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Mry Migrates .Rubocop.Yml 💪

RuboCop has many many breaking changes, because it is before version 1.0. So, if you update your RuboCop version, .rubocop.yml breaks in many cases... This tool supports migrating .rubocop.yml. It automatically renames the configuration in your .rubocop.yml that was renamed by the updated RuboCop version. So, with this tool, you do not have to be afraid of updating RuboCop anymore!


Add this line to your application's Gemfile:

gem 'mry'

And then execute:

$ bundle

Or install it yourself as:

$ gem install mry


Update .rubocop.yml to latest release:

$ mry .rubocop.yml

Update .rubocop.yml to a specified version:

$ mry --target=0.51.0 .rubocop.yml

And you can specify the current RuboCop version. If you specify a new RuboCop version, mry adds cops that were added in this new RuboCop version to your .rubocop.yml. With this feature, you can check new RuboCop cops with mry.

$ mry --from=0.50.0 --target=0.51.0 .rubocop.yml
$ cat .rubocop.yml

# The following cops are added between 0.50.0 and 0.51.0.
# The configurations are default.
# If you want to use a cop by default, remove a configuration for the cop from here.
# If you want to disable a cop, change `Enabled` to false.

# Supports --auto-correct
  Description: Dependencies in the gemspec should be alphabetically sorted.
  Enabled: true
  - "**/*.gemspec"
  TreatCommentsAsGroupSeparators: true

# Supports --auto-correct
  Description: Checks for redundant `with_object`.
  Enabled: true



Example Animation


How to support new version RuboCop

Run bin/check_rubocop_update script (depend on Ruby 2.6 or higher). This script displays renamed, added and deleted cop names.

# Clone rubocop repository if it does not exist.
$ git clone ~/path/to/rubocop/
$ bin/check_rubocop_update v0.55.0 v0.56.0 ~/path/to/rubocop/


- Lint/SplatKeywordArguments
- Performance/InefficientHashSearch
- Lint/ErbNewArguments
- Rails/AssertNot
- Rails/RefuteMethods
- :before:
  - Style/EmptyLineAfterGuardClause
  - Layout/EmptyLineAfterGuardClause
- :before:
  - Style/MethodMissing
  - Style/MethodMissingSuper
  - Style/MissingRespondToMissing
:deleted: []

Update lib/mry/added_cops.rb and lib/mry/rewriters.rb with this result.

Note: Mry does not support deleted cops and split cops. See #37 and #38.


Bug reports and pull requests are welcome on GitHub at


Copyright 2017-2018 Masataka Pocke Kuwabara

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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