[STORE] Short-circuit the operation and return false when the model is not valid

Closes elastic#289

Author: kkirsche

elasticsearch-persistence/lib/elasticsearch/persistence/model/store.rb

@@ -102,6 +102,9 @@ def destroy(options={})
           # @return [Hash] The Elasticsearch response as a Hash
           #
           def update(attributes={}, options={})
+            unless options.delete(:validate) == false
+              return false unless valid?
+            end
             raise DocumentNotPersisted, "Object not persisted: #{self.inspect}" unless persisted?
 
             run_callbacks :update do

elasticsearch-persistence/test/unit/model_store_test.rb

@@ -311,6 +311,43 @@ def valid?; false; end;
         assert subject.update( {}, { script: 'EXEC' } )
       end
 
+      should "not update an invalid model" do
+        subject.expects(:persisted?).returns(true)
+        subject.expects(:id).returns('abc123').at_least_once
+
+        @gateway
+          .expects(:update)
+          .never
+
+        subject.instance_eval do
+          def valid?; false; end;
+        end
+
+        assert ! subject.update
+        assert ! subject.persisted?
+      end
+
+      should "skip the validation with the :validate option" do
+        subject.expects(:persisted?).returns(true)
+        subject.expects(:id).returns('abc123').at_least_once
+
+        @gateway
+          .expects(:update)
+          .with do |object, options|
+            assert_equal subject, object
+            assert_equal nil, options[:id]
+            true
+          end
+          .returns({'_id' => 'abc123'})
+
+        subject.instance_eval do
+          def valid?; false; end;
+        end
+
+        assert subject.update validate: false
+        assert subject.persisted?
+      end
+
       should "pass the options to gateway" do
         subject.expects(:persisted?).returns(true)