Add :encode_with for proper YAML serialization

lib/arel/nodes/sql_literal.rb

@@ -5,6 +5,10 @@ module Arel
       include Arel::Predications
       include Arel::AliasPredication
       include Arel::OrderPredications
+
+      def encode_with(coder)
+        coder.scalar = self.to_s
+      end
     end
 
     class BindParam < SqlLiteral

test/nodes/test_sql_literal.rb

@@ -1,4 +1,5 @@
 require 'helper'
+require 'yaml'
 
 module Arel
   module Nodes
@@ -56,6 +57,13 @@ module Arel
           @visitor.accept(node).must_be_like %{ (foo = 1 AND foo = 2) }
         end
       end
+
+      describe 'serialization' do
+        it 'serializes into YAML' do
+          yaml_literal = SqlLiteral.new('foo').to_yaml
+          assert_equal('foo', YAML.load(yaml_literal))
+        end
+      end
     end
   end
 end