fix: make check-unnecessary-nullable command ignore Flutter keys (#994)

Author: incendial

CHANGELOG.md

@@ -8,6 +8,7 @@
 * fix: support variables shadowing for [`avoid-unused-parameters`](https://dartcodemetrics.dev/docs/rules/common/avoid-unused-parameters).
 * fix: support not named builder parameters for [`avoid-returning-widgets`](https://dartcodemetrics.dev/docs/rules/flutter/avoid-returning-widgets).
 * feat: make [`avoid-unnecessary-type-assertions`](https://dartcodemetrics.dev/docs/rules/common/avoid-unnecessary-type-assertions) handle is! checks.
+* fix: make check-unnecessary-nullable command ignore Flutter keys.
 * chore: restrict `analyzer` version to `>=4.1.0 <4.8.0`.
 
 ## 4.18.0-dev.2

lib/src/analyzers/unnecessary_nullable_analyzer/unnecessary_nullable_analyzer.dart

@@ -18,6 +18,7 @@ import '../../config_builder/config_builder.dart';
 import '../../config_builder/models/analysis_options.dart';
 import '../../reporters/models/reporter.dart';
 import '../../utils/analyzer_utils.dart';
+import '../../utils/flutter_types_utils.dart';
 import '../../utils/suppression.dart';
 import 'declarations_visitor.dart';
 import 'invocations_visitor.dart';
@@ -227,6 +228,7 @@ class UnnecessaryNullableAnalyzer {
 
     final unnecessaryNullable = parameters.where(
       (parameter) =>
+          !_shouldIgnoreWidgetKey(parameter) &&
           !markedParameters.contains(parameter) &&
           parameter.declaredElement?.type.nullabilitySuffix ==
               NullabilitySuffix.question,
@@ -300,4 +302,15 @@ class UnnecessaryNullableAnalyzer {
       ),
     );
   }
+
+  bool _shouldIgnoreWidgetKey(FormalParameter parameter) {
+    final closestDeclaration = parameter.parent?.parent;
+
+    if (closestDeclaration is ConstructorDeclaration) {
+      return parameter.identifier?.name == 'key' &&
+          isWidgetOrSubclass(closestDeclaration.declaredElement?.returnType);
+    }
+
+    return false;
+  }
 }

test/resources/unnecessary_nullable_analyzer/nullable_widget_key_parameters.dart

@@ -0,0 +1,17 @@
+class MyWidget extends StatelessWidget {
+  const MyWidget(Key? key) : super(key);
+}
+
+class Widget {
+  final Key? key;
+
+  const Widget(this.key);
+}
+
+class StatelessWidget extends Widget {
+  const StatelessWidget(Key? key) : super(key);
+}
+
+class Key {}
+
+class GlobalKey extends Key {}

test/resources/unnecessary_nullable_analyzer/unnecessary_nullable_example.dart

@@ -3,6 +3,7 @@
 import 'nullable_class_parameters.dart';
 import 'nullable_function_parameters.dart';
 import 'nullable_method_parameters.dart';
+import 'nullable_widget_key_parameters.dart';
 import 'suppressed_file.dart';
 
 void main() {
@@ -41,6 +42,8 @@ void main() {
 
   multipleParametersWithNamed('name', 1, name: 'secondName');
   multipleParametersWithOptional('name', 1, 'secondName');
+
+  MyWidget(GlobalKey());
 }
 
 class _Test {

test/src/analyzers/unnecessary_nullable_analyzer/unnecessary_nullable_analyzer_test.dart

@@ -1,5 +1,6 @@
 import 'dart:io';
 
+import 'package:collection/collection.dart';
 import 'package:dart_code_metrics/src/analyzers/unnecessary_nullable_analyzer/models/unnecessary_nullable_file_report.dart';
 import 'package:dart_code_metrics/src/analyzers/unnecessary_nullable_analyzer/reporters/reporters_list/console/unnecessary_nullable_console_reporter.dart';
 import 'package:dart_code_metrics/src/analyzers/unnecessary_nullable_analyzer/unnecessary_nullable_analyzer.dart';
@@ -121,6 +122,16 @@ void main() {
           expect(thirdIssue.location.line, 25);
           expect(thirdIssue.location.column, 1);
         });
+
+        test(
+          'should analyze ignored parameters and report no issues',
+          () async {
+            final report = result.firstWhereOrNull((report) =>
+                report.path.endsWith('nullable_widget_key_parameters.dart'));
+
+            expect(report, isNull);
+          },
+        );
       });
 
       test('should return a reporter', () {