Cops

Style cops check for stylistic consistency of your code. Many of them are based on the Ruby Style Guide. This is the largest department and covers everything from preferred hash syntax to method naming conventions. Most Style cops support multiple EnforcedStyle options so you can adapt them to your team’s preferences.

Layout cops inspect your code for consistent use of indentation, alignment, and white space. They deal exclusively with formatting — changing Layout cops never affects program behavior. Running rubocop -x applies only Layout autocorrections.

Lint cops check for ambiguities and possible errors in your code.

RuboCop implements, in a portable way, all built-in MRI lint checks (ruby -wc) and adds a lot of extra lint checks of its own.

You can run only the Lint cops like this:

The -l/--lint option can be used together with --only to run all the enabled Lint cops plus a selection of other cops.

Disabling Lint cops is generally a bad idea.

Metrics cops deal with properties of the source code that can be measured, such as class length, method length, and cyclomatic complexity. They have a configuration parameter called Max and when running rubocop --auto-gen-config, this parameter will be set to the highest value found for the inspected code.

Naming cops check for naming issues in your code, such as method names, constant names, file names, and predicate prefixes. Like Style cops, many support multiple enforced styles.

Security cops check for method calls and constructs which are known to be associated with potential security issues, such as the use of eval or YAML.load.

Bundler cops check for style and bad practices in Bundler files, e.g. Gemfile.

Gemspec cops check for style and bad practices in gemspec files, e.g. rubocop.gemspec.