Move use_key_in_widget_constructors tests to be reflective (#4283)

Author: srawlins

test/rule_test_support.dart

@@ -469,14 +469,43 @@ abstract class BuildContext {
   bool get mounted;
 }
 
+class Container extends StatelessWidget {
+  const Container({super.key});
+}
+
+class Key {
+  Key(String value);
+}
+
 class Navigator {
   static NavigatorState of(
       BuildContext context, {bool rootNavigator = false}) => NavigatorState();
 }
 
 class NavigatorState {}
 
-class Widget {}
+abstract class StatefulWidget extends Widget {
+  const StatefulWidget({super.key});
+}
+
+abstract class Widget {
+  final Key? key;
+
+  const Widget({thi.key});
+}
+
+abstract class StatelessWidget extends Widget {
+  const StatelessWidget({super.key});
+
+  @protected
+  Widget build(BuildContext context);
+}
+
+abstract class Widget {
+  final Key? key;
+
+  const Widget({thi.key});
+}
 ''');
   }
 }

test/rules/all.dart

@@ -133,6 +133,8 @@ import 'use_build_context_synchronously_test.dart'
 import 'use_enums_test.dart' as use_enums;
 import 'use_is_even_rather_than_modulo_test.dart'
     as use_is_even_rather_than_modulo;
+import 'use_key_in_widget_constructors_test.dart'
+    as use_key_in_widget_constructors;
 import 'use_late_for_private_fields_and_variables_test.dart'
     as use_late_for_private_fields_and_variables;
 import 'use_named_constants_test.dart' as use_named_constants;
@@ -236,6 +238,7 @@ void main() {
   use_build_context_synchronously.main();
   use_enums.main();
   use_is_even_rather_than_modulo.main();
+  use_key_in_widget_constructors.main();
   use_late_for_private_fields_and_variables.main();
   use_named_constants.main();
   use_super_parameters.main();

test/rules/use_key_in_widget_constructors_test.dart

@@ -0,0 +1,156 @@
+// Copyright (c) 2023, 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(UseKeyInWidgetConstructorsTest);
+  });
+}
+
+@reflectiveTest
+class UseKeyInWidgetConstructorsTest extends LintRuleTest {
+  @override
+  bool get addFlutterPackageDep => true;
+
+  @override
+  String get lintRule => 'use_key_in_widget_constructors';
+
+  test_constNamedConstructor_missingKey() async {
+    await assertDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+abstract class MyWidget extends StatelessWidget {
+  const MyWidget.named();
+}
+''', [
+      lint(107, 5),
+    ]);
+  }
+
+  test_constUnnamedConstructor_missingKey() async {
+    await assertDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+abstract class MyWidget extends StatelessWidget {
+  const MyWidget();
+}
+''', [
+      lint(98, 8),
+    ]);
+  }
+
+  test_factoryConstructor() async {
+    await assertNoDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+class MyWidget extends StatelessWidget {
+  MyWidget({super.key});
+  factory MyWidget.fact() => MyWidget();
+  @override
+  Widget build(BuildContext context) => Container();
+}
+''');
+  }
+
+  test_missingConstructor() async {
+    await assertDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+class NoConstructorWidget extends StatefulWidget {}
+''', [
+      lint(46, 19),
+    ]);
+  }
+
+  test_missingKey() async {
+    await assertDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+abstract class MyWidget extends StatelessWidget {
+  MyWidget();
+}
+''', [
+      lint(92, 8),
+    ]);
+  }
+
+  test_missingKey_keyPassedToSuper() async {
+    await assertNoDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+abstract class MyWidget extends StatelessWidget {
+  MyWidget.superCall() : super(key: Key(''));
+}
+''');
+  }
+
+  test_privateClass() async {
+    await assertNoDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+// ignore: unused_element
+class _PrivateWidget extends StatefulWidget {}
+''');
+  }
+
+  test_privateConstructor() async {
+    await assertNoDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+abstract class MyWidget extends StatelessWidget {
+  MyWidget._private();
+}
+''');
+  }
+
+  test_redirectingConstructor_withKey() async {
+    await assertNoDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+abstract class MyWidget extends StatelessWidget {
+  MyWidget.redirect() : this.withKey(key: Key(''));
+  MyWidget.withKey({Key? key}) : super(key: key ?? Key(''));
+}
+''');
+  }
+
+  test_simpleFormalParameter_notPassedToSuper() async {
+    await assertDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+abstract class MyWidget extends StatelessWidget {
+  MyWidget.withKey({Key? key});
+}
+''', [
+      lint(101, 7),
+    ]);
+  }
+
+  test_simpleFormalParameter_passedToSuper() async {
+    await assertNoDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+abstract class MyWidget extends StatelessWidget {
+  MyWidget.withKey({Key? key}) : super(key: key ?? Key(''));
+}
+''');
+  }
+
+  test_superParameter() async {
+    await assertNoDiagnostics(r'''
+import 'package:flutter/widgets.dart';
+
+class OtherWidget extends StatelessWidget {
+  const OtherWidget({required super.key});
+
+  @override
+  Widget build(BuildContext context) => Container();
+}
+''');
+  }
+}