SwiftTask chain失敗の検証

gistfile1.swift

NSLog("0. start")

self.request1()
    .success { _ -> Task<Progress, Int, Bool> in
        NSLog("1-2. request1 callback")
        return self.request2()
    }
    .success { _ in
        NSLog("2-2. request2 callback")
    }

---------------------------------------------------

func request1() -> Task<Progress, Int, NSError> {
    return Task<Progress, Int, NSError> { progress, fulfill, reject, configure in
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(1.0 * Double(NSEC_PER_SEC))), dispatch_get_main_queue()) {
            NSLog("1-1. request1 done")
            fulfill(1)
        }
    }
}

func request2() -> Task<Progress, Int, Bool> {
    return Task<Progress, Int, Bool> { progress, fulfill, reject, configure in
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(1.0 * Double(NSEC_PER_SEC))), dispatch_get_main_queue()) {
            NSLog("2-1. request2 done")
            fulfill(1)
        }
    }
}

enum WrappedError {
    case ByTask1(NSError)
    case ByTask2(Bool)
    case Cancelled
}

func task1() -> Task<(),(),NSError> {
    return Task<(),(),NSError>{ (progress, fulfill, reject, configure) in
        fulfill()
    }
}

func task2() -> Task<(),(),Bool> {
    return Task<(),(),Bool>{ (progress, fulfill, reject, configure) in
        fulfill()
    }
}

private extension Task {
    func _mapError(f: Error -> WrappedError) -> Task<Progress, Value, WrappedError>
    {
        return self.failure({ (error:Error?, isCancelled) -> Task<Progress, Value, WrappedError> in
            if let error = error {
                return Task<Progress, Value, WrappedError>(error: f(error))
            }
            else {
                return Task<Progress, Value, WrappedError>(error: .Cancelled)
            }
        })
    }
}

task1()._mapError(WrappedError.ByTask1).success {
    return task2()._mapError(WrappedError.ByTask2)
}.on (failure: { (error, isCancelled) in
    guard let error = error else { return }
    switch error {
    case let .ByTask1(err):
        print(err)
    case let .ByTask2(flag):
        print(flag)
    case .Cancelled:
        ()
    }
})