How do you assert matchers on nested object contents? Something like capturing slots in MockK. E.g. ...

# kotest

[Lukasz Kalnik]

How do you assert matchers on nested object contents? Something like capturing slots in MockK.
E.g. I have an object like this:

Success(Either.Left(IOError(cause=com.google.gson.stream.MalformedJsonException)))

I want to assert certain things:
• that the contents of Success is of type Left
• that the contents of Left is of type IOError
• that the cause is of type MalformedJsonException

[sam]

Are you using arrow ?

[Lukasz Kalnik]

Yes

[sam]

And Success here is a kotlin Result ?

[Lukasz Kalnik]

No

[Lukasz Kalnik]

It's a custom class from Retrofit I guess

[Lukasz Kalnik]

But my question is more general

[sam]

ok, well for things like Arrow, we offer matchers that will smart cast as well as return the contained value

[Lukasz Kalnik]

What about the `IOError`'s cause property type?

[sam]

val v = either.shouldBeLeft()
v shouldBe "whatever"

or

either.shouldBeLeft().shouldBe("whatever")

[Lukasz Kalnik]

Can I somehow extract it?

[Lukasz Kalnik]

And assert that its type is MalformedJsonException?

[Lukasz Kalnik]

I don't want to check equality, I just want to check the type of the cause property

[sam]

either.shouldBeLeft().cause.shouldBeInstanceOf<MalformedJsonException>()

[Lukasz Kalnik]

ah ok, thanks!