I've also been wondering about this. It doesn't seem to do anything if I use the standard (check-expect) and (run-tests) forms. <div class="gmail_quote">On Sun, Nov 27, 2011 at 8:17 PM, Mark Engelberg <<a href="mailto:mark.engelberg@gmail.com">mark.engelberg@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">In the latest version of Racket, I see a menu item to disable and enable tests. What testing library does this work with? The htdp testing library, rackunit, something else? Thanks, Mark _________________________________________________ For list-related administrative tasks: <a href="http://lists.racket-lang.org/listinfo/users" target="_blank">http://lists.racket-lang.org/listinfo/users</a> </blockquote></div>