Prevent redundant plugin loading

koic · bbatsov · commit a11862402ce9 · 2025-03-13T07:46:10.000+02:00
This PR prevents redundant plugin loading
when a duplicate plugin is specified in an inherited config.
diff --git a/changelog/fix_prevent_redundant_plugin_loading.md b/changelog/fix_prevent_redundant_plugin_loading.md
@@ -0,0 +1 @@
+* [#13981](https://github.com/rubocop/rubocop/pull/13981): Prevent redundant plugin loading when a duplicate plugin is specified in an inherited config. ([@koic][])
diff --git a/lib/rubocop/config_loader_resolver.rb b/lib/rubocop/config_loader_resolver.rb
@@ -9,7 +9,8 @@ module RuboCop
   # @api private
   class ConfigLoaderResolver # rubocop:disable Metrics/ClassLength
     def resolve_plugins(rubocop_config, plugins)
-      return if (plugins = Array(plugins)).empty?
+      plugins = Array(plugins) - ConfigLoader.loaded_plugins.map { |plugin| plugin.about.name }
+      return if plugins.empty?
 
       Plugin.integrate_plugins(rubocop_config, plugins)
     end
diff --git a/spec/rubocop/version_spec.rb b/spec/rubocop/version_spec.rb
@@ -104,6 +104,48 @@ module FooBarBaz
       end
     end
 
+    context 'when plugins are specified' do
+      before do
+        create_file('.rubocop.yml', <<~YAML)
+          plugins:
+            - rubocop-performance
+            - rubocop-rspec
+        YAML
+      end
+
+      it 'returns the extensions' do
+        expect(extension_versions).to contain_exactly(
+          /- rubocop-performance \d+\.\d+\.\d+/,
+          /- rubocop-rspec \d+\.\d+\.\d+/
+        )
+      end
+    end
+
+    context 'when a duplicate plugin is specified in an inherited config' do
+      before do
+        create_file('base.yml', <<~YAML)
+          plugins:
+            - rubocop-performance
+        YAML
+
+        create_file('.rubocop.yml', <<~YAML)
+          inherit_from:
+            - base.yml
+
+          plugins:
+            - rubocop-performance
+            - rubocop-rspec
+        YAML
+      end
+
+      it 'returns each extension exactly once' do
+        expect(extension_versions).to contain_exactly(
+          /- rubocop-performance \d+\.\d+\.\d+/,
+          /- rubocop-rspec \d+\.\d+\.\d+/
+        )
+      end
+    end
+
     context 'with an invalid cop in config' do
       before do
         create_file('.rubocop.yml', <<~YAML)

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1 @@`
	`1`	`+* [#13981](https://github.com/rubocop/rubocop/pull/13981): Prevent redundant plugin loading when a duplicate plugin is specified in an inherited config. ([@koic][])`