I believe our `shouldContainExactly` might fit your usecase, but if you really want to create a cust...

# kotest

[LeoColman]

I believe our shouldContainExactly might fit your usecase, but if you really want to create a custom matcher, it's not very hard:

[JP]

@LeoColman Thanks for the reply. By shouldContainExactly, you mean collections.shouldContainExactly in matchers, and in order to use this I would have to make the data structure be a subclass of Kotlin’s Collection, right?
Currently my usecase is simple, I’m just practicing Kotlin with problem solving via leetcode, and leetcode has some predefined data structure classes such as:

class ListNode(var `val`: Int) {
    var next: ListNode? = null
}

Then I wanted to make custom functions for testing locally with kotest, where I have written a function like

fun linkedListOf(vararg elements: Int): ListNode

where it creates a singly linked list with a syntax like linkedListOf(1, 2, 3) and returns the head ListNode.

[LeoColman]

Ah, I see, you're the one creating the linkedlist, not using an usual LinkedList.

[LeoColman]

Then yes, perhaps the custom matcher can work for you

[LeoColman]

Did you understand how to create it?

[JP]

I just read Custom Matchers, I think I understood how to create it. I first tried to implement Kotlin’s Collection myself and then used kotest’s shouldContainExactly matcher. Next I’ll try to create this custom matchers. Thanks for the info!

[JP]

BTW, it seems that in the link of Custom Matchers reference there’s a minor typo, where it’s written Result instead of MatcherResult ?

[LeoColman]

You're correct. I fixed that name