Adding put_conditional support and spec. Fixes error no Const

Module::YAML when running single simpledb specs.

lib/fog/aws/requests/simpledb/put_attributes.rb

@@ -29,6 +29,15 @@ module Fog
           )
         end
 
+        def put_conditional(domain_name, item_name, attributes, expected_attributes = {})
+          request({
+            'Action'      => 'PutAttributes',
+            'DomainName'  => domain_name,
+            :parser       => Fog::Parsers::AWS::SimpleDB::Basic.new(@nil_string),
+            'ItemName' => item_name
+          }.merge!(encode_attributes(attributes, {}, expected_attributes)))
+        end
+
       end
 
       class Mock
@@ -41,6 +50,28 @@ module Fog
           )
         end
 
+        def put_conditional(domain_name, item_name, attributes, expected_attributes = {})
+          response = Excon::Response.new
+          if @data[:domains][domain_name]
+            expected_attributes.each do |ck, cv|
+              if @data[:domains][domain_name][item_name][ck] != cv
+                response.status = 409
+                raise(Excon::Errors.status_error({:expects => 200}, response))
+              end
+            end
+            attributes.each do |key, value|
+              @data[:domains][domain_name][item_name] ||= {}
+              @data[:domains][domain_name][item_name][key.to_s] = value
+            end
+            response.status = 200
+            response.body = {
+              'BoxUsage'  => Fog::AWS::Mock.box_usage,
+              'RequestId' => Fog::AWS::Mock.request_id
+            }
+          response
+        end
+      end
+
       end
     end
   end

lib/fog/aws/simpledb.rb

@@ -73,9 +73,17 @@ module Fog
 
         private
 
-        def encode_attributes(attributes, replace_attributes = [])
+        def encode_attributes(attributes, replace_attributes = {}, expected_attributes = {})
           encoded_attributes = {}
           if attributes
+
+            expected_attributes.keys.each_with_index do |exkey, index|
+              for value in Array(expected_attributes[exkey])
+                encoded_attributes["Expected.#{index}.Name"] = exkey.to_s
+                encoded_attributes["Expected.#{index}.Value"] = sdb_encode(value)
+              end
+            end
+
             index = 0
             for key in attributes.keys
               for value in Array(attributes[key])
@@ -132,7 +140,7 @@ module Fog
               :aws_access_key_id  => @aws_access_key_id,
               :hmac               => @hmac,
               :host               => @host,
-              :version            => '2007-11-07'
+              :version            => '2009-04-15'
             }
           )
 

lib/fog/credentials.rb

@@ -1,3 +1,4 @@
+require 'yaml'
 module Fog
   class << self
 

spec/aws/requests/simpledb/put_attributes_spec.rb

@@ -18,6 +18,23 @@ describe 'SimpleDB.put_attributes' do
       actual.body['BoxUsage'].should be_a(Float)
     end
 
+    it 'conditional put should succeed' do
+      actual = AWS[:sdb].put_conditional(@domain_name, 'foo', { 'version' => '1' }, { 'version' => nil })
+      actual = AWS[:sdb].put_conditional(@domain_name, 'foo', { 'version' => '2' }, { 'version' => '1' })
+      actual.body['RequestId'].should be_a(String)
+      actual.body['BoxUsage'].should be_a(Float)
+    end
+
+    it 'conditional put should raise Conflict error' do
+      actual = AWS[:sdb].put_conditional(@domain_name, 'foo', { 'version' => '2' })
+      actual.body['RequestId'].should be_a(String)
+      actual.body['BoxUsage'].should be_a(Float)
+
+      lambda {
+        actual = AWS[:sdb].put_conditional(@domain_name, 'foo', { 'version' => '2' }, { 'version' => '1' })
+      }.should raise_error(Excon::Errors::Conflict)
+    end
+
   end
   describe 'failure' do