}
    assertThat(taskFaker.executeCallCount).isEqualTo(1)

    // Running the red task starts another thread, so the two can run in parallel.
    taskFaker.runNextTask()
    assertThat(log).containsExactly("red:starting@0")
    assertThat(taskFaker.executeCallCount).isEqualTo(2)

    // Next the blue task starts.
    taskFaker.runNextTask()
    assertThat(log).containsExactly(
      "red:starting@0",