taskFaker.runTasks()
    client.listener.assertFailure(IOException::class.java, "source is closed")
    assertThat(client.webSocket!!.send("Hello!")).isFalse()
  }

  @Test
  fun socketClosedDuringMessageKillsWebSocket() {
    server.source.close()
    assertThat(client.webSocket!!.send("Hello!")).isTrue()
    taskFaker.runTasks()

 * deterministic.
 *
 * This class ensures that at most one thread is running at a time. This is initially the JUnit test
 * thread, which yields its execution privilege while calling [runTasks], [runNextTask], or
 * [advanceUntil]. These functions don't return until the task threads are all idle.
 *
 * Task threads release their execution privilege in these ways:
 *

    blueQueue.execute("blue task", 200.µs) {
      log += "blue:run@${taskFaker.nanoTime}"
    }
    assertThat(taskFaker.executeCallCount).isEqualTo(1)

    // Nothing to do.
    taskFaker.runTasks()
    assertThat(log).isEmpty()

    // At 100.µs, the coordinator runs the red task and starts a thread for the new coordinator.
    taskFaker.advanceUntil(100.µs)
    assertThat(log).containsExactly("red:run@100000")