feat: add avoid-substring rule (#1206)

Author: lsaudon

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 * feat: add static code diagnostic [prefer-define-hero-tag](https://github.com/dart-code-checker/dart-code-metrics/issues/1027).
 * chore: restrict `analyzer` version to `>=5.1.0 <5.8.0`.
+* feat: add avoid-substring rule
 
 ## 5.6.0
 

lib/src/analyzers/lint_analyzer/rules/rules_factory.dart

@@ -24,6 +24,7 @@ import 'rules_list/avoid_redundant_async/avoid_redundant_async_rule.dart';
 import 'rules_list/avoid_redundant_async_on_load/avoid_redundant_async_on_load_rule.dart';
 import 'rules_list/avoid_returning_widgets/avoid_returning_widgets_rule.dart';
 import 'rules_list/avoid_shrink_wrap_in_lists/avoid_shrink_wrap_in_lists_rule.dart';
+import 'rules_list/avoid_substring/avoid_substring_rule.dart';
 import 'rules_list/avoid_throw_in_catch_block/avoid_throw_in_catch_block_rule.dart';
 import 'rules_list/avoid_top_level_members_in_tests/avoid_top_level_members_in_tests_rule.dart';
 import 'rules_list/avoid_unnecessary_conditionals/avoid_unnecessary_conditionals_rule.dart';
@@ -108,6 +109,7 @@ final _implementedRules = <String, Rule Function(Map<String, Object>)>{
   AvoidRedundantAsyncOnLoadRule.ruleId: AvoidRedundantAsyncOnLoadRule.new,
   AvoidReturningWidgetsRule.ruleId: AvoidReturningWidgetsRule.new,
   AvoidShrinkWrapInListsRule.ruleId: AvoidShrinkWrapInListsRule.new,
+  AvoidSubstringRule.ruleId: AvoidSubstringRule.new,
   AvoidThrowInCatchBlockRule.ruleId: AvoidThrowInCatchBlockRule.new,
   AvoidTopLevelMembersInTestsRule.ruleId: AvoidTopLevelMembersInTestsRule.new,
   AvoidUnnecessaryConditionalsRule.ruleId: AvoidUnnecessaryConditionalsRule.new,

lib/src/analyzers/lint_analyzer/rules/rules_list/avoid_substring/avoid_substring_rule.dart

@@ -0,0 +1,47 @@
+// ignore_for_file: public_member_api_docs
+
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/visitor.dart';
+
+import '../../../../../utils/node_utils.dart';
+import '../../../lint_utils.dart';
+import '../../../models/internal_resolved_unit_result.dart';
+import '../../../models/issue.dart';
+import '../../../models/severity.dart';
+import '../../models/common_rule.dart';
+import '../../rule_utils.dart';
+
+part 'visitor.dart';
+
+class AvoidSubstringRule extends CommonRule {
+  static const String ruleId = 'avoid-substring';
+
+  static const _warning =
+      'Avoid using substring if you are having emojis in the string. Consider using characters.getRange instead.';
+
+  AvoidSubstringRule([Map<String, Object> config = const {}])
+      : super(
+          id: ruleId,
+          severity: readSeverity(config, Severity.warning),
+          excludes: readExcludes(config),
+          includes: readIncludes(config),
+        );
+
+  @override
+  Iterable<Issue> check(InternalResolvedUnitResult source) {
+    final visitor = _Visitor();
+
+    source.unit.visitChildren(visitor);
+
+    return visitor.expressions
+        .map((expression) => createIssue(
+              rule: this,
+              location: nodeLocation(
+                node: expression,
+                source: source,
+              ),
+              message: _warning,
+            ))
+        .toList(growable: false);
+  }
+}

lib/src/analyzers/lint_analyzer/rules/rules_list/avoid_substring/visitor.dart

@@ -0,0 +1,19 @@
+part of 'avoid_substring_rule.dart';
+
+class _Visitor extends RecursiveAstVisitor<void> {
+  final _expressions = <Expression>[];
+
+  Iterable<Expression> get expressions => _expressions;
+
+  @override
+  void visitMethodInvocation(MethodInvocation node) {
+    super.visitMethodInvocation(node);
+    if (_isNotSubstringMethod(node)) {
+      return;
+    }
+    _expressions.add(node);
+  }
+
+  bool _isNotSubstringMethod(MethodInvocation node) =>
+      node.methodName.name != 'substring';
+}

test/src/analyzers/lint_analyzer/rules/rules_list/avoid_substring/avoid_substring_rule_test.dart

@@ -0,0 +1,41 @@
+import 'package:dart_code_metrics/src/analyzers/lint_analyzer/models/severity.dart';
+import 'package:dart_code_metrics/src/analyzers/lint_analyzer/rules/rules_list/avoid_substring/avoid_substring_rule.dart';
+import 'package:test/test.dart';
+
+import '../../../../../helpers/rule_test_helper.dart';
+
+const _examplePath = 'avoid_substring/examples/example.dart';
+
+void main() {
+  group('AvoidSubstringRule', () {
+    test('initialization', () async {
+      final unit = await RuleTestHelper.resolveFromFile(_examplePath);
+      final issues = AvoidSubstringRule().check(unit);
+
+      RuleTestHelper.verifyInitialization(
+        issues: issues,
+        ruleId: 'avoid-substring',
+        severity: Severity.warning,
+      );
+    });
+
+    test('reports about found issues', () async {
+      final unit = await RuleTestHelper.resolveFromFile(_examplePath);
+      final issues = AvoidSubstringRule().check(unit);
+
+      RuleTestHelper.verifyIssues(
+        issues: issues,
+        startLines: [3, 5],
+        startColumns: [3, 3],
+        locationTexts: [
+          's.substring(14, 15)',
+          '''"It's a smiley 😀 smile".substring(14, 15)''',
+        ],
+        messages: [
+          'Avoid using substring if you are having emojis in the string. Consider using characters.getRange instead.',
+          'Avoid using substring if you are having emojis in the string. Consider using characters.getRange instead.',
+        ],
+      );
+    });
+  });
+}

test/src/analyzers/lint_analyzer/rules/rules_list/avoid_substring/examples/example.dart

@@ -0,0 +1,6 @@
+void main() {
+  final s = "It's a smiley 😀 smile";
+  s.substring(14, 15); // LINT
+
+  "It's a smiley 😀 smile".substring(14, 15); // LINT
+}