Improve `update_icons.dart` script (#93863)

* Update update_icons.dart

* formatting

* more formatting

* simplify safety checks

* add safety checks tests

* formatting

* update copyright

* naming

* revert copyright

* add `fontFamily` option

* tweak diff messages

* Update update_icons.dart

* don't exit if platform adaptive icon not found

* remove trailing spaces

* remove warning and fix insert_chart (outlined) dartdoc

* x

* add error message when exiting due to failed safety checkes

* fix icon reference

* fix rewrite for onetwothree

dev/tools/test/update_icons_test.dart

+// Copyright 2014 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 'package:test/test.dart';
+
+import '../update_icons.dart';
+
+Map<String, String> codepointsA = <String, String>{
+  'airplane': '111',
+  'boat': '222',
+};
+Map<String, String> codepointsB = <String, String>{
+  'airplane': '333',
+};
+Map<String, String> codepointsC = <String, String>{
+  'airplane': '111',
+  'train': '444',
+};
+
+void main() {
+  group('safety checks', () {
+    test('superset', () {
+      expect(testIsSuperset(codepointsA, codepointsA), true);
+
+      expect(testIsSuperset(codepointsA, codepointsB), true);
+      expect(testIsSuperset(codepointsB, codepointsA), false);
+    });
+    test('stability', () {
+      expect(testIsStable(codepointsA, codepointsA), true);
+
+      expect(testIsStable(codepointsA, codepointsB), false);
+      expect(testIsStable(codepointsB, codepointsA), false);
+
+      expect(testIsStable(codepointsA, codepointsC), true);
+      expect(testIsStable(codepointsC, codepointsA), true);
+    });
+  });
+}

packages/flutter/lib/src/material/icons.dart

@@ -97,8 +97,7 @@ class PlatformAdaptiveIcons implements Icons {
 ///
 /// Use with the [Icon] class to show specific icons.
 ///
-/// Icons are identified by their name as listed below. **Do not use codepoints
-/// directly, as they are subject to change.**
+/// Icons are identified by their name as listed below, e.g. [Icons.airplanemode_on].
 ///
 /// To use this class, make sure you set `uses-material-design: true` in your
 /// project's `pubspec.yaml` file in the `flutter` section. This ensures that
@@ -10287,7 +10286,7 @@ class Icons {
   /// <i class="material-icons-round md-36">insert_chart</i> &#x2014; material icon named "insert chart" (round).
   static const IconData insert_chart_rounded = IconData(0xf819, fontFamily: 'MaterialIcons');
 
-  /// <i class="material-icons md-36">insert_chart_outlined</i> &#x2014; material icon named "insert chart outlined".
+  /// <i class="material-icons-outlined md-36">insert_chart</i> &#x2014; material icon named "insert chart" (outlined).
   static const IconData insert_chart_outlined = IconData(0xf12a, fontFamily: 'MaterialIcons');
 
   /// <i class="material-icons-sharp md-36">insert_chart_outlined</i> &#x2014; material icon named "insert chart outlined" (sharp).