How can I test sealed classes in Kotlin? for example I have ```sealed class LoginResult { object...

# android

[Remon Shehata]

How can I test sealed classes in Kotlin?
for example I have

sealed class LoginResult {
    object Success : LoginResult()
    object WrongCredentials : LoginResult()
    data class InvalidData(val error: ErrorType) : LoginResult()
}

sealed class ErrorType {
    object EmptyEmail : ErrorType()
    object InvalidEmailFormat : ErrorType()
    object EmptyPassword : ErrorType()
}

how can I assert that I got the result of InvalidData with the error of EmptyEmail ?

[Landry Norris]

I would check if

error is EmptyEmail

[Remon Shehata]

I can do assertTrue(result is LoginResult.InvalidData)

[Remon Shehata]

How can I check that the error is empty email?

[Remon Shehata]

I can do val x = result as LoginResult.InvalidData
assertTrue(x.error is ErrorType.EmptyEmail)

[Remon Shehata]

but I am sure there is a better way

[Rick Clephas]

You can use assertIs to type check the result. This will smart cast result so you can directly access error

[Rick Clephas]

assertIs<LoginResult.InvalidDate>(result)
assertIs<ErrorType.EmptyEmail>(result.error)

https://kotlinlang.org/api/latest/kotlin.test/kotlin.test/assert-is.html

[Remon Shehata]

Unresolved reference: assertIs

[Remon Shehata]

this should be part of Kotlin right?

[Rick Clephas]

It's part of the kotlin.test library. You should add the following dependency to your tests:

testImplementation(kotlin("test"))

[Remon Shehata]

Thanks a lot man, you have been a great help