Ignore magic numbers in widget parameters

lib/lints/no_magic_number/models/no_magic_number_parameters.dart

@@ -2,20 +2,28 @@
 /// parameters.
 class NoMagicNumberParameters {
   static const _allowedConfigName = 'allowed';
+  static const _allowedInWidgetParamsConfigName = 'allowed_in_widget_params';
   static const _defaultMagicNumbers = [-1, 0, 1];
 
   /// List of allowed numbers
   final Iterable<num> allowedNumbers;
 
+  /// The flag indicates whether magic numbers are allowed as a Widget instance
+  /// parameter.
+  final bool allowedInWidgetParams;
+
   /// Constructor for [NoMagicNumberParameters] model
   const NoMagicNumberParameters({
     required this.allowedNumbers,
+    required this.allowedInWidgetParams,
   });
 
   /// Method for creating from json data
   factory NoMagicNumberParameters.fromJson(Map<String, Object?> json) =>
       NoMagicNumberParameters(
         allowedNumbers:
             json[_allowedConfigName] as Iterable<num>? ?? _defaultMagicNumbers,
+        allowedInWidgetParams:
+            json[_allowedInWidgetParamsConfigName] as bool? ?? false,
       );
 }

lib/lints/no_magic_number/no_magic_number_rule.dart

@@ -22,7 +22,9 @@
 // SOFTWARE.
 
 import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/error/listener.dart';
+import 'package:collection/collection.dart';
 import 'package:custom_lint_builder/custom_lint_builder.dart';
 import 'package:solid_lints/lints/no_magic_number/models/no_magic_number_parameters.dart';
 import 'package:solid_lints/lints/no_magic_number/no_magic_number_visitor.dart';
@@ -71,7 +73,8 @@ class NoMagicNumberRule extends SolidLintRule<NoMagicNumberParameters> {
           .where(_isNotInsideIndexExpression)
           .where(_isNotInsideEnumConstantArguments)
           .where(_isNotDefaultValue)
-          .where(_isNotInConstructorInitializer);
+          .where(_isNotInConstructorInitializer)
+          .where(_isNotWidgetParameter);
 
       for (final magicNumber in magicNumbers) {
         reporter.reportErrorForNode(code, magicNumber);
@@ -132,4 +135,31 @@ class NoMagicNumberRule extends SolidLintRule<NoMagicNumberParameters> {
   bool _isNotInConstructorInitializer(Literal literal) {
     return literal.thisOrAncestorOfType<ConstructorInitializer>() == null;
   }
+
+  bool _isNotWidgetParameter(Literal literal) {
+    if (!config.parameters.allowedInWidgetParams) return true;
+
+    final widgetCreationExpression = literal.thisOrAncestorMatching(
+      _isWidgetCreationExpression,
+    );
+
+    return widgetCreationExpression == null;
+  }
+
+  bool _isWidgetCreationExpression(
+    AstNode node,
+  ) {
+    if (node is! InstanceCreationExpression) return false;
+
+    final staticType = node.staticType;
+
+    if (staticType is! InterfaceType) return false;
+
+    final widgetSupertype = staticType.allSupertypes.firstWhereOrNull(
+      (supertype) =>
+          supertype.getDisplayString(withNullability: false) == 'Widget',
+    );
+
+    return widgetSupertype != null;
+  }
 }

lint_test/no_magic_number_allowed_in_widget_params_test/analysis_options.yaml

@@ -0,0 +1,8 @@
+analyzer:
+  plugins:
+    - ../custom_lint
+
+custom_lint:
+  rules:
+    - no_magic_number:
+      allowed_in_widget_params: true

lint_test/no_magic_number_allowed_in_widget_params_test/no_magic_number_allowed_in_widget_params_test.dart

@@ -0,0 +1,27 @@
+// Allowed for numbers in a Widget subtype parameters.
+abstract interface class Widget {}
+
+class StatelessWidget implements Widget {}
+
+class MyWidget extends StatelessWidget {
+  final MyWidgetDecoration decoration;
+  final int value;
+
+  MyWidget({
+    required this.decoration,
+    required this.value,
+  });
+}
+
+class MyWidgetDecoration {
+  final int size;
+
+  MyWidgetDecoration({required this.size});
+}
+
+Widget build() {
+  return MyWidget(
+    decoration: MyWidgetDecoration(size: 12),
+    value: 23,
+  );
+}

lint_test/no_magic_number_allowed_in_widget_params_test/pubspec.yaml

@@ -0,0 +1,11 @@
+name: no_magic_number_allowed_in_widget_params_test
+description: A starting point for Dart libraries or applications.
+publish_to: none
+
+environment:
+  sdk: '>=3.0.0 <4.0.0'
+
+dev_dependencies:
+  solid_lints:
+    path: ../../
+  test: ^1.20.1

lint_test/no_magic_number_test.dart

@@ -86,3 +86,32 @@ class ConstructorInitializer {
 
   ConstructorInitializer() : value = 10;
 }
+
+abstract interface class Widget {}
+
+class StatelessWidget implements Widget {}
+
+class MyWidget extends StatelessWidget {
+  final MyWidgetDecoration decoration;
+  final int value;
+
+  MyWidget({
+    required this.decoration,
+    required this.value,
+  });
+}
+
+class MyWidgetDecoration {
+  final int size;
+
+  MyWidgetDecoration({required this.size});
+}
+
+Widget build() {
+  return MyWidget(
+    // expect_lint: no_magic_number
+    decoration: MyWidgetDecoration(size: 12),
+    // expect_lint: no_magic_number
+    value: 23,
+  );
+}