added greater than or equal to node

lib/arel/attributes/attribute.rb

@@ -24,6 +24,10 @@ def maximum
       def average
         Nodes::Avg.new [self], Nodes::SqlLiteral.new('avg_id')
       end
+
+      def gteq right
+        Nodes::GreaterThanOrEqual.new self, right
+      end
     end
 
     class String  < Attribute; end

lib/arel/nodes.rb

@@ -2,6 +2,7 @@
 require 'arel/nodes/equality'
 require 'arel/nodes/or'
 require 'arel/nodes/and'
+require 'arel/nodes/greater_than_or_equal'
 
 require 'arel/nodes/in'
 require 'arel/nodes/lock'

lib/arel/nodes/greater_than_or_equal.rb

+module Arel
+  module Nodes
+    class GreaterThanOrEqual < Arel::Nodes::Binary
+    end
+  end
+end

lib/arel/visitors/to_sql.rb

@@ -109,6 +109,10 @@ def visit_Arel_Nodes_TableAlias o
         "#{visit o.relation} #{quote_table_name o.name}"
       end
 
+      def visit_Arel_Nodes_GreaterThanOrEqual o
+        "#{visit o.left} >= #{visit o.right}"
+      end
+
       def visit_Arel_Nodes_StringJoin o
         "#{visit o.left} #{visit o.right}"
       end

spec/arel/attributes/attribute_spec.rb

@@ -3,6 +3,22 @@
 module Arel
   module Attributes
     describe 'attribute' do
+      describe '#gteq' do
+        it 'should create a GreaterThanOrEqual node' do
+          relation = Table.new(:users)
+          relation[:id].gteq(10).should be_kind_of Nodes::GreaterThanOrEqual
+        end
+
+        it 'should generate >= in sql' do
+          relation = Table.new(:users)
+          mgr = relation.project relation[:id]
+          mgr.where relation[:id].gteq(10)
+          mgr.to_sql.should be_like %{
+            SELECT "users"."id" FROM "users" WHERE "users"."id" >= 10
+          }
+        end
+      end
+
       describe '#average' do
         it 'should create a AVG node' do
           relation = Table.new(:users)