Add RSpec/DuplicatedMetadata cop

.rubocop.yml

@@ -116,6 +116,8 @@ RSpec/ChangeByZero:
   Enabled: true
 RSpec/ClassCheck:
   Enabled: true
+RSpec/DuplicatedMetadata:
+  Enabled: true
 RSpec/ExcessiveDocstringSpacing:
   Enabled: true
 RSpec/IdenticalEqualityAssertion:

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - Add new `RSpec/FactoryBot/FactoryNameStyle` cop. ([@ydah])
 - Fix wrong autocorrection in `n_times` style on `RSpec/FactoryBot/CreateList`. ([@r7kamura])
+- Add `RSpec/DuplicatedMetadata` cop. ([@r7kamura])
 
 ## 2.15.0 (2022-11-03)
 

config/default.yml

@@ -284,6 +284,12 @@ RSpec/Dialect:
   VersionAdded: '1.33'
   Reference: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/Dialect
 
+RSpec/DuplicatedMetadata:
+  Description: Avoid duplicated metadata.
+  Enabled: pending
+  VersionAdded: "<<next>>"
+  Reference: https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/DuplicatedMetadata
+
 RSpec/EmptyExampleGroup:
   Description: Checks if an example group does not include any tests.
   Enabled: true

docs/modules/ROOT/pages/cops.adoc

@@ -21,6 +21,7 @@
 * xref:cops_rspec.adoc#rspecdescribedclass[RSpec/DescribedClass]
 * xref:cops_rspec.adoc#rspecdescribedclassmodulewrapping[RSpec/DescribedClassModuleWrapping]
 * xref:cops_rspec.adoc#rspecdialect[RSpec/Dialect]
+* xref:cops_rspec.adoc#rspecduplicatedmetadata[RSpec/DuplicatedMetadata]
 * xref:cops_rspec.adoc#rspecemptyexamplegroup[RSpec/EmptyExampleGroup]
 * xref:cops_rspec.adoc#rspecemptyhook[RSpec/EmptyHook]
 * xref:cops_rspec.adoc#rspecemptylineafterexample[RSpec/EmptyLineAfterExample]

docs/modules/ROOT/pages/cops_rspec.adoc

@@ -1001,6 +1001,35 @@ end
 
 * https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/Dialect
 
+== RSpec/DuplicatedMetadata
+
+|===
+| Enabled by default | Safe | Supports autocorrection | Version Added | Version Changed
+
+| Pending
+| Yes
+| Yes
+| <<next>>
+| -
+|===
+
+Avoid duplicated metadata.
+
+=== Examples
+
+[source,ruby]
+----
+# bad
+describe 'Something', :a, :a
+
+# good
+describe 'Something', :a
+----
+
+=== References
+
+* https://www.rubydoc.info/gems/rubocop-rspec/RuboCop/Cop/RSpec/DuplicatedMetadata
+
 == RSpec/EmptyExampleGroup
 
 |===

lib/rubocop-rspec.rb

@@ -25,6 +25,7 @@
 require_relative 'rubocop/cop/rspec/mixin/css_selector'
 require_relative 'rubocop/cop/rspec/mixin/skip_or_pending'
 require_relative 'rubocop/cop/rspec/mixin/capybara_help'
+require_relative 'rubocop/cop/rspec/mixin/metadata'
 
 require_relative 'rubocop/rspec/concept'
 require_relative 'rubocop/rspec/example_group'

lib/rubocop/cop/rspec/duplicated_metadata.rb

@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module RSpec
+      # Avoid duplicated metadata.
+      #
+      # @example
+      #   # bad
+      #   describe 'Something', :a, :a
+      #
+      #   # good
+      #   describe 'Something', :a
+      class DuplicatedMetadata < Base
+        extend AutoCorrector
+
+        include Metadata
+        include RangeHelp
+
+        MSG = 'Avoid duplicated metadata.'
+
+        def on_metadata(symbols, _pairs)
+          symbols.each do |symbol|
+            on_metadata_symbol(symbol)
+          end
+        end
+
+        private
+
+        def on_metadata_symbol(node)
+          return unless duplicated?(node)
+
+          add_offense(node) do |corrector|
+            autocorrect(corrector, node)
+          end
+        end
+
+        def autocorrect(corrector, node)
+          corrector.remove(
+            range_with_surrounding_comma(
+              range_with_surrounding_space(
+                node.location.expression,
+                side: :left
+              ),
+              :left
+            )
+          )
+        end
+
+        def duplicated?(node)
+          node.left_siblings.any? do |sibling|
+            sibling.eql?(node)
+          end
+        end
+      end
+    end
+  end
+end

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

@@ -0,0 +1,49 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module RSpec
+      # Helper methods to find RSpec metadata.
+      module Metadata
+        extend RuboCop::NodePattern::Macros
+
+        include RuboCop::RSpec::Language
+
+        # @!method rspec_metadata(node)
+        def_node_matcher :rspec_metadata, <<~PATTERN
+          (block
+            (send
+              #rspec? {#Examples.all #ExampleGroups.all #SharedGroups.all #Hooks.all} _ ${send str sym}* (hash $...)?)
+            ...)
+        PATTERN
+
+        # @!method rspec_configure(node)
+        def_node_matcher :rspec_configure, <<~PATTERN
+          (block (send #rspec? :configure) (args (arg $_)) ...)
+        PATTERN
+
+        # @!method metadata_in_block(node)
+        def_node_search :metadata_in_block, <<~PATTERN
+          (send (lvar %) #Hooks.all _ ${send str sym}* (hash $...)?)
+        PATTERN
+
+        def on_block(node)
+          rspec_configure(node) do |block_var|
+            metadata_in_block(node, block_var) do |symbols, pairs|
+              on_metadata(symbols, pairs.flatten)
+            end
+          end
+
+          rspec_metadata(node) do |symbols, pairs|
+            on_metadata(symbols, pairs.flatten)
+          end
+        end
+        alias on_numblock on_block
+
+        def on_metadata(_symbols, _pairs)
+          raise ::NotImplementedError
+        end
+      end
+    end
+  end
+end

lib/rubocop/cop/rspec/sort_metadata.rb

@@ -18,45 +18,12 @@ module RSpec
       #
       class SortMetadata < Base
         extend AutoCorrector
+        include Metadata
         include RangeHelp
 
         MSG = 'Sort metadata alphabetically.'
 
-        # @!method rspec_metadata(node)
-        def_node_matcher :rspec_metadata, <<~PATTERN
-          (block
-            (send
-              #rspec? {#Examples.all #ExampleGroups.all #SharedGroups.all #Hooks.all} _ ${send str sym}* (hash $...)?)
-            ...)
-        PATTERN
-
-        # @!method rspec_configure(node)
-        def_node_matcher :rspec_configure, <<~PATTERN
-          (block (send #rspec? :configure) (args (arg $_)) ...)
-        PATTERN
-
-        # @!method metadata_in_block(node)
-        def_node_search :metadata_in_block, <<~PATTERN
-          (send (lvar %) #Hooks.all _ ${send str sym}* (hash $...)?)
-        PATTERN
-
-        def on_block(node)
-          rspec_configure(node) do |block_var|
-            metadata_in_block(node, block_var) do |symbols, pairs|
-              investigate(symbols, pairs.flatten)
-            end
-          end
-
-          rspec_metadata(node) do |symbols, pairs|
-            investigate(symbols, pairs.flatten)
-          end
-        end
-
-        alias on_numblock on_block
-
-        private
-
-        def investigate(symbols, pairs)
+        def on_metadata(symbols, pairs)
           return if sorted?(symbols, pairs)
 
           crime_scene = crime_scene(symbols, pairs)
@@ -65,6 +32,8 @@ def investigate(symbols, pairs)
           end
         end
 
+        private
+
         def crime_scene(symbols, pairs)
           metadata = symbols + pairs
 

lib/rubocop/cop/rspec_cops.rb

@@ -43,6 +43,7 @@
 require_relative 'rspec/described_class'
 require_relative 'rspec/described_class_module_wrapping'
 require_relative 'rspec/dialect'
+require_relative 'rspec/duplicated_metadata'
 require_relative 'rspec/empty_example_group'
 require_relative 'rspec/empty_hook'
 require_relative 'rspec/empty_line_after_example'

spec/rubocop/cop/rspec/duplicated_metadata_spec.rb

@@ -0,0 +1,100 @@
+# frozen_string_literal: true
+
+RSpec.describe RuboCop::Cop::RSpec::DuplicatedMetadata do
+  context 'when metadata is not used' do
+    it 'registers no offense' do
+      expect_no_offenses(<<~RUBY)
+        describe 'Something' do
+        end
+      RUBY
+    end
+  end
+
+  context 'when metadata is not duplicated' do
+    it 'registers no offense' do
+      expect_no_offenses(<<~RUBY)
+        describe 'Something', :a, :b do
+        end
+      RUBY
+    end
+  end
+
+  context 'when metadata is duplicated on example group' do
+    it 'registers offense' do
+      expect_offense(<<~RUBY)
+        describe 'Something', :a, :a do
+                                  ^^ Avoid duplicated metadata.
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        describe 'Something', :a do
+        end
+      RUBY
+    end
+  end
+
+  context 'when metadata is duplicated in different order' do
+    it 'registers offense' do
+      expect_offense(<<~RUBY)
+        describe 'Something', :a, :b, :a do
+                                      ^^ Avoid duplicated metadata.
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        describe 'Something', :a, :b do
+        end
+      RUBY
+    end
+  end
+
+  context 'when metadata is duplicated on example' do
+    it 'registers offense' do
+      expect_offense(<<~RUBY)
+        it 'does something', :a, :a do
+                                 ^^ Avoid duplicated metadata.
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        it 'does something', :a do
+        end
+      RUBY
+    end
+  end
+
+  context 'when metadata is duplicated on shared examples' do
+    it 'registers offense' do
+      expect_offense(<<~RUBY)
+        shared_examples 'something', :a, :a do
+                                         ^^ Avoid duplicated metadata.
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        shared_examples 'something', :a do
+        end
+      RUBY
+    end
+  end
+
+  context 'when metadata is duplicated on configuration hook' do
+    it 'registers offense' do
+      expect_offense(<<~RUBY)
+        RSpec.configure do |configuration|
+          configuration.before(:each, :a, :a) do
+                                          ^^ Avoid duplicated metadata.
+          end
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        RSpec.configure do |configuration|
+          configuration.before(:each, :a) do
+          end
+        end
+      RUBY
+    end
+  end
+end