// Let the event loop process a bit before crashing. if (shouldDelay) { let shouldCrashNow = false; let thr = Components.classes["@mozilla.org/thread-manager;1"] .getService().currentThread; thr.dispatch({ run: () => { shouldCrashNow = true; } }, Components.interfaces.nsIThread.DISPATCH_NORMAL); while (!shouldCrashNow) { thr.processNextEvent(true); } } // now actually crash CrashTestUtils.crash(crashType);