请教如何为Flutter与Dart定义自定义Linter规则

Hey there! Let's walk through how to set up linter rules for your Flutter/Dart projects, plus how to build your own custom rules when the predefined ones don't cut it. I'll keep this practical with examples you can copy-paste and tweak.

Getting started with existing rules is super straightforward—here's how:

1. Add the lint package dependency
   Flutter and Dart maintain official lint packages with curated rule sets. Add the relevant one to your pubspec.yaml under dev_dependencies:

   dev_dependencies:
     # For Flutter projects
     flutter_lints: ^2.0.0
     # For pure Dart projects
     lints: ^2.0.0
   

   Run flutter pub get or dart pub get to install it.

2. Create/modify the analysis_options.yaml file
   This file is where you'll control which rules are enabled or disabled. Start by inheriting the default rule set, then customize as needed:

   # Inherit the default Flutter lint rules
   include: package:flutter_lints/flutter.yaml
   
   linter:
     rules:
       # Enable a specific rule that's off by default
       prefer_const_constructors: true
       # Disable a rule from the default set
       avoid_print: false
       # You can also set rules with options (if supported)
       prefer_single_quotes: true
   

3. Run the linter
   Check your code manually with the command line:

   # For Flutter
   flutter analyze
   # For pure Dart
   dart analyze
   

   Most IDEs (like VS Code or Android Studio) will also show lint warnings in real-time as you code.

If you need to enforce project-specific standards (like banning certain functions or enforcing naming conventions), you can build your own rules. We'll use the custom_lint_builder package to simplify this process:

1. Set up a custom lint package
   Custom rules live in a separate Dart package (not your Flutter app). Create one with:

   dart create -t package my_custom_lints
   cd my_custom_lints
   

   Add these dependencies to pubspec.yaml:

   dependencies:
     analyzer: ^5.13.0
     custom_lint_builder: ^0.6.0
   
   dev_dependencies:
     test: ^1.24.0
     custom_lint: ^0.6.0
   

2. Write your custom rule
   Create a file lib/src/no_print_rule.dart for a rule that bans print() calls (encouraging logging libraries instead):

   import 'package:analyzer/dart/ast/ast.dart';
   import 'package:custom_lint_builder/custom_lint_builder.dart';
   
   class NoPrintRule extends DartLintRule {
     NoPrintRule() : super(
       code: const LintCode(
         name: 'no_print',
         problemMessage: 'Avoid using print()—use a logging library like logger instead.',
         correctionMessage: 'Replace print(...) with Logger().d(...) or similar.',
       ),
     );
   
     @override
     void run(
       CustomLintResolver resolver,
       ErrorReporter reporter,
       CustomLintContext context,
     ) {
       // Listen for method invocations in the code
       context.registry.addMethodInvocation((node) {
         // Check if the method is a top-level print() call
         if (node.methodName.name == 'print' && node.target == null) {
           // Report an error at the print() call location
           reporter.reportErrorForNode(code, node);
         }
       });
     }
   }
   

3. Register your rule
   Update lib/my_custom_lints.dart to register your rule with the linter plugin:

   import 'package:custom_lint_builder/custom_lint_builder.dart';
   import 'src/no_print_rule.dart';
   
   PluginBase createPlugin() => _MyCustomLints();
   
   class _MyCustomLints extends PluginBase {
     @override
     List<DartLintRule> getLintRules(CustomLintConfigs configs) => [
           NoPrintRule(),
           // Add more rules here later
         ];
   }
   

4. Use the custom rule in your project
   Go back to your Flutter/Dart project and add the custom lint package to pubspec.yaml:

   dev_dependencies:
     flutter_lints: ^2.0.0
     my_custom_lints:
       path: ../my_custom_lints # Use path if local, or pub.dev package name if published
   

   Then update analysis_options.yaml to enable the rule:

   include: package:flutter_lints/flutter.yaml
   
   linter:
     rules:
       my_custom_lints/no_print: true
   

   Run flutter analyze—you'll now see warnings wherever print() is used!

5. Test your rule
   Write tests to make sure your rule works as expected. Create test/no_print_rule_test.dart:

   import 'package:custom_lint_test/custom_lint_test.dart';
   import 'package:test/test.dart';
   
   void main() {
     test('Detects print() calls', () async {
       await resolveSource('''
         void main() {
           print('hello'); // LINT
         }
       ''').expectLints(['no_print']);
     });
   
     test('Ignores print() from a class', () async {
       await resolveSource('''
         class Logger {
           void print(String msg) {}
         }
   
         void main() {
           Logger().print('hello'); // NO LINT
         }
       ''').expectNoLints();
     });
   }
   

   Run tests with dart test.

内容的提问来源于stack exchange，提问作者Hamed Rezaee