Merge pull request #14 from ytjmt/disallow_ivar_in_class_methods_dsl

Disallow instance variables in `ActiveSupport::Concern#class_methods`

lib/rubocop/cop/thread_safety/instance_variable_in_class_method.rb

@@ -39,6 +39,14 @@ module ThreadSafety
       #   end
       #
       #   module Example
+      #     class_methods do
+      #       def test(params)
+      #         @params = params
+      #       end
+      #     end
+      #   end
+      #
+      #   module Example
       #     module_function
       #
       #     def test(params)
@@ -111,6 +119,19 @@ def in_def_sclass?(node)
         end
 
         def in_def_class_methods?(node)
+          in_def_class_methods_dsl?(node) || in_def_class_methods_module?(node)
+        end
+
+        def in_def_class_methods_dsl?(node)
+          node.ancestors.any? do |ancestor|
+            next unless ancestor.block_type?
+            next unless ancestor.children.first.is_a? AST::SendNode
+
+            ancestor.children.first.command? :class_methods
+          end
+        end
+
+        def in_def_class_methods_module?(node)
           defn = node.ancestors.find(&:def_type?)
           return unless defn
 

spec/rubocop/cop/thread_safety/instance_variable_in_class_method_spec.rb

@@ -71,6 +71,19 @@ def some_method(params)
     RUBY
   end
 
+  it 'registers an offense for assigning an ivar in class_methods' do
+    expect_offense(<<~RUBY)
+      module Test
+        class_methods do
+          def some_method(params)
+            @params = params
+            ^^^^^^^ Avoid instance variables in class methods.
+          end
+        end
+      end
+    RUBY
+  end
+
   it 'registers an offense for assigning an ivar in a class singleton method' do
     expect_offense(<<~RUBY)
       class Test
@@ -130,6 +143,19 @@ def some_method(params)
     RUBY
   end
 
+  it 'registers an offense for ivar_set in class_methods' do
+    expect_offense(<<~RUBY)
+      module Test
+        class_methods do
+          def some_method(params)
+            instance_variable_set(:@params, params)
+            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Avoid instance variables in class methods.
+          end
+        end
+      end
+    RUBY
+  end
+
   it 'registers an offense for ivar_set in define_singleton_method' do
     expect_offense(<<~RUBY)
       class Test