I tried to implement the tests and ran into two problems:

Any implementation of the Queue comparison function involves extracting values from the first and second queues and comparing elements with each other, or using a comparison through transformation into a list. The problem here is that the first and second queues are the same queue.
In function comparator

(a: Queue, b: Queue) => Boolean

if we extract from queue a, we also extract from queue b.

the only solution I've found is limited check dequeue equality by size before and after extract elements.

  private def getQueueEq[A: Eq, Q <: QueueSource[IO, A]](implicit ticker: Ticker): Eq[Q] = {
    (x: Q, y: Q) =>
      {
        unsafeRun {
          for {
            xSizeBeforeTake <- x.size
            ySizeBeforeTake <- y.size
            _ <- if (xSizeBeforeTake > 0) x.tryTakeN(xSizeBeforeTake.some) else IO.pure(List())
            xSizeAfterTake <- x.size
            ySizeAfterTake <- y.size
          } yield xSizeBeforeTake === ySizeBeforeTake && xSizeAfterTake == ySizeAfterTake
        } match {
          case Outcome.Succeeded(a) => a
          case Outcome.Errored(e) =>
            throw new Exception(s"Run error: $e")
          case Outcome.Canceled() =>
            throw new Exception("Canceled")
        }
      }.get
  }

I don't know how to implement Contravariant tests, because it's implement in QueueSink that implement only offer methods. I'm not found any way to compare it or transform it in comparable type.

Uh oh!

Laws testing for queue functor instances #1618

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