"message", handler);
        worker2.postMessage("go!");
      } else if(e.data == `${worker_2_name}-done`) {
        resolve();
      } else if(e.data == "fail") {
        reject("One opaque origin received a message from the other");
      } else {
        reject("An unexpected error occurred");
      }
    };

    let worker1 = new Worker(data_url_worker_src(channel_name, worker_1_name));
    t.add_cleanup(() => worker1.terminate());
    worker1.addEventListener("message", handler);
    worker1.postMessa