Swift 单元测试 : async

Question

我在正确进行单元测试时遇到问题，我想检查它的数据是否在我的结构中，我可以让我的函数打印出有多少项目但是测试失败了，因为期望没有出现后退。我知道我需要使用

XCTAssertNotNil(self.players.countPlayers)

这是我的函数标题

public func getPlayer(completionHandler: @escaping (Data?, URLResponse?, Error?) -> (Swift.Void)
    ) throws{
    let jsonUrl: String = "http://api.football-data.org/v1/teams/78/players"
    //print(jsonUrl)
    // NSURL sessions allow us to download data using HTTP for APIs
    // a NSURL which contains a correct resourse
    guard let leagueURL = NSURL(string: jsonUrl)else{
        print("error creating string")
        throw JSONError.InvalidURL(jsonUrl)
    }
    let task = URLSession.shared.dataTask(with: leagueURL as URL) {data, responce, error in

            do {
                let json = try JSONSerialization.jsonObject(with: data!, options: JSONSerialization.ReadingOptions.mutableContainers) as!   NSDictionary
                self.searchLeague = []
                for item in json["players"] as! [[String: AnyObject]]{
                    guard let name = ((item["name"]!) as? String) else{
                        throw JSONError.InvalidKey("invalid player name")
                    }
                    guard let position = ((item["position"]!) as? String) else{
                        throw JSONError.InvalidKey("invalid player position")
                    }
                    let jerseyNumber = ( ((item["jerseyNumber"]!) as? String) ?? ("No Assigned jersey number") )

                    guard let dateOfBirth = ((item["dateOfBirth"]!) as? String) else{
                        throw JSONError.InvalidKey("invalid player DOB")
                    }
                    guard let nationality = ((item["nationality"]!) as? String) else{
                        throw JSONError.InvalidKey("invalid player DOB")
                    }
                    let marketvalue = ( ((item["marketValue"]!) as? String) ?? ("Market value info not available"))
                    self.searchPlayer.append(Player(name: name, position: position, jerseyNumber: jerseyNumber, dateOfBirth: dateOfBirth, nationality: nationality, marketValue: marketvalue))
                }
            }catch{
                print("error thrown: \(error)")
            }
        print("Num of Players \(self.searchPlayer.count)")
        }
    task.resume()

}

和我的测试

    func testGetPlayers(){
         let expectations = expectation(description: "Wait for exception")
         try! self.players.getPlayer{_,_,_ in
          expectations.fulfill()
    }
    waitForExpectations(timeout: 5) { error in
    }
}

Answer 1

您已经成功地证明了为什么单元测试是个好主意。

您在 getPlayer 方法中发现了一个严重的错误 - 您从未调用完成处理程序。

您应该使用 getPlayer 方法中不同位置的适当参数调用 completionHandler 闭包，具体取决于您是成功处理数据还是遇到错误。