Fix DuplicateKeyError when the whole class is reloaded

Author: flvrone

lib/ruby-enum/enum.rb

@@ -19,6 +19,9 @@ def self.included(base)
       base.extend ClassMethods
 
       base.private_class_method(:new)
+
+      base.instance_variable_set(:@_enum_hash, {})
+      base.instance_variable_set(:@_enums_by_value, {})
     end
 
     module ClassMethods

spec/ruby-enum/enum_spec.rb

@@ -229,6 +229,22 @@ class SecondSubclass < FirstSubclass
     end
   end
 
+  # rubocop:disable Rspec/DescribedClass
+  describe 'Reloading enum definition' do
+    it 'plays nice with lazy loading in Ruby on Rails' do
+      class_body = proc do
+        include Ruby::Enum
+
+        define :BALD, 'bald'
+      end
+
+      HairStyles = Class.new(&class_body)
+
+      expect { HairStyles.class_eval(&class_body) }.not_to raise_error
+    end
+  end
+  # rubocop:enable Rspec/DescribedClass
+
   describe 'Given a class that has not defined any enums' do
     class EmptyEnums
       include Ruby::Enum