The Tor Browser / file revision

 /*

  * Any copyright is dedicated to the Public Domain.

  * http://creativecommons.org/licenses/publicdomain/

  */

 /* A stock watcher function. */

 var watcherCount;

 function watcher(id, oldval, newval) { watcherCount++; return newval; }

 /* Create an object with a JavaScript setter. */

 var setterCount;

 var o = { w:2, set x(v) { setterCount++; } };

 /*

  * Put the object in dictionary mode, so that JSObject::putProperty will 

  * mutate its shapes instead of creating new ones.

  */

 delete o.w;

 /*

  * Place a watchpoint on the property. The watchpoint structure holds the

  * original JavaScript setter, and a pointer to the shape.

  */

 o.watch('x', watcher);

 /*

  * Replace the accessor property with a value property. The shape's setter

  * should become a non-JS setter, js_watch_set, and the watchpoint

  * structure's saved setter should be updated (in this case, cleared).

  */

 Object.defineProperty(o, 'x', { value:3,

                                 writable:true,

                                 enumerable:true,

                                 configurable:true });

 /*

  * Assign to the property. This should trigger js_watch_set, which should

  * call the handler, and then see that there is no JS-level setter to pass

  * control on to, and return.

  */

 watcherCount = setterCount = 0;

 o.x = 3;

 assertEq(watcherCount, 1);

 assertEq(setterCount, 0);

 reportCompare(true, true);