Prefer matching widget file name (#410)

Author: vlkonoshenko

README.md

@@ -349,6 +349,7 @@ Rules configuration is [described here](#configuring-a-rules-entry).
 - [no-magic-number](https://github.com/dart-code-checker/dart-code-metrics/blob/master/doc/rules/no-magic-number.md)   [![Configurable](https://img.shields.io/badge/-configurable-informational)](https://github.com/dart-code-checker/dart-code-metrics/blob/master/doc/rules/no-magic-number.md#config-example)
 - [no-object-declaration](https://github.com/dart-code-checker/dart-code-metrics/blob/master/doc/rules/no-object-declaration.md)
 - [prefer-conditional-expressions](https://github.com/dart-code-checker/dart-code-metrics/blob/master/doc/rules/prefer-conditional-expressions.md)   ![Has auto-fix](https://img.shields.io/badge/-has%20auto--fix-success)
+- [prefer-match-file-name](https://github.com/dart-code-checker/dart-code-metrics/blob/master/doc/rules/prefer-match-file-name.md)
 - [prefer-trailing-comma](https://github.com/dart-code-checker/dart-code-metrics/blob/master/doc/rules/prefer-trailing-comma.md)   [![Configurable](https://img.shields.io/badge/-configurable-informational)](https://github.com/dart-code-checker/dart-code-metrics/blob/master/doc/rules/prefer-trailing-comma.md#config-example)   ![Has auto-fix](https://img.shields.io/badge/-has%20auto--fix-success)
 
 ### Flutter specific

doc/rules/prefer-match-file-name.md

@@ -0,0 +1,97 @@
+# Prefer match file name
+
+## Rule id
+
+prefer-match-file-name
+
+## Description
+
+Warns if the file name does not match the name of the first public class in the file or a private class if there are no
+public classes.
+
+### Config example
+
+We recommend exclude the `test` folder.
+
+```yaml
+dart_code_metrics:
+  ...
+  rules:
+    ...
+    - prefer-match-file-name:
+        exclude:
+          - test/**
+    ...
+```
+
+### Example
+
+#### Example 1 One class in the file
+
+Bad:
+
+File name: **some_widget.dart**
+
+```dart
+class SomeOtherWidget extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    //...
+  }
+}
+```
+
+Good:
+
+File name: **some_widget.dart**
+
+```dart
+class SomeWidget extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    //...
+  }
+}
+```
+
+#### Example 2 Multiple class in the file
+
+Bad:
+
+File name: **some_other_widget.dart**
+
+```dart
+class _SomeOtherWidget extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    //...
+  }
+}
+
+class SomeWidget extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    //...
+  }
+}
+```
+
+Good:
+
+File name: **some_widget.dart**
+
+```dart
+class _SomeOtherWidget extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    //...
+  }
+}
+
+class SomeWidget extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    //...
+  }
+}
+```

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

@@ -22,6 +22,7 @@ import 'rules_list/no_object_declaration/no_object_declaration.dart';
 import 'rules_list/prefer_conditional_expressions/prefer_conditional_expressions.dart';
 import 'rules_list/prefer_extracting_callbacks/prefer_extracting_callbacks.dart';
 import 'rules_list/prefer_intl_name/prefer_intl_name.dart';
+import 'rules_list/prefer_match_file_name/prefer_match_file_name.dart';
 import 'rules_list/prefer_on_push_cd_strategy/prefer_on_push_cd_strategy.dart';
 import 'rules_list/prefer_single_widget_per_file/prefer_single_widget_per_file.dart';
 import 'rules_list/prefer_trailing_comma/prefer_trailing_comma.dart';
@@ -63,6 +64,7 @@ final _implementedRules = <String, Rule Function(Map<String, Object>)>{
   PreferExtractingCallbacksRule.ruleId: (config) =>
       PreferExtractingCallbacksRule(config),
   PreferIntlNameRule.ruleId: (config) => PreferIntlNameRule(config),
+  PreferMatchFileName.ruleId: (config) => PreferMatchFileName(config),
   PreferOnPushCdStrategyRule.ruleId: (config) =>
       PreferOnPushCdStrategyRule(config),
   PreferSingleWidgetPerFileRule.ruleId: (config) =>

lib/src/analyzers/lint_analyzer/rules/rules_list/prefer_match_file_name/prefer_match_file_name.dart

@@ -0,0 +1,66 @@
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/visitor.dart';
+import 'package:path/path.dart';
+
+import '../../../../../utils/node_utils.dart';
+import '../../../models/internal_resolved_unit_result.dart';
+import '../../../models/issue.dart';
+import '../../../models/severity.dart';
+import '../../models/rule.dart';
+import '../../models/rule_documentation.dart';
+import '../../rule_utils.dart';
+
+part 'visitor.dart';
+
+class PreferMatchFileName extends Rule {
+  static const String ruleId = 'prefer-match-file-name';
+  static const _notMatchNameFailure =
+      'File name does not match with first class name';
+  static final _onlySymbolsRegex = RegExp('[^a-zA-Z0-9]');
+
+  PreferMatchFileName([Map<String, Object> config = const {}])
+      : super(
+          id: ruleId,
+          documentation: const RuleDocumentation(
+            name: 'Prefer match file name',
+            brief: 'Warns when file name does not match class name.',
+          ),
+          severity: readSeverity(config, Severity.warning),
+          excludes: readExcludes(config),
+        );
+
+  bool _hasMatchName(String path, String className) {
+    final classNameFormatted =
+        className.replaceAll(_onlySymbolsRegex, '').toLowerCase();
+
+    return classNameFormatted ==
+        basenameWithoutExtension(path)
+            .replaceAll(_onlySymbolsRegex, '')
+            .toLowerCase();
+  }
+
+  @override
+  Iterable<Issue> check(InternalResolvedUnitResult source) {
+    final visitor = _Visitor();
+    source.unit.visitChildren(visitor);
+
+    final _issue = <Issue>[];
+
+    if (visitor.declaration.isNotEmpty &&
+        !_hasMatchName(source.path, visitor.declaration.first.name)) {
+      final issue = createIssue(
+        rule: this,
+        location: nodeLocation(
+          node: visitor.declaration.first,
+          source: source,
+          withCommentOrMetadata: true,
+        ),
+        message: _notMatchNameFailure,
+      );
+
+      _issue.add(issue);
+    }
+
+    return _issue;
+  }
+}

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

@@ -0,0 +1,27 @@
+part of 'prefer_match_file_name.dart';
+
+class _Visitor extends RecursiveAstVisitor<void> {
+  final _declarations = <SimpleIdentifier>[];
+
+  Iterable<SimpleIdentifier> get declaration =>
+      _declarations..sort(_compareByPrivateType);
+
+  @override
+  void visitClassDeclaration(ClassDeclaration node) {
+    super.visitClassDeclaration(node);
+
+    _declarations.add(node.name);
+  }
+
+  int _compareByPrivateType(SimpleIdentifier a, SimpleIdentifier b) {
+    final isAPrivate = Identifier.isPrivateName(a.name);
+    final isBPrivate = Identifier.isPrivateName(b.name);
+    if (!isAPrivate && isBPrivate) {
+      return -1;
+    } else if (isAPrivate && !isBPrivate) {
+      return 1;
+    }
+
+    return a.offset.compareTo(b.offset);
+  }
+}

test/analyzers/lint_analyzer/rules/rules_list/prefer_match_file_name/examples/empty_file.dart

@@ -0,0 +1 @@
+

test/analyzers/lint_analyzer/rules/rules_list/prefer_match_file_name/examples/example.dart

@@ -0,0 +1,8 @@
+class Example extends StatelessWidget {
+  const Example({Key? key}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return Container();
+  }
+}

test/analyzers/lint_analyzer/rules/rules_list/prefer_match_file_name/examples/example_with_issue.dart

@@ -0,0 +1,8 @@
+class Example extends StatelessWidget {
+  const Example({Key? key}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return Container();
+  }
+}

test/analyzers/lint_analyzer/rules/rules_list/prefer_match_file_name/examples/example_with_state.dart

@@ -0,0 +1,13 @@
+class ExampleWithState extends StatefulWidget {
+  const ExampleWithState({Key? key}) : super(key: key);
+
+  @override
+  _ExampleWithStateState createState() => _ExampleWithStateState();
+}
+
+class _ExampleWithStateState extends State<ExampleWithState> {
+  @override
+  Widget build(BuildContext context) {
+    return Container();
+  }
+}

test/analyzers/lint_analyzer/rules/rules_list/prefer_match_file_name/examples/multiple_classes_example.dart

@@ -0,0 +1,9 @@
+class _Multiclass {}
+
+class MultipleClassesExample {}
+
+class Test {}
+
+class Absolut {}
+
+class Best {}