public void testFail() {
   Resource root = resourceInModel("x rdf:type A");
   AssemblerGroup g = AssemblerGroup.create();
   g.implementWith(resource("A"), new ShantAssemble());
   try {
     g.open(root);
     fail("shouldn't get past exception");
   } catch (AssemblerException e) {
     AssemblerGroup.Frame frame =
         new AssemblerGroup.Frame(resource("x"), resource("A"), ShantAssemble.class);
     assertEquals(listOfOne(frame), e.getDoing());
   }
 }