type State { Empty
  Label(text: Text) }

label(value: null, active: Bool) (answer: Text) {
  dever.task.sleep(0)
  answer = "none"
}
label(value: Text, active: true) (answer: Text) {
  pending = run(dever.task.sleep(60000))
  dever.task.sleep(0)
  answer = value + ":on"
  stop(pending)
}
label(value: Text, active: false) (answer: Text) {
  dever.task.sleep(0)
  answer = value + ":off"
}

read(value: null) (answer: Text) { dever.task.sleep(0)
  answer = "absent" }
read(value: State.Empty) (answer: Text) { dever.task.sleep(0)
  answer = "empty" }
read(value: State.Label(text)) (answer: Text) { dever.task.sleep(0)
  answer = text }

axis(left: true, right: Int < 0) (answer: Int) { dever.task.sleep(0)
  answer = 1 }
axis(left: true, right: other) (answer: Int) { dever.task.sleep(0)
  answer = 2 }
axis(left: other, right: Int < 0) (answer: Int) { dever.task.sleep(0)
  answer = 3 }
axis(left: other, right: other) (answer: Int) { dever.task.sleep(0)
  answer = 4 }

attempt(fail_now: true) () {
  pending = run(dever.task.sleep(60000))
  fail(dever.time.SleepResult.Failed("expected"))
}
attempt(fail_now: false) () {
  pending = run(dever.task.sleep(60000))
  stop(pending)
}

failed(value: dever.time.SleepResult.Done) (answer: Bool) recover("检查捕获结果") { answer = false }
failed(value: dever.time.SleepResult.Failed(message)) (answer: Bool) recover("检查捕获结果") { answer = message == "expected" }

verify() (answer: Bool) {
  original = State.Label("雪")
  missing = label(null, true)
  enabled = wait(run(label("a", true)))
  disabled = label("b", false)
  absent = read(null)
  empty = read(State.Empty)
  named = wait(run(read(original)))
  first = axis(true, -1)
  second = axis(true, 0)
  third = axis(false, -1)
  fourth = axis(false, 0)
  present_number = wait(run(number(7)))
  absent_number = wait(run(number(null)))
  observed = failed(result(attempt(true)))
  completed = failed(result(attempt(false)))
  answer = missing == "none" and enabled == "a:on" and disabled == "b:off" and absent == "absent" and empty == "empty" and named == "雪" and original == State.Label("雪") and first == 1 and second == 2 and third == 3 and fourth == 4 and present_number == 7 and absent_number == -1 and observed and not completed
}

number(value: null) (answer: Int) { dever.task.sleep(0)
  answer = -1 }
number(value: Int) (answer: Int) { dever.task.sleep(0)
  answer = value }