Field prefix is now configurable

lib/mongoid/enum.rb

@@ -1,5 +1,6 @@
 require "mongoid/enum/version"
 require "mongoid/enum/validators/multiple_validator"
+require "mongoid/enum/configuration"
 
 module Mongoid
   module Enum
@@ -7,7 +8,7 @@ module Mongoid
     module ClassMethods
 
       def enum(name, values, options = {})
-        field_name = :"_#{name}"
+        field_name = :"#{Mongoid::Enum.configuration.field_name_prefix}#{name}"
         options = default_options(values).merge(options)
 
         set_values_constant name, values

lib/mongoid/enum/configuration.rb

@@ -0,0 +1,19 @@
+module Mongoid
+  module Enum
+    class Configuration
+      attr_accessor :field_name_prefix
+
+      def initialize
+        self.field_name_prefix = '_'
+      end
+    end
+
+    def self.configuration
+      @configuration ||= Configuration.new
+    end
+
+    def self.configure
+      yield(configuration) if block_given?
+    end
+  end
+end

spec/mongoid/configuration_spec.rb

@@ -0,0 +1,11 @@
+require 'spec_helper'
+
+describe Mongoid::Enum::Configuration do
+  subject { Mongoid::Enum::Configuration.new }
+
+  describe "field_name_prefix" do
+    it "has '_' as default value" do
+      expect(subject.field_name_prefix).to eq '_'
+    end
+  end
+end

spec/mongoid/enum_spec.rb

@@ -1,4 +1,5 @@
 require 'spec_helper'
+require 'mongoid/enum/configuration'
 
 class User
   include Mongoid::Document
@@ -21,6 +22,23 @@ describe Mongoid::Enum do
       expect(klass).to have_field(field_name)
     end
 
+    it "uses prefix defined in configuration" do
+      old_field_name_prefix = Mongoid::Enum.configuration.field_name_prefix
+      Mongoid::Enum.configure do |config|
+        config.field_name_prefix = '___'
+      end
+      UserWithoutPrefix = Class.new do
+        include Mongoid::Document
+        include Mongoid::Enum
+
+        enum :status, [:awaiting_approval, :approved, :banned]
+      end
+      expect(UserWithoutPrefix).to have_field '___status'
+      Mongoid::Enum.configure do |config|
+        config.field_name_prefix = old_field_name_prefix
+      end
+    end
+
     it "is aliased" do
       expect(instance).to respond_to alias_name
       expect(instance).to respond_to :"#{alias_name}="
@@ -174,4 +192,19 @@ describe Mongoid::Enum do
       end
     end
   end
+
+  describe ".configuration" do
+    it "returns Configuration object" do
+      expect(Mongoid::Enum.configuration).to be_instance_of Mongoid::Enum::Configuration
+    end
+    it "returns same object when called multiple times" do
+      expect(Mongoid::Enum.configuration).to be Mongoid::Enum.configuration
+    end
+  end
+
+  describe ".configure" do
+    it "yields configuration if block is given" do
+      expect { |b| Mongoid::Enum.configure &b }.to yield_with_args Mongoid::Enum.configuration
+    end
+  end
 end