Add RSpec/MemoizedHelperBlockDelimiter cop

.rubocop.yml

@@ -118,6 +118,8 @@ RSpec/ExcessiveDocstringSpacing:
   Enabled: true
 RSpec/IdenticalEqualityAssertion:
   Enabled: true
+RSpec/MemoizedHelperBlockDelimiter:
+  Enabled: true
 RSpec/NoExpectationExample:
   Enabled: true
 RSpec/SortMetadata:

CHANGELOG.md

@@ -14,6 +14,7 @@
 * Update `config/default.yml` removing deprecated option to make the config correctable by users. ([@ignaciovillaverde][])
 * Do not attempt to auto-correct example groups with `include_examples` in `RSpec/LetBeforeExamples`. ([@pirj][])
 * Add new `RSpec/SortMetadata` cop. ([@leoarnold][])
+* Add `RSpec/MemoizedHelperBlockDelimiter` cop. ([@r7kamura][])
 
 ## 2.13.2 (2022-09-23)
 

config/default.yml

@@ -558,6 +558,16 @@ RSpec/LetSetup:
   VersionAdded: '1.7'
   Reference: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/LetSetup
 
+RSpec/MemoizedHelperBlockDelimiter:
+  Description: Use consistent style block delimiters for memoized helpers.
+  Enabled: pending
+  EnforcedStyle: do_end
+  SupportedStyles:
+    - braces
+    - do_end
+  VersionAdded: "<<next>>"
+  Reference: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/MemoizedHelperBlockDelimiter
+
 RSpec/MessageChain:
   Description: Check that chains of messages are not being stubbed.
   Enabled: true

docs/modules/ROOT/pages/cops.adoc

@@ -52,6 +52,7 @@
 * xref:cops_rspec.adoc#rspecleakyconstantdeclaration[RSpec/LeakyConstantDeclaration]
 * xref:cops_rspec.adoc#rspecletbeforeexamples[RSpec/LetBeforeExamples]
 * xref:cops_rspec.adoc#rspecletsetup[RSpec/LetSetup]
+* xref:cops_rspec.adoc#rspecmemoizedhelperblockdelimiter[RSpec/MemoizedHelperBlockDelimiter]
 * xref:cops_rspec.adoc#rspecmessagechain[RSpec/MessageChain]
 * xref:cops_rspec.adoc#rspecmessageexpectation[RSpec/MessageExpectation]
 * xref:cops_rspec.adoc#rspecmessagespies[RSpec/MessageSpies]

docs/modules/ROOT/pages/cops_rspec.adoc

@@ -2800,6 +2800,78 @@ end
 
 * https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/LetSetup
 
+== RSpec/MemoizedHelperBlockDelimiter
+
+|===
+| Enabled by default | Safe | Supports autocorrection | Version Added | Version Changed
+
+| Pending
+| Yes
+| Yes
+| <<next>>
+| -
+|===
+
+Use consistent style block delimiters for memoized helpers.
+
+=== Examples
+
+==== EnforcedStyle: do_end (default)
+
+[source,ruby]
+----
+# bad
+let(:foo) { 'bar' }
+
+# good
+let(:foo) do
+  'bar'
+end
+
+# bad
+subject(:foo) { 'bar' }
+
+# good
+subject(:foo) do
+  'bar'
+end
+----
+
+==== EnforcedStyle: braces
+
+[source,ruby]
+----
+# bad
+let(:foo) do
+  'bar'
+end
+
+# good
+let(:foo) { 'bar' }
+
+# bad
+subject(:foo) do
+  'bar'
+end
+
+# good
+subject(:foo) { 'bar' }
+----
+
+=== Configurable attributes
+
+|===
+| Name | Default value | Configurable values
+
+| EnforcedStyle
+| `do_end`
+| `braces`, `do_end`
+|===
+
+=== References
+
+* https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/MemoizedHelperBlockDelimiter
+
 == RSpec/MessageChain
 
 |===

lib/rubocop/cop/rspec/memoized_helper_block_delimiter.rb

@@ -0,0 +1,135 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module RSpec
+      # Use consistent style block delimiters for memoized helpers.
+      #
+      # @example EnforcedStyle: do_end (default)
+      #   # bad
+      #   let(:foo) { 'bar' }
+      #
+      #   # good
+      #   let(:foo) do
+      #     'bar'
+      #   end
+      #
+      #   # bad
+      #   subject(:foo) { 'bar' }
+      #
+      #   # good
+      #   subject(:foo) do
+      #     'bar'
+      #   end
+      #
+      # @example EnforcedStyle: braces
+      #   # bad
+      #   let(:foo) do
+      #     'bar'
+      #   end
+      #
+      #   # good
+      #   let(:foo) { 'bar' }
+      #
+      #   # bad
+      #   subject(:foo) do
+      #     'bar'
+      #   end
+      #
+      #   # good
+      #   subject(:foo) { 'bar' }
+      class MemoizedHelperBlockDelimiter < Base
+        extend AutoCorrector
+
+        include ConfigurableEnforcedStyle
+        include RangeHelp
+        include RuboCop::RSpec::Language
+
+        # @param node [RuboCop::AST::BlockNode]
+        # @return [void]
+        def on_block(node) # rubocop:disable InternalAffairs/NumblockHandler
+          return unless bad?(node)
+
+          add_offense(
+            node.location.begin.with(
+              end_pos: node.location.end.end_pos
+            ),
+            message: "Use #{style} style block delimiters."
+          ) do |corrector|
+            autocorrect(corrector, node)
+          end
+        end
+
+        private
+
+        # @param corrector [RuboCop::Cop::Corrector]
+        # @param node [RuboCop::AST::BlockNode]
+        # @return [void]
+        def autocorrect(corrector, node)
+          case style
+          when :braces
+            # Not supported because it conflicts with Style/BlockDelimiters.
+          when :do_end
+            autocorrect_braces(corrector, node)
+          end
+        end
+
+        # @param corrector [RuboCop::Cop::Corrector]
+        # @param node [RuboCop::AST::BlockNode]
+        # @return [void]
+        def autocorrect_braces(corrector, node)
+          unless whitespace_before?(node.location.begin)
+            corrector.insert_before(node.location.begin, ' ')
+          end
+          corrector.replace(node.location.begin, 'do')
+          corrector.replace(node.location.end, 'end')
+          wrap_in_newlines(corrector, node) if node.single_line?
+        end
+
+        # @param node [RuboCop::AST::BlockNode]
+        # @return [Boolean]
+        def bad?(node)
+          memoized_helper_method?(node) &&
+            !preferred_block_delimiter?(node)
+        end
+
+        # @param node [RuboCop::AST::BlockNode]
+        # @return [Boolean]
+        def memoized_helper_method?(node)
+          let?(node) || subject?(node)
+        end
+
+        # @param node [RuboCop::AST::BlockNode]
+        # @return [Boolean]
+        def preferred_block_delimiter?(node)
+          case style
+          when :braces
+            node.braces?
+          when :do_end
+            !node.braces?
+          end
+        end
+
+        # @param range [Parser::Source::Range]
+        # @return [Boolean]
+        def whitespace_before?(range)
+          range.source_buffer.source[range.begin_pos - 1].match?(/\s/)
+        end
+
+        # @param corrector [RuboCop::Cop::Corrector]
+        # @param node [RuboCop::AST::BlockNode]
+        # @return [void]
+        def wrap_in_newlines(corrector, node)
+          corrector.wrap(
+            node.location.begin.with(
+              begin_pos: node.location.begin.end_pos,
+              end_pos: node.location.end.begin_pos
+            ),
+            "\n",
+            "\n"
+          )
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/rspec_cops.rb

@@ -73,6 +73,7 @@
 require_relative 'rspec/leaky_constant_declaration'
 require_relative 'rspec/let_before_examples'
 require_relative 'rspec/let_setup'
+require_relative 'rspec/memoized_helper_block_delimiter'
 require_relative 'rspec/message_chain'
 require_relative 'rspec/message_expectation'
 require_relative 'rspec/message_spies'

spec/project/changelog_spec.rb

@@ -1,7 +1,9 @@
 # frozen_string_literal: true
 
 RSpec.describe 'CHANGELOG.md' do
-  subject(:changelog) { SpecHelper::ROOT.join('CHANGELOG.md').read }
+  subject(:changelog) do
+    SpecHelper::ROOT.join('CHANGELOG.md').read
+  end
 
   it 'has link definitions for all implicit links' do
     implicit_link_names = changelog.scan(/\[([^\]]+)\]\[\]/).flatten.uniq
@@ -32,9 +34,13 @@
   end
 
   describe 'entry' do
-    subject(:entries) { lines.grep(/^\*/).map(&:chomp) }
+    subject(:entries) do
+      lines.grep(/^\*/).map(&:chomp)
+    end
 
-    let(:lines) { changelog.each_line }
+    let(:lines) do
+      changelog.each_line
+    end
 
     it 'has a whitespace between the * and the body' do
       expect(entries).to all(match(/^\* \S/))

spec/rubocop/cli/autocorrect_spec.rb

@@ -1,7 +1,9 @@
 # frozen_string_literal: true
 
 RSpec.describe 'RuboCop::CLI --autocorrect' do # rubocop:disable RSpec/DescribeClass
-  subject(:cli) { RuboCop::CLI.new }
+  subject(:cli) do
+    RuboCop::CLI.new
+  end
 
   include_context 'isolated environment'
 

spec/rubocop/cop/rspec/base_spec.rb

@@ -1,8 +1,12 @@
 # frozen_string_literal: true
 
 RSpec.describe RuboCop::Cop::RSpec::Base do
-  let(:cop_class) { RuboCop::RSpec::FakeCop }
-  let(:cop_config) { { 'Exclude' => %w[bar_spec.rb] } }
+  let(:cop_class) do
+    RuboCop::RSpec::FakeCop
+  end
+  let(:cop_config) do
+    { 'Exclude' => %w[bar_spec.rb] }
+  end
 
   before do
     stub_const('RuboCop::RSpec::FakeCop',
@@ -89,7 +93,9 @@ def on_block(node) # rubocop:disable InternalAffairs/NumblockHandler
                  end)
     end
 
-    let(:cop_class) { RuboCop::RSpec::ExampleGroupHaterCop }
+    let(:cop_class) do
+      RuboCop::RSpec::ExampleGroupHaterCop
+    end
 
     shared_examples_for 'it detects `describe`' do
       it 'detects `describe` as an example group' do

spec/rubocop/cop/rspec/be_nil_spec.rb

@@ -6,7 +6,9 @@
   end
 
   context 'with EnforcedStyle `be_nil`' do
-    let(:enforced_style) { 'be_nil' }
+    let(:enforced_style) do
+      'be_nil'
+    end
 
     it 'registers an offense when using `#be` for `nil` value' do
       expect_offense(<<~RUBY)
@@ -37,7 +39,9 @@
   end
 
   context 'with EnforcedStyle `be`' do
-    let(:enforced_style) { 'be' }
+    let(:enforced_style) do
+      'be'
+    end
 
     it 'does not register an offense when using `#be` for `nil` value' do
       expect_no_offenses(<<~RUBY)

spec/rubocop/cop/rspec/capybara/feature_methods_spec.rb

@@ -133,7 +133,9 @@
   end
 
   context 'with configured `EnabledMethods`' do
-    let(:cop_config) { { 'EnabledMethods' => %w[feature] } }
+    let(:cop_config) do
+      { 'EnabledMethods' => %w[feature] }
+    end
 
     it 'ignores usage of the enabled method' do
       expect_no_offenses(<<-RUBY)

spec/rubocop/cop/rspec/capybara/negation_matcher_spec.rb

@@ -1,10 +1,14 @@
 # frozen_string_literal: true
 
 RSpec.describe RuboCop::Cop::RSpec::Capybara::NegationMatcher, :config do
-  let(:cop_config) { { 'EnforcedStyle' => enforced_style } }
+  let(:cop_config) do
+    { 'EnforcedStyle' => enforced_style }
+  end
 
   context 'with EnforcedStyle `have_no`' do
-    let(:enforced_style) { 'have_no' }
+    let(:enforced_style) do
+      'have_no'
+    end
 
     %i[selector css xpath text title current_path link button
        field checked_field unchecked_field select table
@@ -50,7 +54,9 @@
   end
 
   context 'with EnforcedStyle `not_to`' do
-    let(:enforced_style) { 'not_to' }
+    let(:enforced_style) do
+      'not_to'
+    end
 
     %i[selector css xpath text title current_path link button
        field checked_field unchecked_field select table