[STORE] Changed that document_type method returns nil when no klass is set

Author: karmi

Diff for: elasticsearch-persistence/lib/elasticsearch/persistence/repository/naming.rb

@@ -20,7 +20,7 @@ def index_name=(name)
         end
 
         def document_type
-          klass.to_s.underscore
+          klass ? klass.to_s.underscore : nil
         end
 
         def __get_klass_from_type(type)

Diff for: elasticsearch-persistence/test/unit/repository_naming_test.rb

@@ -86,9 +86,11 @@ def self.class
     end
 
     context "document_type" do
-      should "default to klass" do
-        assert_equal '', subject.document_type
+      should "be nil when no klass is set" do
+        assert_equal nil, subject.document_type
+      end
 
+      should "default to klass" do
         subject.klass Foobar
         assert_equal 'foobar', subject.document_type
       end