Merge pull request #43 from viralpraxis/make-class-attribute-detectio…

…n-configurable

Make `class_attribute` detection configurable

config/default.yml

@@ -5,6 +5,7 @@
 ThreadSafety/ClassAndModuleAttributes:
   Description: 'Avoid mutating class and module attributes.'
   Enabled: true
+  ActiveSupportClassAttributeAllowed: false
 
 ThreadSafety/InstanceVariableInClassMethod:
   Description: 'Avoid using instance variables in class methods.'

docs/modules/ROOT/pages/cops_threadsafety.adoc

@@ -32,6 +32,16 @@ class User
 end
 ----
 
+=== Configurable attributes
+
+|===
+| Name | Default value | Configurable values
+
+| ActiveSupportClassAttributeAllowed
+| `false`
+| Boolean
+|===
+
 == ThreadSafety/DirChdir
 
 |===

lib/rubocop/cop/thread_safety/class_and_module_attributes.rb

@@ -42,8 +42,15 @@ class ClassAndModuleAttributes < Base
             ...)
         MATCHER
 
+        # @!method class_attr?(node)
+        def_node_matcher :class_attr?, <<~MATCHER
+          (send nil?
+            :class_attribute
+            ...)
+        MATCHER
+
         def on_send(node)
-          return unless mattr?(node) || singleton_attr?(node)
+          return unless mattr?(node) || (!class_attribute_allowed? && class_attr?(node)) || singleton_attr?(node)
 
           add_offense(node)
         end
@@ -66,6 +73,10 @@ def defined_in_singleton_class?(node)
 
           false
         end
+
+        def class_attribute_allowed?
+          cop_config['ActiveSupportClassAttributeAllowed']
+        end
       end
     end
   end

spec/rubocop/cop/thread_safety/class_and_module_attributes_spec.rb

@@ -141,6 +141,27 @@ class Test
     RUBY
   end
 
+  it 'registers an offense for `class_attribute`' do
+    expect_offense(<<~RUBY)
+      class Test
+        class_attribute :foobar
+        ^^^^^^^^^^^^^^^^^^^^^^^ #{msg}
+      end
+    RUBY
+  end
+
+  context 'with `ActiveSupportClassAttributeAllowed` option set to `true`' do
+    let(:cop_config) { { 'ActiveSupportClassAttributeAllowed' => true } }
+
+    it 'does not register an offense for `class_attribute`' do
+      expect_no_offenses(<<~RUBY)
+        class Test
+          class_attribute :foobar
+        end
+      RUBY
+    end
+  end
+
   it 'registers no offense for other class macro calls' do
     expect_no_offenses(<<~RUBY)
       class Test