Cop idea: Suggest using validate option for enums since Rails 7.1

[ybiquitous]

Is your feature request related to a problem? Please describe.

Rails 7.1 has added the support Enum validation implemented by PR rails/rails#49100. For example:

class Contract < ApplicationRecord
  enum :status, [:in_progress, :completed], validate: true
end

As we can see many positive reactions in rails/rails#49100, many people seem to love the feature. So, I think it's worth adding a new cop to suggest using the validate option for enums.

Describe the solution you'd like

The new cop would suggest validate as below if enabled:

class User < ActiveRecord::Base
  # bad
  enum :status, [:enabled, :disabled]
# ^^^^ Prefer the `:validate` option over `ArgumentError`.

  # good
  enum :activity, [:active, :inactive], validate: true
end

But first, I believe this cop should be disabled by default because the code's behavior would change. We could enable the cop by default when many people are familiar with this feature (I hope this cop can help that 😁).

Describe alternatives you've considered

I have no alternatives for now.

Additional context

Here is a reproduction of this feature, although it's a bit too long: ⬇️

Reproduction code

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  gem "rails", "~> 7.1"
  gem "sqlite3", "~> 1.7"
end

require "active_record"
require "minitest/autorun"
require "logger"

ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
ActiveRecord::Base.logger = Logger.new(STDOUT)

ActiveRecord::Schema.define do
  create_table :users, force: true do |t|
    t.column :status, :integer
    t.column :activity, :integer
  end
end

class User < ActiveRecord::Base
  # bad (< Rails 7.1)
  enum :status, [:enabled, :disabled]

  # good (>= Rails 7.1)
  enum :activity, [:active, :inactive], validate: true
end

class UserTest < Minitest::Test
  def setup
    @user = User.new
  end

  def test_status
    assert_raises(ArgumentError, "'foo' is not a valid status") do
      @user.status = :foo
    end
  end

  def test_activity
    @user.activity = :foo
    refute @user.valid?
    assert_equal ["Activity is not included in the list"], @user.errors.full_messages

    @user.activity = :active
    assert @user.valid?
  end
end

If you have Docker, you can save this code to test.rb in any directory and run it easily:

docker run --rm -it -v ${PWD}:/work -w /work ruby:3.3 ruby test.rb

Thanks for reading.

[yykamei]

But first, I believe this cop should be disabled by default because the code's behavior would change.

I support this idea. The Cop is definitely useful, but this Cop might suggest the code below:

class Attend < ActiveRecord::Base
  enum size: [:yes, :no, :maybe]

  validates :size, inclusion: { in: sizes.keys }
end

Borrowed from https://stackoverflow.com/questions/8146965/how-do-i-specify-and-validate-an-enum-in-rails

If this Cop suggest in the code, developers might feel false-positive.

That's why it's great to make the Cop disabled by default 👍