Add new Rails/ShortI18n cop

CHANGELOG.md

@@ -9,6 +9,7 @@
 * [#275](https://github.com/rubocop-hq/rubocop-rails/pull/275): Add new `Rails/MatchRoute` cop. ([@fatkodima][])
 * [#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][])
 * [#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

@@ -558,6 +558,16 @@ Rails/ScopeArgs:
   Include:
     - app/models/**/*.rb
 
+Rails/ShortI18n:
+  Description: 'Use the short form of the I18n methods: `t` instead of `translate` and `l` instead of `localize`.'
+  StyleGuide: 'https://rails.rubystyle.guide/#short-i18n'
+  Enabled: 'pending'
+  VersionAdded: '2.7'
+  EnforcedStyle: conservative
+  SupportedStyles:
+    - conservative
+    - aggressive
+
 Rails/SkipsModelValidations:
   Description: >-
                  Use methods that skips model validations with caution.

docs/modules/ROOT/pages/cops.adoc

@@ -67,6 +67,7 @@
 * xref:cops_rails.adoc#railssafenavigationwithblank[Rails/SafeNavigationWithBlank]
 * xref:cops_rails.adoc#railssavebang[Rails/SaveBang]
 * xref:cops_rails.adoc#railsscopeargs[Rails/ScopeArgs]
+* xref:cops_rails.adoc#railsshorti18n[Rails/ShortI18n]
 * xref:cops_rails.adoc#railsskipsmodelvalidations[Rails/SkipsModelValidations]
 * xref:cops_rails.adoc#railstimezone[Rails/TimeZone]
 * xref:cops_rails.adoc#railsuniqbeforepluck[Rails/UniqBeforePluck]

docs/modules/ROOT/pages/cops_rails.adoc

@@ -3458,6 +3458,79 @@ scope :something, -> { where(something: true) }
 | Array
 |===
 
+== Rails/ShortI18n
+
+|===
+| Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged
+
+| Pending
+| Yes
+| Yes
+| 2.7
+| -
+|===
+
+This cop enforces that short forms of `I18n` methods are used:
+`t` instead of `translate` and `l` instead of `localize`.
+
+This cop has two different enforcement modes. When the EnforcedStyle
+is conservative (the default) then only `I18n.translate` and `I18n.localize`
+calls are added as offenses.
+
+When the EnforcedStyle is aggressive then all `translate` and `localize` calls
+without a receiver are added as offenses.
+
+=== Examples
+
+[source,ruby]
+----
+# bad
+I18n.translate :key
+I18n.localize Time.now
+
+# good
+I18n.t :key
+I18n.l Time.now
+----
+
+==== EnforcedStyle: conservative (default)
+
+[source,ruby]
+----
+# good
+translate :key
+localize Time.now
+t :key
+l Time.now
+----
+
+==== EnforcedStyle: aggressive
+
+[source,ruby]
+----
+# bad
+translate :key
+localize Time.now
+
+# good
+t :key
+l Time.now
+----
+
+=== Configurable attributes
+
+|===
+| Name | Default value | Configurable values
+
+| EnforcedStyle
+| `conservative`
+| `conservative`, `aggressive`
+|===
+
+=== References
+
+* https://rails.rubystyle.guide/#short-i18n
+
 == Rails/SkipsModelValidations
 
 |===

lib/rubocop/cop/rails/short_i18n.rb

@@ -0,0 +1,76 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Rails
+      # This cop enforces that short forms of `I18n` methods are used:
+      # `t` instead of `translate` and `l` instead of `localize`.
+      #
+      # This cop has two different enforcement modes. When the EnforcedStyle
+      # is conservative (the default) then only `I18n.translate` and `I18n.localize`
+      # calls are added as offenses.
+      #
+      # When the EnforcedStyle is aggressive then all `translate` and `localize` calls
+      # without a receiver are added as offenses.
+      #
+      # @example
+      #   # bad
+      #   I18n.translate :key
+      #   I18n.localize Time.now
+      #
+      #   # good
+      #   I18n.t :key
+      #   I18n.l Time.now
+      #
+      # @example EnforcedStyle: conservative (default)
+      #   # good
+      #   translate :key
+      #   localize Time.now
+      #   t :key
+      #   l Time.now
+      #
+      # @example EnforcedStyle: aggressive
+      #   # bad
+      #   translate :key
+      #   localize Time.now
+      #
+      #   # good
+      #   t :key
+      #   l Time.now
+      #
+      class ShortI18n < Cop
+        include ConfigurableEnforcedStyle
+
+        MSG = 'Use `%<good_method>s` instead of `%<bad_method>s`.'
+
+        PREFERRED_METHODS = {
+          translate: :t,
+          localize: :l
+        }.freeze
+
+        def_node_matcher :long_i18n?, <<~PATTERN
+          (send {nil? (const nil? :I18n)} ${:translate :localize} ...)
+        PATTERN
+
+        def on_send(node)
+          return if style == :conservative && !node.receiver
+
+          long_i18n?(node) do |method_name|
+            good_method = PREFERRED_METHODS[method_name]
+            message = format(MSG, good_method: good_method, bad_method: method_name)
+
+            add_offense(node, location: :selector, message: message)
+          end
+        end
+
+        def autocorrect(node)
+          long_i18n?(node) do |method_name|
+            lambda do |corrector|
+              corrector.replace(node.loc.selector, PREFERRED_METHODS[method_name])
+            end
+          end
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/rails_cops.rb

@@ -69,6 +69,7 @@
 require_relative 'rails/safe_navigation_with_blank'
 require_relative 'rails/save_bang'
 require_relative 'rails/scope_args'
+require_relative 'rails/short_i18n'
 require_relative 'rails/skips_model_validations'
 require_relative 'rails/time_zone'
 require_relative 'rails/uniq_before_pluck'

spec/rubocop/cop/rails/short_i18n_spec.rb

@@ -0,0 +1,91 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::Rails::ShortI18n, :config do
+  subject(:cop) { described_class.new(config) }
+
+  shared_examples_for 'ShortI18n cop' do
+    it 'registers an offense and corrects when using `I18n.translate`' do
+      expect_offense(<<~RUBY)
+        I18n.translate :key
+             ^^^^^^^^^ Use `t` instead of `translate`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        I18n.t :key
+      RUBY
+    end
+
+    it 'registers an offense and corrects when using `I18n.localize`' do
+      expect_offense(<<~RUBY)
+        I18n.localize Time.now
+             ^^^^^^^^ Use `l` instead of `localize`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        I18n.l Time.now
+      RUBY
+    end
+
+    it 'does not register an offense when using `I18n.t`' do
+      expect_no_offenses('I18n.t :key')
+    end
+
+    it 'does not register an offense when using `I18n.l`' do
+      expect_no_offenses('I18n.l Time.now')
+    end
+
+    it 'does not register an offense when using `t`' do
+      expect_no_offenses('t :key')
+    end
+
+    it 'does not register an offense when using `l`' do
+      expect_no_offenses('l Time.now')
+    end
+  end
+
+  context 'when EnforcedStyle set to conservative' do
+    let(:cop_config) do
+      { 'EnforcedStyle' => 'conservative' }
+    end
+
+    it_behaves_like 'ShortI18n cop'
+
+    it 'does not register an offense when using `translate`' do
+      expect_no_offenses('translate :key')
+    end
+
+    it 'does not register an offense when using `localize`' do
+      expect_no_offenses('localize Time.now')
+    end
+  end
+
+  context 'when EnforcedStyle set to aggressive' do
+    let(:cop_config) do
+      { 'EnforcedStyle' => 'aggressive' }
+    end
+
+    it_behaves_like 'ShortI18n cop'
+
+    it 'registers an offense and corrects when using `translate`' do
+      expect_offense(<<~RUBY)
+        translate :key
+        ^^^^^^^^^ Use `t` instead of `translate`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        t :key
+      RUBY
+    end
+
+    it 'registers an offense and corrects when using `localize`' do
+      expect_offense(<<~RUBY)
+        localize Time.now
+        ^^^^^^^^ Use `l` instead of `localize`.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        l Time.now
+      RUBY
+    end
+  end
+end