Ios 在UI测试目标中使用Alamofire

下面使用Alamofire的代码片段在iOS应用程序中运行良好，但在iOS UI测试目标中不起作用

let configuration = NSURLSessionConfiguration.defaultSessionConfiguration()
configuration.HTTPAdditionalHeaders =   Alamofire.Manager.defaultHTTPHeaders
manager = Alamofire.Manager(configuration: configuration)
manager!.request(.GET, "https://www.google.com")
        .responseString { response in
            print(response.request)  // original URL request
            print(response.response) // URL response
            print(response.result)   // result of response serialization
            print("HTML: \(response.result.value)")
    }

在UI测试目标中永远不会调用完成处理程序

let configuration = NSURLSessionConfiguration.defaultSessionConfiguration()
configuration.HTTPAdditionalHeaders =   Alamofire.Manager.defaultHTTPHeaders
manager = Alamofire.Manager(configuration: configuration)
manager!.request(.GET, "https://www.google.com")
        .responseString { response in
            print(response.request)  // original URL request
            print(response.response) // URL response
            print(response.result)   // result of response serialization
            print("HTML: \(response.result.value)")
    }

如果我将.progress块添加到请求中，这将得到执行，但completionHandler仍然没有得到执行

有人能告诉我我可能做错了什么吗