RuboCop

RuboCop is a Ruby code style checker based on the Ruby Style Guide.

Installation

RuboCop's installation is pretty standard:

$ gem install rubocop

Basic Usage

Running rubocop with no arguments will check all Ruby source files in the current folder:

$ rubocop

Alternatively you can rubocop a list of files and folders to check:

$ rubocop app spec lib/something.rb

For more details check the available command-line options:

$ rubocop -h

Command flag	Description
`-v/--version`	Displays the current version and exits
`-d/--debug`	Displays some extra debug output
`-e/--emacs`	Output the results in Emacs format
`-c/--config`	Run with specified config file
`-s/--silent`	Suppress the final summary

Configuration

The behavior of RuboCop can be controlled via the .rubocop.yml configuration file. The file can be placed either in your home folder or in some project folder.

RuboCop will start looking for the configuration file in the directory it was started in and continue its way up to the home folder.

The file has the following format:

Encoding:
  Enabled: true

LineLength:
  Enabled: true
  Max: 79

It allows to enable/disable certain cops (checks) and to alter their behavior if they accept any parameters.

Compatibility

Unfortunately every major Ruby implementation has its own code analysis tooling, which makes the development of a portable code analyzer a daunting task.

RuboCop currently supports MRI 1.9 and MRI 2.0. Support for JRuby and Rubinius is not planned at this point.

Editor integration

Emacs

rubocop.el is a simple Emacs interface for RuboCop. It allows you to run RuboCop inside Emacs and quickly jump between problems in your code.