Fix duplicate extension cop versions when rubocop -V

Follow #9349 (comment). This PR fixes duplicate extension cop versions when `rubocop -V`. The following is an example: ```yaml # ext.yml require: - rubocop-rspec # .rubocop.yml inherit_from: ext.yml require: - rubocop-performance - rubocop-rspec ## Before If there are duplicate requires, extension cop display will also be duplicated. Duplicate requires will be displayed in duplicate. ```console % rubocop -V 1.8.0 (using Parser 3.0.0.0, rubocop-ast 1.4.0, running on ruby 2.7.2 x86_64-darwin19) - rubocop-performance 1.9.2 - rubocop-rspec 2.0.0 - rubocop-rspec 2.0.0 ``` ## After Even if there are duplicate requires, they will only be displayed once per extension cop. ```console % rubocop -V 1.8.0 (using Parser 3.0.0.0, rubocop-ast 1.4.0, running on ruby 2.7.2 x86_64-darwin19) - rubocop-performance 1.9.2 - rubocop-rspec 2.0.0 ```
rubocop · Jan 9, 2021 · 14858e4 · 14858e4
1 parent b096982
commit 14858e4
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diff --git a/changelog/fix_duplicate_ext_cop_versions_when_using_rubocop_verbose_version.md b/changelog/fix_duplicate_ext_cop_versions_when_using_rubocop_verbose_version.md
@@ -0,0 +1 @@
+* [#9356](https://github.com/rubocop-hq/rubocop/pull/9356): Fix duplicate extension cop versions when using `rubocop -V`. ([@koic][])
diff --git a/lib/rubocop/config_loader.rb b/lib/rubocop/config_loader.rb
@@ -175,7 +175,7 @@ def merge_with_default(config, config_file, unset_nil: true)
       end
 
       def loaded_features
-        @loaded_features.flatten.compact
+        @loaded_features.flatten.compact.uniq
       end
 
       # @api private

diff --git a/spec/rubocop/cli/cli_options_spec.rb b/spec/rubocop/cli/cli_options_spec.rb
@@ -177,6 +177,31 @@
       end
     end
 
+    context 'when requiring redundant extension cop' do
+      before do
+        create_file('ext.yml', <<~YAML)
+          require:
+            - rubocop-rspec
+        YAML
+        create_file('.rubocop.yml', <<~YAML)
+          inherit_from: ext.yml
+          require:
+            - rubocop-performance
+            - rubocop-rspec
+        YAML
+      end
+
+      it 'shows with version of each extension cop once' do
+        output = `ruby -I . "#{rubocop}" -V --disable-pending-cops`
+        expect(output).to include(RuboCop::Version::STRING)
+        expect(output).to match(/Parser \d+\.\d+\.\d+/)
+        expect(output).to match(/rubocop-ast \d+\.\d+\.\d+/)
+        expect(output).to match(
+          /- rubocop-performance \d+\.\d+\.\d+\n  - rubocop-rspec \d+\.\d+\.\d+\n\z/
+        )
+      end
+    end
+
     context 'when there are pending cops' do
       let(:pending_cop_warning) { <<~PENDING_COP_WARNING }
         The following cops were added to RuboCop, but are not configured. Please set Enabled to either `true` or `false` in your `.rubocop.yml` file.