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Dart Code Metrics

Note: you can find the full documentation on the website

Configuration | Rules | Metrics | Anti-patterns

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

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.

Highlighted issue example

Rules that marked with a has auto-fix badge have auto-fixes available through the IDE context menu. VS Code example:

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:

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:

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:

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:

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:

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!

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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