Ensure that subclassed models have their own independent attributes

lib/mobility.rb

@@ -248,7 +248,7 @@ def translated_attribute_names
     end
 
     def inherited(subclass)
-      subclass.instance_variable_set(:@mobility, @mobility)
+      subclass.instance_variable_set(:@mobility, @mobility.dup)
       super
     end
   end

lib/mobility/wrapper.rb

@@ -27,5 +27,10 @@ def translated_attribute_names
     def << backend_module
       modules << backend_module
     end
+
+    def initialize_dup(other)
+      @modules = modules.map(&:dup)
+      super
+    end
   end
 end

spec/mobility_spec.rb

@@ -73,6 +73,16 @@ def attributes
           subclass = Class.new(model)
           expect(subclass.translated_attribute_names).to eq(["title"])
         end
+
+        it "defines new translated attributes independently of superclass" do
+          model.include Mobility
+          model.translates :title, backend: :null
+          subclass = Class.new(model)
+          subclass.translates :content, backend: :null
+
+          expect(model.translated_attribute_names).to eq(["title"])
+          expect(subclass.translated_attribute_names).to match_array(["title", "content"])
+        end
       end
     end