模拟 iOS Firebase Auth 登录方法

Question

这个问题有点类似于Swift 中的 Mock 第三方类 (Firebase)，但根据对它的答案，不同的地方足以保证提出一个新问题。

我正在尝试模拟Auth / FIRAuth方法signIn(withEmail email: String, password: String, completion: AuthDataResultCallback?)并且在尝试模拟AuthDataResultCallback对象时遇到了困难，主要是因为它有一个User属性，我也想嘲笑。 不幸的是，我无法创建自己的User或Auth对象，因为它们已被标记为在 Swift 中没有可用的初始化程序。

我有一个对象（我们称之为UserAuthenticationRepository ）负责执行用户身份验证和数据库读取。 我想向其中注入一个 Firebase auth 对象以在后台执行这些操作，但是由于我想测试这个存储库对象，所以我希望在进行单元测试时能够注入一个 Firebase 模拟对象。

我想要做的是这样的事情（这个问题稍微简化了）：

import FirebaseAuth

protocol FirebaseUserType {
    var uid: String { get }
}

extension User: FirebaseUserType {}

protocol FirebaseAuthDataResultType {
    var user: FirebaseUserType { get }
}

extension AuthDataResult: FirebaseAuthDataResultType {
    var user: FirebaseUserType {
        // This is where I'm running into problems because AuthDataResult expects a User object, 
        // which I also use in the UserAuthenticationRepository signIn(withEmail:) method
    }
}

protocol FirebaseAuthenticationType {
    func signIn(withEmail email: String, password: String, completion: ((FirebaseAuthDataResultType?, Error?) -> Void)?)
}

extension Auth: FirebaseAuthenticationType {
    func signIn(withEmail email: String, password: String, completion: ((FirebaseAuthDataResultType?, Error?) -> Void)?) {
        let completion = completion as AuthDataResultCallback?
        signIn(withEmail: email, password: password, completion: completion)
    }
}

protocol UserAuthenticationType {
    func loginUser(emailAddress: String, password: String) -> Observable<User>
}

class UserAuthenticationRepository: UserAuthenticationType {
    private let authenticationService: FirebaseAuthenticationType
    private let disposeBag = DisposeBag()

    init(authenticationService: FirebaseAuthenticationType = Auth.auth()) {
        self.authenticationService = authenticationService
    }

    func loginUser(emailAddress: String, password: String) -> Observable<User> {
        return .create { [weak self] observer in
            self?.authenticationService.signIn(withEmail: emailAddress, password: password, completion: { authDataResult, error in
                if let error = error {
                    observer.onError(error)
                } else if let authDataResult = authDataResult {
                    observer.onNext(authDataResult.user)
                }
            })
            return Disposables.create()
        }
    }

如上所述，当我尝试扩展AuthDataResult以符合我的FirebaseAuthDataResultType协议时遇到了问题。 有可能做我想做的事吗？ 在测试UserAuthenticationRepository时，我最终想在我的 Firebase 身份验证服务中传回一个uid字符串。

Answer 1

我最终能够找到一种方法来模拟我所需的 Firebase Auth对象，但我不得不诉诸于 Firebase User对象的子类化，向它添加在测试期间使用的新属性（不能直接创建User对象或改变其属性），然后创建一个符合FirebaseAuthDataResultType的结构，该结构在测试期间使用MockUser对象进行初始化。 我最终需要的协议和扩展如下：

protocol FirebaseAuthDataResultType {
    var user: User { get }
}

extension AuthDataResult: FirebaseAuthDataResultType {}

typealias FirebaseAuthDataResultTypeCallback = (FirebaseAuthDataResultType?, Error?) -> Void

protocol FirebaseAuthenticationType {
    func signIn(withEmail email: String, password: String, completion: FirebaseAuthDataResultTypeCallback?)
    func signOut() throws
    func addStateDidChangeListener(_ listener: @escaping AuthStateDidChangeListenerBlock) -> AuthStateDidChangeListenerHandle
    func removeStateDidChangeListener(_ listenerHandle: AuthStateDidChangeListenerHandle)
}

extension Auth: FirebaseAuthenticationType {
    func signIn(withEmail email: String, password: String, completion: FirebaseAuthDataResultTypeCallback?) {
        let completion = completion as AuthDataResultCallback?
        signIn(withEmail: email, password: password, completion: completion)
    }
}

下面是模拟对象：

class MockUser: User {
    let testingUID: String
    let testingEmail: String?
    let testingDisplayName: String?

    init(testingUID: String,
         testingEmail: String? = nil,
         testingDisplayName: String? = nil) {
        self.testingUID = testingUID
        self.testingEmail = testingEmail
        self.testingDisplayName = testingDisplayName
    }
}

struct MockFirebaseAuthDataResult: FirebaseAuthDataResultType {
    var user: User
}

带有存根的模拟 Firebase 身份验证服务的实例：

class MockFirebaseAuthenticationService: FirebaseAuthenticationType {
    typealias AuthDataResultType = (authDataResult: FirebaseAuthDataResultType?, error: Error?)
    var authDataResultFactory: (() -> (AuthDataResultType))?

    func signIn(withEmail email: String, password: String, completion: FirebaseAuthDataResultTypeCallback?) {
      // Mock service logic goes here
    }

    // ...rest of protocol functions
}

用法（使用RxSwift和RxTest ）：

func testLoginUserReturnsUserIfSignInSuccessful() {
    let firebaseAuthService = MockFirebaseAuthenticationService()
    let expectedUID = "aM1RyjpaZcQ4EhaUvDAeCnla3HX2"
    firebaseAuthService.authDataResultFactory = {
        let user = MockUser(testingUID: expectedUID)
        let authDataResult = MockFirebaseAuthDataResult(user: user)
        return (authDataResult, nil)
    }

    let sut = UserSessionRepository(authenticationService: firebaseAuthService)
    let userObserver = testScheduler.createObserver(User.self)

    sut.loginUser(emailAddress: "john@gmail.com", password: "123456")
       .bind(to: userObserver)
       .disposed(by: disposeBag)

    testScheduler.start()

    let user = userObserver.events[0].value.element as? MockUser

    // Assert MockUser properties, events, etc.
}

如果有人对如何实现这一点有更好的想法，请告诉我！