redQueue.execute("task", 100.µs) {
      log += "run@${taskFaker.nanoTime}"
    }

    taskFaker.advanceUntil(0.µs)
    assertThat(log).isEmpty()

    taskFaker.interruptCoordinatorThread()

    taskFaker.advanceUntil(0.µs)
    assertThat(log).isEmpty()

    taskFaker.assertNoMoreTasks()

    assertThat(testLogHandler.takeAll()).containsExactly(

    taskRunner.assertLockNotHeld()

    taskRunner.withLock {
      assertThat(activeThreads).isEqualTo(0)
    }
  }

  /** Unblock a waiting task thread. Used by the test thread only. */
  fun interruptCoordinatorThread() {
    taskRunner.assertLockNotHeld()
    require(currentTask == TestThreadSerialTask)

    // Queue a task to interrupt the waiting coordinator.
    serialTaskQueue +=
      object : SerialTask {