Dart Code Metrics

Note: you can find the full documentation on the website

Configuration | Rules | Metrics | Anti-patterns

Dart Code Metrics is a static analysis tool that helps you analyse and improve your code quality.

• Reports code metrics
• Provides additional rules for the dart analyzer
• Checks for anti-patterns
• Checks unused *.dart files
• Checks unused l10n
• Checks unnecessary nullable parameters
• Can be used as CLI, analyzer plugin or library

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_metrics

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

OR

add it manually to pubspec.yaml

dev_dependencies:
  dart_code_metrics: ^4.21.3

and then run

$ dart pub get

# or for a Flutter package
$ flutter pub get

Basic configuration

Add configuration to analysis_options.yaml

dart_code_metrics:
  anti-patterns:
    - long-method
    - long-parameter-list
  metrics:
    cyclomatic-complexity: 20
    maximum-nesting-level: 5
    number-of-parameters: 4
    source-lines-of-code: 50
  metrics-exclude:
    - test/**
  rules:
    - newline-before-return
    - no-boolean-literal-compare
    - no-empty-block
    - prefer-trailing-comma
    - prefer-conditional-expressions
    - no-equal-then-else

Reload IDE to allow the analyzer to discover the plugin config.

You can read more about the configuration on the website.

Usage

Analyzer plugin

Dart Code Metrics 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 a has auto-fix badge 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_metrics:metrics analyze lib	Reports code metrics, rules and anti-patterns violations.
check-unnecessary-nullable	dart run dart_code_metrics:metrics check-unnecessary-nullable lib	Checks unnecessary nullable parameters in functions, methods, constructors.
check-unused-files	dart run dart_code_metrics:metrics check-unused-files lib	Checks unused *.dart files.
check-unused-l10n	dart run dart_code_metrics:metrics check-unused-l10n lib	Check unused localization in *.dart files.
check-unused-code	dart run dart_code_metrics:metrics check-unused-code lib	Checks unused code in *.dart files.

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

Note: if you're setting up Dart Code Metrics for multi-package repository, check out this website section.

Analyze

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

$ dart run dart_code_metrics:metrics analyze lib

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

It will produce a result in one of the format:

• Console
• GitHub
• Codeclimate
• HTML
• JSON

Console report example:

Check unnecessary nullable parameters

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

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

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

It will produce a result in one of the format:

• Console
• JSON

Console report example:

Check unused files

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

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

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

It will produce a result in one of the format:

• Console
• JSON

Console report example:

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_metrics:metrics check-unused-l10n lib

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

It will produce a result in one of the format:

• Console
• JSON

Console report example:

Check unused code

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

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

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

It will produce a result in one of the format:

• Console
• JSON

Console report example:

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!

Articles

En

• Finding Unused Files With Dart Code Metrics - This article considers one of the first commands, checking unused Dart files, by Dmitry Zhifarsky
• Improving Code Quality With Dart Code Metrics - Advantages of using Dart Code Metrics, by Dmitry Zhifarsky
• Creating a Custom Plugin for Dart Analyzer - How to develop a custom Dart code analyzer plugin, by Dmitry Zhifarsky
• Flutter Static Analysis, Dart Code Metrics - How to install the dart_code-metrics plugin and effectively use it to analyze dart code, by Fred Grott

Ru

• Повышаем качество кода с Dart Code Metrics - Преимущества использования Dart Code Metrics, от Dmitry Zhifarsky
• Как создать кастомный плагин для Dart-анализатора - Описан процесс создания плагина для анализатора кода, от Dmitry Zhifarsky
• Dart Code Metrics — мой первый pull request - Инструкция по созданию нового правила, от Vlad Konoshenko

How to reach us

Please feel free to ask any questions about this tool. Join our community chat on Telegram. We speak both English and Russian.

LICENSE

MIT