Highlight "double" in specs

Author: tpope

autoload/rails.vim

@@ -3521,7 +3521,7 @@ function! s:BufSyntax()
         endif
       elseif t=~ '^spec\>'
         syn keyword rubyRailsTestMethod describe context it its specify it_should_behave_like before after subject fixtures controller_name helper_name
-        syn keyword rubyRailsTestMethod violated pending expect mock mock_model stub_model
+        syn keyword rubyRailsTestMethod violated pending expect double mock mock_model stub_model
         syn match rubyRailsTestMethod '\.\@<!\<stub\>!\@!'
         if t !~ '^spec-model\>'
           syn match   rubyRailsTestControllerMethod  '\.\@<!\<\%(get\|post\|put\|delete\|head\|process\|assigns\)\>'