Add new Rails/RedundantReceiverInWithOptions cop

CHANGELOG.md

@@ -23,6 +23,7 @@
 * [#5077](https://github.com/bbatsov/rubocop/pull/5077): Add new `Rails/CreateTableWithTimestamps` cop. ([@wata727][])
 * Add new `Style/ColonMethodDefinition` cop. ([@rrosenblum][])
 * Add new `Style/ExtendSelf` cop. ([@drenmi][])
+* [#5185](https://github.com/bbatsov/rubocop/pull/5185): Add new `Rails/RedundantReceiverInWithOptions` cop. ([@koic][])
 
 ### Bug fixes
 

config/enabled.yml

@@ -1163,6 +1163,10 @@ Rails/ReadWriteAttribute:
   StyleGuide: 'https://github.com/bbatsov/rails-style-guide#read-attribute'
   Enabled: true
 
+Rails/RedundantReceiverInWithOptions:
+  Description: 'Checks for redundant receiver in `with_options`.'
+  Enabled: true
+
 Rails/RelativeDateConstant:
   Description: 'Do not assign relative date to constants.'
   Enabled: true

lib/rubocop.rb

@@ -525,6 +525,7 @@
 require_relative 'rubocop/cop/rails/pluralization_grammar'
 require_relative 'rubocop/cop/rails/present'
 require_relative 'rubocop/cop/rails/read_write_attribute'
+require_relative 'rubocop/cop/rails/redundant_receiver_in_with_options'
 require_relative 'rubocop/cop/rails/request_referer'
 require_relative 'rubocop/cop/rails/reversible_migration'
 require_relative 'rubocop/cop/rails/relative_date_constant'

lib/rubocop/cop/rails/redundant_receiver_in_with_options.rb

@@ -0,0 +1,91 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module Rails
+      # This cop checks for redundant receiver in `with_options`.
+      # Receiver is implicit from Rails 4.2 or higher.
+      #
+      # @example
+      #   # bad
+      #   class Account < ApplicationRecord
+      #     with_options dependent: :destroy do |assoc|
+      #       assoc.has_many :customers
+      #       assoc.has_many :products
+      #       assoc.has_many :invoices
+      #       assoc.has_many :expenses
+      #     end
+      #   end
+      #
+      #   # good
+      #   class Account < ApplicationRecord
+      #     with_options dependent: :destroy do
+      #       has_many :customers
+      #       has_many :products
+      #       has_many :invoices
+      #       has_many :expenses
+      #     end
+      #   end
+      class RedundantReceiverInWithOptions < Cop
+        extend TargetRailsVersion
+
+        minimum_target_rails_version 4.2
+
+        MSG = 'Redundant receiver in `with_options`.'.freeze
+
+        def_node_matcher :with_options?, <<-PATTERN
+          (block
+            (send nil? :with_options
+              (...))
+            (args
+              (...))
+            ...)
+        PATTERN
+
+        def_node_search :assoc_has_redundant_receiver, <<-PATTERN
+          (send
+            (lvar _) ...)
+        PATTERN
+
+        def on_block(node)
+          with_options?(node) do
+            assoc_has_redundant_receiver(node).each do |assoc|
+              add_offense(assoc, location: assoc.receiver.loc.expression)
+            end
+          end
+        end
+
+        def autocorrect(node)
+          lambda do |corrector|
+            corrector.remove(node.receiver.loc.expression)
+            corrector.remove(node.loc.dot)
+            corrector.remove(block_argument_range(node))
+          end
+        end
+
+        private
+
+        def block_argument_range(node)
+          block_argument = node.parent.parent.children[1].loc.expression
+
+          range_between(
+            search_begin_pos_of_space_before_block_argument(
+              block_argument.begin_pos
+            ),
+            block_argument.end_pos
+          )
+        end
+
+        def search_begin_pos_of_space_before_block_argument(begin_pos)
+          position = begin_pos - 1
+
+          if processed_source.raw_source[position] == ' '
+            search_begin_pos_of_space_before_block_argument(position)
+          else
+            begin_pos
+          end
+        end
+      end
+    end
+  end
+end

manual/cops.md

@@ -337,6 +337,7 @@ In the following section you find all available cops:
 * [Rails/PluralizationGrammar](cops_rails.md#railspluralizationgrammar)
 * [Rails/Present](cops_rails.md#railspresent)
 * [Rails/ReadWriteAttribute](cops_rails.md#railsreadwriteattribute)
+* [Rails/RedundantReceiverInWithOptions](cops_rails.md#railsredundantreceiverinwithoptions)
 * [Rails/RelativeDateConstant](cops_rails.md#railsrelativedateconstant)
 * [Rails/RequestReferer](cops_rails.md#railsrequestreferer)
 * [Rails/ReversibleMigration](cops_rails.md#railsreversiblemigration)

manual/cops_rails.md

@@ -907,6 +907,39 @@ Include | `app/models/**/*.rb` | Array
 
 * [https://github.com/bbatsov/rails-style-guide#read-attribute](https://github.com/bbatsov/rails-style-guide#read-attribute)
 
+## Rails/RedundantReceiverInWithOptions
+
+Enabled by default | Supports autocorrection
+--- | ---
+Enabled | Yes
+
+This cop checks for redundant receiver in `with_options`.
+Receiver is implicit from Rails 4.2 or higher.
+
+### Examples
+
+```ruby
+# bad
+class Account < ApplicationRecord
+  with_options dependent: :destroy do |assoc|
+    assoc.has_many :customers
+    assoc.has_many :products
+    assoc.has_many :invoices
+    assoc.has_many :expenses
+  end
+end
+
+# good
+class Account < ApplicationRecord
+  with_options dependent: :destroy do
+    has_many :customers
+    has_many :products
+    has_many :invoices
+    has_many :expenses
+  end
+end
+```
+
 ## Rails/RelativeDateConstant
 
 Enabled by default | Supports autocorrection

spec/rubocop/cop/rails/redundant_receiver_in_with_options_spec.rb

@@ -0,0 +1,81 @@
+# frozen_string_literal: true
+
+describe RuboCop::Cop::Rails::RedundantReceiverInWithOptions, :config do
+  subject(:cop) { described_class.new(config) }
+
+  context 'rails >= 4.2' do
+    let(:rails_version) { 4.2 }
+
+    it 'registers an offense when using explicit receiver in `with_options`' do
+      expect_offense(<<-RUBY.strip_indent)
+        class Account < ApplicationRecord
+          with_options dependent: :destroy do |assoc|
+            assoc.has_many :customers
+            ^^^^^ Redundant receiver in `with_options`.
+            assoc.has_many :products
+            ^^^^^ Redundant receiver in `with_options`.
+            assoc.has_many :invoices
+            ^^^^^ Redundant receiver in `with_options`.
+            assoc.has_many :expenses
+            ^^^^^ Redundant receiver in `with_options`.
+          end
+        end
+      RUBY
+    end
+
+    it 'does not register an offense when using inplicit receiver ' \
+       'in `with_options`' do
+      expect_no_offenses(<<-RUBY.strip_indent)
+        class Account < ApplicationRecord
+          with_options dependent: :destroy do
+            has_many :customers
+            has_many :products
+            has_many :invoices
+            has_many :expenses
+          end
+        end
+      RUBY
+    end
+
+    it 'autocorrects to implicit receiver in `with_options`' do
+      new_source = autocorrect_source(<<-RUBY.strip_indent)
+        class Account < ApplicationRecord
+          with_options dependent: :destroy do |assoc|
+            assoc.has_many :customers
+            assoc.has_many :products
+            assoc.has_many :invoices
+            assoc.has_many :expenses
+          end
+        end
+      RUBY
+
+      expect(new_source).to eq(<<-RUBY.strip_indent)
+        class Account < ApplicationRecord
+          with_options dependent: :destroy do
+            has_many :customers
+            has_many :products
+            has_many :invoices
+            has_many :expenses
+          end
+        end
+      RUBY
+    end
+  end
+
+  context 'rails <= 4.1' do
+    let(:rails_version) { 4.1 }
+
+    it 'registers an offense when using explicit receiver in `with_options`' do
+      expect_no_offenses(<<-RUBY.strip_indent)
+        class Account < ApplicationRecord
+          with_options dependent: :destroy do |assoc|
+            assoc.has_many :customers
+            assoc.has_many :products
+            assoc.has_many :invoices
+            assoc.has_many :expenses
+          end
+        end
+      RUBY
+    end
+  end
+end