I believe our

shouldContainExactly

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

@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

.

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

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!

You're correct. I fixed that name