Kotlin 回调单元测试

Question

我正在为我的应用编写单元测试。我需要测试一个处理我的应用程序内部登录的函数。此登录处理程序使用回调，在登录完成时发出通知。这是我的登录处理程序

class LoginManager {

private var auth: FirebaseAuth = Firebase.auth

fun loginWithEmail(
        email: String,
        password: String,
        loginCallback: LoginCallback
) {
    auth.signInWithEmailAndPassword(email, password).addOnCompleteListener { loginTask ->
        if (loginTask.isSuccessful) {
            auth.currentUser?.let { user ->
                loginCallback.onLoginSuccess(user)
                return@addOnCompleteListener
            }
        }

        loginCallback.onLoginFailure(loginTask.exception)
    }
} }

LoginCallback 是一个简单的接口

interface LoginCallback {
fun onLoginSuccess(user: FirebaseUser)
fun onLoginFailure(error: Exception?) }

我需要测试 loginWithEmail 函数。在我的测试中，我尝试使用此代码

Handler(getMainLooper()).post {
        var firebaseUser: FirebaseUser? = null
        val loginCallback = object : LoginCallback {
            override fun onLoginSuccess(user: FirebaseUser) {
                firebaseUser = user
            }

            override fun onLoginFailure(error: Exception?) {
                //No action needed
            }

        }

        val loginManager = LoginManager(loginCallback)

        loginManager.loginWithEmail(EXISTING_EMAIL_ADDRESS, CORRECT_PASSWORD)
        Thread.sleep(5000)
        assert(firebaseUser != null)
    }

    shadowOf(getMainLooper()).idle()

但是回调永远不会被调用。我也尝试使用 ArgumentCaptor

Handler(getMainLooper()).post {
        val captor =  ArgumentCaptor.forClass(LoginCallback::class.java)
        val loginManager = LoginManager()
        loginManager.loginWithEmail(EXISTING_EMAIL_ADDRESS, CORRECT_PASSWORD, captor.capture())
    }

    shadowOf(getMainLooper()).idle()

但是使用此代码，我收到此错误 java.lang.NullPointerException: captor.capture() must not be null

有没有办法测试我的功能？