type Problem { error Text(message: Text)
 error Number(value: Int) }

type LocalResult { Done
 error Failed(values: List<Stream<Int>>) }

work(delay: Int) () { dever.task.sleep(delay) }

cpu() () pure {}

duration() (value: Int) { dever.task.sleep(0)
 value = 0 }

badText(delay: Int) () { dever.task.sleep(delay)
 fail(Problem.Text("worker")) }

badNumber() () { fail(Problem.Number(42)) }

badDuration() (value: Int) { dever.task.sleep(0)
 fail(Problem.Text("argument")) }

failedGroup() () { pool = group(2)
 run(pool, work(60000))
 run(pool, badText(0))
 wait(pool) }

failedAdmission() () { pool = group(1)
 run(pool, badNumber())
 run(pool, work(60000))
 wait(pool) }

failedArgument() () { pool = group(2)
 run(pool, work(60000))
 run(pool, work(badDuration())) }

invalidGroup() () { pool = group(0)
 wait(pool) }

emptyGroups() () { wait(group(2))
 stop(group(1)) }

localParent(flag: true) () {
 pool = group(1)
 run(pool, cpu())
 wait(pool)
}
localParent(flag: false) () { fail(LocalResult.Failed([])) }

localHandled(value: LocalResult.Done) (answer: Bool) recover("观察局部错误") { answer = false }
localHandled(value: LocalResult.Failed(values)) (answer: Bool) recover("观察局部错误") { answer = length(values) == 0 }

verifyLocal() (answer: Bool) { localParent(true)
 answer = localHandled(result(localParent(false))) }

verify() (answer: Bool) {
 emptyGroups()
 pool = group(2)
 run(pool, cpu())
 run(pool, work(0))
 run(pool, work(duration()))
 wait(pool)
 pool = group(1)
 run(pool, work(60000))
 stop(pool)
 answer = true
}