Dart Code Linter

Dart Code Linter (DCL) is a powerful toolkit designed to enhance your development process by identifying and resolving issues within your Dart and Flutter code. Whether you're dealing with potential runtime bugs, violations of best practices, or styling concerns, DCL has got you covered. With a comprehensive collection of over 70 pre-built rules, you can effortlessly validate your code against a variety of expectations. Furthermore, DCL offers the flexibility to customize these rules to cater to your specific requirements, ensuring an optimized coding experience.

Links

• See CHANGELOG.md for major/breaking updates, and releases for a detailed version history.
• To contribute, please read CONTRIBUTING.md first.
• Please open an issue if anything is missing or unclear in this documentation.

Installation

$ dart pub add --dev dart_code_linter

# or for a Flutter package
$ flutter pub add --dev dart_code_linter

Basic configuration

Add configuration to analysis_options.yaml and reload IDE to allow the analyzer to discover the plugin config.

Basic config example

analyzer:
  plugins:
    - dart_code_linter

dart_code_linter:
  rules:
    - avoid-dynamic
    - avoid-passing-async-when-sync-expected
    - avoid-redundant-async
    - avoid-unnecessary-type-assertions
    - avoid-unnecessary-type-casts
    - avoid-unrelated-type-assertions
    - avoid-unused-parameters
    - avoid-nested-conditional-expressions
    - newline-before-return
    - no-boolean-literal-compare
    - no-empty-block
    - prefer-trailing-comma
    - prefer-conditional-expressions
    - no-equal-then-else
    - prefer-moving-to-variable
    - prefer-match-file-name

Basic config with metrics

analyzer:
  plugins:
    - dart_code_linter

dart_code_linter:
  metrics:
    cyclomatic-complexity: 20
    number-of-parameters: 4
    maximum-nesting-level: 5
  metrics-exclude:
    - test/**
  rules:
    - avoid-dynamic
    - avoid-passing-async-when-sync-expected
    - avoid-redundant-async
    - avoid-unnecessary-type-assertions
    - avoid-unnecessary-type-casts
    - avoid-unrelated-type-assertions
    - avoid-unused-parameters
    - avoid-nested-conditional-expressions
    - newline-before-return
    - no-boolean-literal-compare
    - no-empty-block
    - prefer-trailing-comma
    - prefer-conditional-expressions
    - no-equal-then-else
    - prefer-moving-to-variable
    - prefer-match-file-name

Usage

Analyzer plugin

DCL can be used as a plugin for the Dart analyzer package providing additional rules. All issues produced by rules or anti-patterns will be highlighted in IDE.

Rules that marked with 🛠 have auto-fixes available through the IDE context menu. VS Code example:

CLI

The package can be used as CLI and supports multiple commands:

Command	Example of use	Short description
analyze	dart run dart_code_linter:metrics analyze lib	Reports code metrics, rules and anti-patterns violations.
check-unnecessary-nullable	dart run dart_code_linter:metrics check-unnecessary-nullable lib	Checks unnecessary nullable parameters in functions, methods, constructors.
check-unused-files	dart run dart_code_linter:metrics check-unused-files lib	Checks unused *.dart files.
check-unused-l10n	dart run dart_code_linter:metrics check-unused-l10n lib	Check unused localization in *.dart files.
check-unused-code	dart run dart_code_linter:metrics check-unused-code lib	Checks unused code in *.dart files.

For additional help on any of the commands, enter dart run dart_code_linter:metrics help <command>

Note: if you're setting up DCL for multi-package repository (a.k.a. monorepo), it'll pick up analysis_options.yaml files correctly.

You can define one analysis_options.yaml at the root file.

Analyze

Reports code metrics, rules and anti-patterns violations. To execute the command, run

$ dart run dart_code_linter:metrics analyze lib

# or for a Flutter package
$ flutter pub run dart_code_linter:metrics analyze lib

It will produce a result in one of the format:

• Console
• GitHub
• Codeclimate
• HTML
• JSON

Check unnecessary nullable parameters

Checks unnecessary nullable parameters in functions, methods, constructors. To execute the command, run

$ dart run dart_code_linter:metrics check-unnecessary-nullable lib

# or for a Flutter package
$ flutter pub run dart_code_linter:metrics check-unnecessary-nullable lib

It will produce a result in one of the format:

• Console
• JSON

Check unused files

Checks unused *.dart files. To execute the command, run

$ dart run dart_code_linter:metrics check-unused-files lib

# or for a Flutter package
$ flutter pub run dart_code_linter:metrics check-unused-files lib

It will produce a result in one of the format:

• Console
• JSON

Check unused localization

Checks unused Dart class members, that encapsulates the app’s localized values.

An example of such class:

class ClassWithLocalization {
  String get title {
    return Intl.message(
      'Hello World',
      name: 'title',
      desc: 'Title for the Demo application',
      locale: localeName,
    );
  }
}

To execute the command, run

$ dart run dart_code_linter:metrics check-unused-l10n lib

# or for a Flutter package
$ flutter pub run dart_code_linter:metrics check-unused-l10n lib

It will produce a result in one of the format:

• Console
• JSON

Check unused code

Checks unused code in *.dart files. To execute the command, run

$ dart run dart_code_linter:metrics check-unused-code lib

# or for a Flutter package
$ flutter pub run dart_code_linter:metrics check-unused-code lib

It will produce a result in one of the format:

• Console
• JSON

Troubleshooting

Please read the following guide if the plugin is not working as you'd expect it to work.

Contributing

If you are interested in contributing, please check out the contribution guidelines. Feedback and contributions are welcome!

License

Dart Code Linter is licensed under the MIT