Ensure the attribute exists before returning its value

lib/capybara/webkit/node.rb

@@ -12,7 +12,11 @@ module Capybara::Webkit
       if name == 'checked' || name == 'disabled' || name == 'multiple'
         value == 'true'
       else
-        value
+        if invoke("hasAttribute", name) == 'true'
+          value
+        else
+          nil
+        end
       end
     end
 

spec/driver_spec.rb

@@ -773,7 +773,7 @@ describe Capybara::Webkit::Driver do
       end
 
       it "does not modify the selected attribute of a new selection" do
-        monkey_option['selected'].should be_empty
+        monkey_option['selected'].should be_nil
       end
 
       it "returns the old value when a reset button is clicked" do

src/capybara.js

@@ -64,6 +64,10 @@ Capybara = {
     }
   },
 
+  hasAttribute: function(index, name) {
+    return this.nodes[index].hasAttribute(name);
+  },
+
   path: function(index) {
     return "/" + this.getXPathNode(this.nodes[index]).join("/");
   },