Extensions
It’s possible to extend RuboCop with custom cops and formatters.
Loading Extensions
Besides the --require command line option you can also specify ruby
files that should be loaded with the optional require directive in the
.rubocop.yml file:
require:
- ../my/custom/file.rb
- rubocop-extension
The paths are directly passed to Kernel.require. If your
extension file is not in $LOAD_PATH, you need to specify the path as
relative path prefixed with ./ explicitly or absolute path. Paths
starting with a . are resolved relative to .rubocop.yml.
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Custom Cops
You can configure the custom cops in your .rubocop.yml just like any
other cop.
Writing your own Cops
If you’d like to create an extension gem, you can use rubocop-extension-generator.
See development to learn how to implement a cop.
Known Custom Cops
-
rubocop-performance - Performance optimization analysis
-
rubocop-rails - Rails-specific analysis
-
rubocop-rspec - RSpec-specific analysis
-
rubocop-minitest - Minitest-specific analysis
-
rubocop-thread_safety - Thread-safety analysis
-
rubocop-require_tools - Dynamic analysis for missing require statements
-
rubocop-i18n - i18n wrapper function analysis (gettext and rails-i18n)
-
rubocop-sequel - Code style checking for Sequel gem
-
cookstyle - Custom cops and config defaults for Chef Infra Cookbooks
-
rubocop-rake - Rake-specific analysis
-
rubocop-packaging - Upstream best practices and coding conventions for downstream compatibility.
Any extensions missing? Send us a Pull Request!
Custom Formatters
You can customize RuboCop’s output format with custom formatters.
Creating a Custom Formatter
To implement a custom formatter, you need to subclass
RuboCop::Formatter::BaseFormatter and override some methods,
or implement all formatter API methods by duck typing.
Please see the documents below for more formatter API details.
Using a Custom Formatter from the Command Line
You can tell RuboCop to use your custom formatter with a combination of
--format and --require option.
For example, when you have defined MyCustomFormatter in
./path/to/my_custom_formatter.rb, you would type this command:
$ rubocop --require ./path/to/my_custom_formatter --format MyCustomFormatter