unitTestAPIService404

unitTestAPIService404.swift

import XCTest
import Foundation

class APIService {
    let defaultSession = URLSession(configuration: .default)
    typealias APIServiceCompletionHandler = (Int?) -> Void
    var urlString: String?
    init(urlString: String) {
        self.urlString = urlString
    }
    
    func fetch( completionHandler: @escaping APIServiceCompletionHandler) {
        
        
        if let urlString = urlString, let url = URL(string: urlString ) {
            
            let request = URLRequest(url: url)
            let dataTask = self.defaultSession.dataTask(with: request, completionHandler: { (data, response, error) -> Void in
                if let httpResponse = response as? HTTPURLResponse {
                    completionHandler(httpResponse.statusCode)
                }
            })
            dataTask.resume()
            
        }
        
    }
}

class Mock404Service: APIService {
    override func fetch(completionHandler: @escaping APIService.APIServiceCompletionHandler) {
        completionHandler(404)
    }
}


class Interactor: NSObject {
    var service: APIService = APIService(urlString: "")
    var statusCode: Int?
    var statusString: String?
    func getSomthing(callback: (() -> Void)) {
        service.fetch { (statusCode) in
            self.statusCode = statusCode
            if statusCode == 404 {
                self.statusString = "Status Code is 404"
            }
        }
    }
}

func test404() {
    let interactor = Interactor()
    interactor.service = Mock404Service(urlString: "")
    interactor.getSomthing {
        XCTAssertEqual(interactor.statusCode, 404)
        XCTAssertEqual(interactor.statusString, "Status Code is 404")
    }
    
}


test404()