Add new Rails/Inquiry cop

CHANGELOG.md

@@ -10,6 +10,7 @@
 * [#271](https://github.com/rubocop-hq/rubocop-rails/pull/271): Add new `Rails/RenderInline` cop. ([@fatkodima][])
 * [#281](https://github.com/rubocop-hq/rubocop-rails/pull/281): Add new `Rails/MailerName` cop. ([@fatkodima][])
 * [#280](https://github.com/rubocop-hq/rubocop-rails/pull/280): Add new `Rails/ShortI18n` cop. ([@fatkodima][])
+* [#282](https://github.com/rubocop-hq/rubocop-rails/pull/282): Add new `Rails/Inquiry` cop. ([@fatkodima][])
 * [#246](https://github.com/rubocop-hq/rubocop-rails/issues/246): Add new `Rails/PluckInWhere` cop. ([@fatkodima][])
 * [#17](https://github.com/rubocop-hq/rubocop-rails/issues/17): Add new `Rails/NegateInclude` cop. ([@fatkodima][])
 * [#278](https://github.com/rubocop-hq/rubocop-rails/pull/278): Add new `Rails/Pluck` cop. ([@eugeneius][])

config/default.yml

@@ -308,6 +308,12 @@ Rails/IndexWith:
   Enabled: true
   VersionAdded: '2.5'
 
+Rails/Inquiry:
+  Description: "Prefer Ruby's comparison operators over Active Support's `Array#inquiry` and `String#inquiry`."
+  StyleGuide: 'https://rails.rubystyle.guide/#inquiry'
+  Enabled: 'pending'
+  VersionAdded: '2.7'
+
 Rails/InverseOf:
   Description: 'Checks for associations where the inverse cannot be determined automatically.'
   Enabled: true

docs/modules/ROOT/pages/cops.adoc

@@ -36,6 +36,7 @@
 * xref:cops_rails.adoc#railsignoredskipactionfilteroption[Rails/IgnoredSkipActionFilterOption]
 * xref:cops_rails.adoc#railsindexby[Rails/IndexBy]
 * xref:cops_rails.adoc#railsindexwith[Rails/IndexWith]
+* xref:cops_rails.adoc#railsinquiry[Rails/Inquiry]
 * xref:cops_rails.adoc#railsinverseof[Rails/InverseOf]
 * xref:cops_rails.adoc#railslexicallyscopedactionfilter[Rails/LexicallyScopedActionFilter]
 * xref:cops_rails.adoc#railslinktoblank[Rails/LinkToBlank]

docs/modules/ROOT/pages/cops_rails.adoc

@@ -1618,6 +1618,45 @@ Hash[[1, 2, 3].collect { |el| [el, foo(el)] }]
 [1, 2, 3].index_with { |el| foo(el) }
 ----
 
+== Rails/Inquiry
+
+|===
+| Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged
+
+| Pending
+| Yes
+| No
+| 2.7
+| -
+|===
+
+This cop checks that Active Support's `inquiry` method is not used.
+
+=== Examples
+
+[source,ruby]
+----
+# bad - String#inquiry
+ruby = 'two'.inquiry
+ruby.two?
+
+# good
+ruby = 'two'
+ruby == 'two'
+
+# bad - Array#inquiry
+pets = %w(cat dog).inquiry
+pets.gopher?
+
+# good
+pets = %w(cat dog)
+pets.include? 'cat'
+----
+
+=== References
+
+* https://rails.rubystyle.guide/#inquiry
+
 == Rails/InverseOf
 
 |===

lib/rubocop/cop/rails/inquiry.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Rails
+      # This cop checks that Active Support's `inquiry` method is not used.
+      #
+      # @example
+      #   # bad - String#inquiry
+      #   ruby = 'two'.inquiry
+      #   ruby.two?
+      #
+      #   # good
+      #   ruby = 'two'
+      #   ruby == 'two'
+      #
+      #   # bad - Array#inquiry
+      #   pets = %w(cat dog).inquiry
+      #   pets.gopher?
+      #
+      #   # good
+      #   pets = %w(cat dog)
+      #   pets.include? 'cat'
+      #
+      class Inquiry < Cop
+        MSG = "Prefer Ruby's comparison operators over Active Support's `inquiry`."
+
+        def on_send(node)
+          add_offense(node, location: :selector) if node.method?(:inquiry) && node.arguments.empty?
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/rails_cops.rb

@@ -38,6 +38,7 @@
 require_relative 'rails/ignored_skip_action_filter_option'
 require_relative 'rails/index_by'
 require_relative 'rails/index_with'
+require_relative 'rails/inquiry'
 require_relative 'rails/inverse_of'
 require_relative 'rails/lexically_scoped_action_filter'
 require_relative 'rails/link_to_blank'

spec/rubocop/cop/rails/inquiry_spec.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::Rails::Inquiry do
+  subject(:cop) { described_class.new }
+
+  it 'registers an offense when using `#inquiry`' do
+    expect_offense(<<~RUBY)
+      'two'.inquiry
+            ^^^^^^^ Prefer Ruby's comparison operators over Active Support's `inquiry`.
+    RUBY
+  end
+
+  it 'does not register an offense when using `#inquiry` with arguments' do
+    expect_no_offenses(<<~RUBY)
+      foo.inquiry(bar)
+    RUBY
+  end
+end