Hi All, suppose that I have 2 lists `List<A>` & `List<B>` and a function `f: (A, B) ...

# kotest

[Xuc Xiem]

Hi All, suppose that I have 2 lists List<A> & List<B> and a function f: (A, B) -> Boolean. I want to assert that for every element in listA there's only one element in listB so that f(a, b) is true.

listA.forEach { a ->
  listB
    .filter { f(a, it) }
    .shouldBeSingleton()
}

I want to print out the element a that makes the assertion fail. How could I do that?

[sam]

Could do something like,

listA.forEach { a ->
   listB.forOne { b ->
    f(a, b) shouldBe true
   }
}