Some of the information here is forward looking, as RuboCop 1.0 is still not released.

RuboCop is stable between major versions, both in terms of API and cop configuration.

Release Policy

We’re following Semantic Versioning (as much as one can be following it when the major version is 0). At this point bumps of the minor (second) version number are considered major releases and always include new features or significant changes to existing features. API compatibility between major releases is a big concern, as there are many RuboCop extensions that can be affected by breaking API changes.

The development cycle for the next major release starts immediately after the previous one has been shipped. Bugfix/point releases (if any) address only serious bugs and never contain new features.

Here are a few examples:

  • 0.50.0 - Feature release

  • 0.50.1 - Bug-fix release

  • 0.50.2 - Bug-fix release

  • 0.51.0 - Feature release

Pending Cops

In the early versions of RuboCop a common source of frustration was that new cops were added to pretty much every release, and as they were enabled by default, every upgrade resulted in broken CI builds and trying to figure out what exactly was changed. After considering many options to address this eventually we opted for an approach that limits these type of changes to major RuboCop releases.

Now new cops introduced between major versions are set to a special pending status and are not enabled by default. A warning is emitted if such cops are not explicitly enabled or disabled in the user configuration. Here’s one such message:

The following cops were added to RuboCop, but are not configured. Please
set Enabled to either `true` or `false` in your `.rubocop.yml` file:
 - Style/HashEachMethods (0.80)
 - Style/HashTransformKeys (0.80)
 - Style/HashTransformValues (0.80)
For more information:

You can see that 3 new cops were added in RuboCop 0.80 and it’s up to you to decide if you want to enable or disable them.

To suppress this message set NewCops to either enable or disable in your .rubocop.yml file.

The following setting or using rubocop --enable-pending-cops command-line option, pending cops are enabled in bulk.

  NewCops: enable

The following setting or using rubocop --disable-pending-cops command-line option, pending cops are disabled in bulk.

  NewCops: disable

The command-line options takes precedence over .rubocop.yml file.

Or set Enabled to either true or false in your .rubocop.yml file.

Style/ANewCop is an example of a newly added pending cop:

  Enabled: true


  Enabled: false

On major version updates, pending cops are enabled in bulk.