Extract helper module to detect repeated nodes

lib/rubocop-rspec.rb

@@ -18,6 +18,7 @@
 require_relative 'rubocop/cop/rspec/mixin/location_help'
 require_relative 'rubocop/cop/rspec/mixin/metadata'
 require_relative 'rubocop/cop/rspec/mixin/namespace'
+require_relative 'rubocop/cop/rspec/mixin/repeated_items'
 require_relative 'rubocop/cop/rspec/mixin/skip_or_pending'
 require_relative 'rubocop/cop/rspec/mixin/top_level_group'
 require_relative 'rubocop/cop/rspec/mixin/variable'

lib/rubocop/cop/rspec/mixin/repeated_items.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module RSpec
+      # Helps find repeated items in a collection
+      #
+      # Provides a generic method to find repeated items by grouping them
+      # by a key and returning pairs of [item, repeated_lines] for items
+      # that appear more than once.
+      module RepeatedItems
+        # Groups items by key and returns only groups with more than one item
+        #
+        # @param items [Enumerable] the filtered collection to group
+        # @param key_proc [Proc] block returning the grouping key for each item
+        # @return [Array<Array>] array of groups containing more than one item
+        #   that share the same key and there are multiple items in the group
+        def find_repeated_groups(items, key_proc:)
+          items
+            .group_by(&key_proc)
+            .values
+            .reject(&:one?)
+        end
+
+        # Maps a group of items to pairs of [item, repeated_lines]
+        #
+        # @param items [Array] array of items that share the same key
+        # @return [Array<Array>] array of [item, repeated_lines] pairs
+        def add_repeated_lines(items)
+          repeated_lines = items.map(&:first_line)
+          items.map { |item| [item, repeated_lines - [item.first_line]] }
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/rspec/repeated_example.rb

@@ -16,6 +16,8 @@ module RSpec
       #   end
       #
       class RepeatedExample < Base
+        include RepeatedItems
+
         MSG = "Don't repeat examples within an example group. " \
               'Repeated on line(s) %<lines>s.'
 
@@ -32,10 +34,10 @@ def on_block(node) # rubocop:disable InternalAffairs/NumblockHandler
         def find_repeated_examples(node)
           examples = RuboCop::RSpec::ExampleGroup.new(node).examples
 
-          examples
-            .group_by { |example| build_example_signature(example) }
-            .values
-            .select { |group| group.size > 1 }
+          find_repeated_groups(
+            examples,
+            key_proc: ->(example) { build_example_signature(example) }
+          )
         end
 
         def build_example_signature(example)

lib/rubocop/cop/rspec/repeated_example_group_body.rb

@@ -44,6 +44,7 @@ module RSpec
       #
       class RepeatedExampleGroupBody < Base
         include SkipOrPending
+        include RepeatedItems
 
         MSG = 'Repeated %<group>s block body on line(s) %<loc>s'
 
@@ -72,19 +73,14 @@ def on_begin(node)
         private
 
         def repeated_group_bodies(node)
-          node
-            .children
+          items = node.children
             .select { |child| example_group_with_body?(child) }
             .reject { |child| skip_or_pending_inside_block?(child) }
-            .group_by { |group| signature_keys(group) }
-            .values
-            .reject(&:one?)
-            .flat_map { |groups| add_repeated_lines(groups) }
-        end
 
-        def add_repeated_lines(groups)
-          repeated_lines = groups.map(&:first_line)
-          groups.map { |group| [group, repeated_lines - [group.first_line]] }
+          find_repeated_groups(
+            items,
+            key_proc: ->(group) { signature_keys(group) }
+          ).flat_map { |group| add_repeated_lines(group) }
         end
 
         def signature_keys(group)

lib/rubocop/cop/rspec/repeated_example_group_description.rb

@@ -44,6 +44,7 @@ module RSpec
       #
       class RepeatedExampleGroupDescription < Base
         include SkipOrPending
+        include RepeatedItems
 
         MSG = 'Repeated %<group>s block description on line(s) %<loc>s'
 
@@ -71,20 +72,15 @@ def on_begin(node)
         private
 
         def repeated_group_descriptions(node)
-          node
-            .children
+          items = node.children
             .select { |child| example_group?(child) }
             .reject { |child| skip_or_pending_inside_block?(child) }
             .reject { |child| empty_description?(child) }
-            .group_by { |group| doc_string_and_metadata(group) }
-            .values
-            .reject(&:one?)
-            .flat_map { |groups| add_repeated_lines(groups) }
-        end
 
-        def add_repeated_lines(groups)
-          repeated_lines = groups.map(&:first_line)
-          groups.map { |group| [group, repeated_lines - [group.first_line]] }
+          find_repeated_groups(
+            items,
+            key_proc: ->(group) { doc_string_and_metadata(group) }
+          ).flat_map { |group| add_repeated_lines(group) }
         end
 
         def message(group, repeats)

lib/rubocop/cop/rspec/repeated_include_example.rb

@@ -46,6 +46,8 @@ module RSpec
       #   end
       #
       class RepeatedIncludeExample < Base
+        include RepeatedItems
+
         MSG = 'Repeated include of shared_examples %<name>s ' \
               'on line(s) %<repeat>s'
 
@@ -73,25 +75,20 @@ def on_begin(node)
         private
 
         def repeated_include_examples(node)
-          node
-            .children
+          items = node.children
             .select { |child| literal_include_examples?(child) }
-            .group_by { |child| signature_keys(child) }
-            .values
-            .reject(&:one?)
-            .flat_map { |items| add_repeated_lines(items) }
+
+          find_repeated_groups(
+            items,
+            key_proc: ->(child) { signature_keys(child) }
+          ).flat_map { |group| add_repeated_lines(group) }
         end
 
         def literal_include_examples?(node)
           include_examples?(node) &&
             node.arguments.all?(&:recursive_literal_or_const?)
         end
 
-        def add_repeated_lines(items)
-          repeated_lines = items.map(&:first_line)
-          items.map { |item| [item, repeated_lines - [item.first_line]] }
-        end
-
         def signature_keys(item)
           item.arguments
         end

lib/rubocop/cop/rspec/scattered_setup.rb

@@ -42,6 +42,7 @@ module RSpec
       class ScatteredSetup < Base
         include FinalEndLocation
         include RangeHelp
+        include RepeatedItems
         extend AutoCorrector
 
         MSG = 'Do not define multiple `%<hook_name>s` hooks in the same ' \
@@ -63,17 +64,14 @@ def on_block(node) # rubocop:disable InternalAffairs/NumblockHandler
         private
 
         def repeated_hooks(node) # rubocop:disable Metrics/CyclomaticComplexity
-          hooks = RuboCop::RSpec::ExampleGroup.new(node)
-            .hooks
+          hooks = RuboCop::RSpec::ExampleGroup.new(node).hooks
             .reject(&:inside_class_method?)
             .select { |hook| hook.knowable_scope? && hook.name != :around }
-            .group_by { |hook| [hook.name, hook.scope, hook.metadata] }
-            .values
-            .reject(&:one?)
 
-          hooks.map do |hook|
-            hook.map(&:to_node)
-          end
+          find_repeated_groups(
+            hooks,
+            key_proc: ->(hook) { [hook.name, hook.scope, hook.metadata] }
+          ).map { |hook_group| hook_group.map(&:to_node) }
         end
 
         def lines_msg(numbers)