- Improved avoid_unrelated_type_assertions to support true and false results (#145)

- Improved `avoid_unrelated_type_assertions` to support true and false results

Author: aderhachev

CHANGELOG.md

@@ -8,6 +8,7 @@
   - no longer allows returning widgets from methods/functions named build
 - Fixed unexpected avoid_unnecessary_type_assertions
 - Added `excludeNames` param for `function_lines_of_code` lint
+- Improved `avoid_unrelated_type_assertions` to support true and false results
 
 ## 0.1.4
 

lib/src/lints/avoid_unrelated_type_assertions/avoid_unrelated_type_assertions_rule.dart

@@ -22,7 +22,7 @@ class AvoidUnrelatedTypeAssertionsRule extends SolidLintRule {
       configs: configs,
       name: lintName,
       problemMessage: (_) =>
-          'Avoid unrelated "is" assertion. The result is always "false".',
+          'Avoid unrelated "is" assertion. The result is always "{0}".',
     );
 
     return AvoidUnrelatedTypeAssertionsRule._(rule);
@@ -39,7 +39,11 @@ class AvoidUnrelatedTypeAssertionsRule extends SolidLintRule {
       visitor.visitIsExpression(node);
 
       for (final element in visitor.expressions.entries) {
-        reporter.reportErrorForNode(code, element.key);
+        reporter.reportErrorForNode(
+          code,
+          element.key,
+          [element.value.toString()],
+        );
       }
     });
   }

lib/src/lints/avoid_unrelated_type_assertions/avoid_unrelated_type_assertions_visitor.dart

@@ -30,25 +30,24 @@ import 'package:collection/collection.dart';
 /// AST Visitor which finds all is expressions and checks if they are
 /// unrelated (result always false)
 class AvoidUnrelatedTypeAssertionsVisitor extends RecursiveAstVisitor<void> {
-  final _expressions = <IsExpression, String>{};
+  final _expressions = <IsExpression, bool>{};
 
-  /// All is expressions
-  Map<IsExpression, String> get expressions => _expressions;
+  /// Map of unrelated type checks and their results
+  Map<IsExpression, bool> get expressions => _expressions;
 
   @override
   void visitIsExpression(IsExpression node) {
     super.visitIsExpression(node);
 
     final castedType = node.type.type;
-    if (node.notOperator != null || castedType is TypeParameterType) {
+    if (castedType is TypeParameterType) {
       return;
     }
 
     final objectType = node.expression.staticType;
 
     if (_isUnrelatedTypeCheck(objectType, castedType)) {
-      _expressions[node] =
-          '${node.isOperator.keyword?.lexeme ?? ''}${node.notOperator ?? ''}';
+      _expressions[node] = node.notOperator != null;
     }
   }
 

lint_test/avoid_unrelated_type_assertions_test.dart

@@ -1,4 +1,4 @@
-// ignore_for_file: prefer_const_declarations, prefer_match_file_name
+// ignore_for_file: prefer_const_declarations, prefer_match_file_name, unused_element
 // ignore_for_file: unnecessary_nullable_for_final_variable_declarations
 // ignore_for_file: unused_local_variable
 
@@ -31,3 +31,19 @@ void fun() {
   // expect_lint: avoid_unrelated_type_assertions
   final result5 = testMap['A'] is double;
 }
+
+class _A {}
+
+class _B extends _A {}
+
+class _C {}
+
+void lint() {
+  final _A a = _B();
+  // Always false
+  // expect_lint: avoid_unrelated_type_assertions
+  if (a is _C) return;
+  // Always true
+  // expect_lint: avoid_unrelated_type_assertions
+  if (a is! _C) return;
+}