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

<@UB9K6R4JH> Thanks for the reply. By `shouldContainExactly`, you mean `collections.shouldContainExactly` in <https://github.com/kotest/kotest/blob/master/doc/matchers.md|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.

Then yes, perhaps the custom matcher can work for you

I just read <https://github.com/kotest/kotest/blob/master/doc/reference.md#custom-matchers|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!

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