enhanced enum support for avoid_equals_and_hash_code_on_mutable_classes (dart-archive/linter#3233)

* enhanced enum support for `avoid_equals_and_hash_code_on_mutable_classes`

* - stale todo

* fmt

* test update

* fmt

Author: pq

test/rules/all.dart

@@ -5,6 +5,8 @@
 import 'annotate_overrides_test.dart' as annotate_overrides;
 import 'avoid_annotating_with_dynamic_test.dart'
     as avoid_annotating_with_dynamic;
+import 'avoid_equals_and_hash_code_on_mutable_classes_test.dart'
+    as avoid_equals_and_hash_code_on_mutable_classes;
 import 'avoid_function_literals_in_foreach_calls_test.dart'
     as avoid_function_literals_in_foreach_calls;
 import 'avoid_init_to_null_test.dart' as avoid_init_to_null;
@@ -68,6 +70,7 @@ import 'void_checks_test.dart' as void_checks;
 void main() {
   annotate_overrides.main();
   avoid_annotating_with_dynamic.main();
+  avoid_equals_and_hash_code_on_mutable_classes.main();
   avoid_function_literals_in_foreach_calls.main();
   avoid_setters_without_getters.main();
   avoid_init_to_null.main();

test/rules/avoid_equals_and_hash_code_on_mutable_classes_test.dart

@@ -0,0 +1,43 @@
+// Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file
+// for details. 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_reflective_loader/test_reflective_loader.dart';
+
+import '../rule_test_support.dart';
+
+main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(AvoidEqualsAndHashCodeOnMutableClassesTest);
+  });
+}
+
+@reflectiveTest
+class AvoidEqualsAndHashCodeOnMutableClassesTest extends LintRuleTest {
+  @override
+  bool get addMetaPackageDep => true;
+
+  @override
+  List<String> get experiments => [
+        EnableString.enhanced_enums,
+      ];
+
+  @override
+  String get lintRule => 'avoid_equals_and_hash_code_on_mutable_classes';
+
+  @FailingTest(
+      issue: 'https://github.com/dart-lang/linter/issues/3094',
+      reason: 'Needs new analyzer')
+  test_enums() async {
+    // Enums are constant by design.
+    await assertNoDiagnostics(r'''
+enum E {
+  e(1), f(2), g(3);
+  final int key;
+  const E(this.key);
+  bool operator ==(Object other) => other is E && other.key == key;
+  int get hashCode => key.hashCode;
+}
+''');
+  }
+}