFile('goldens/glyph_$range.png'));
+  });
+}