如何在MVC中測試控制器類？

Question

我正在根據Model-View-Controller模式在Swift中構建一個簡單的iOS應用程序。我可以通過給它輸入數據並根據我的期望斷言輸出結果來測試Model類。但我想知道如何測試Controller類？

看來，如果我想測試Controller類，測試邏輯將會複雜得多。有沒有測試Controller類的標準方法？

Answer 1

請勿測試您的UIViewController s。發生在他們身上的很多事情你沒有看到和/或無法控制。相反，在其他對象（如查看模型）中保留儘可能多的邏輯，而不是您的UIViewController。然後，您可以測試您的視圖模型，就像測試模型一樣。

編輯：

你會怎樣想構建你的UIViewController S和測試模型&視圖模型：

從這個代碼的主要外賣是：

1. 使用Dependency Injection
2. 在Release中給類賦予真正的依賴關係，並在測試中僞造依賴項

視圖控制器

// this class is super simple, so there's hardly any reason to test it now. 
class SomeViewController: UIViewController { 
    @IBOutlet weak var someLabel: UILabel! 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     // we give the *real* user accessor in the view controller 
     let viewModel = SomeViewModel(userAccessor: DBUserAccessor()) 
     someLabel.text = viewModel.welcomeMessage 
    } 
} 

用戶模型

struct User { 
    var name: String 
} 

用戶訪問器

這是一些依賴你的視圖模型的需求。在發佈期間（在您的View Controller中）給出一個真實的。在測試過程中給出一個假的，以便你可以控制它。

protocol UserAccessor { 
    var currentUser: User? { get } 
} 

// since we're using the fake version of this class to test the view model, you might want to test this class on its own 
// you would do that using the same principles that I've shown (dependency injection). 
class DBUserAccessor: UserAccessor { 
    var currentUser: User? { 
     // some real implementation that's used in your app 
     // get the user from the DB 
     return User(name: "Samantha") // so not really this line, but something from CoreData, Realm, etc. 
    } 
} 

class FakeUserAccessor: UserAccessor { 
    // some fake implementation that's used in your tests 
    // set it to whatever you want your tests to "see" as the current User from the "DB" 
    var currentUser: User? 
} 

視圖模型

這是實際生活的邏輯，你想測試。

class SomeViewModel { 
    let userAccessor: UserAccessor 

    init(userAccessor: UserAccessor) { 
     self.userAccessor = userAccessor 
    } 

    var welcomeMessage: String { 
     if let username = self.username { 
      return "Welcome back, \(username)" 
     } else { 
      return "Hello there!" 
     } 
    } 

    var username: String? { 
     return userAccessor.currentUser?.name 
    } 
} 

測試

最後，你想怎麼對它進行測試。

class SomeViewModelTest: XCTestCase { 
    func testWelcomeMessageWhenNotLoggedIn() { 
     let userAccessor = FakeUserAccessor() 
     let viewModel = SomeViewModel(userAccessor: userAccessor) // we give the *fake* user accessor to the view model in tests 
     userAccessor.currentUser = nil // set the fake UserAccessor to not have a user "logged in" 

     // assert that the view model, which uses whatever you gave it, gives the correct message 
     XCTAssertEqual(viewModel.welcomeMessage, "Hello there!") 
    } 

    func testWelcomeMessageWhenLoggedIn() { 
     let userAccessor = FakeUserAccessor() 
     let viewModel = SomeViewModel(userAccessor: userAccessor) 
     userAccessor.currentUser = User(name: "Joe") // this time, the use is "logged in" 

     XCTAssertEqual(viewModel.welcomeMessage, "Welcome back, Joe") // and we get the correct message 
    } 
}