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import scala.collection.immutable._
object Test extends App {
// test that ListSet.tail does not use a builder
// we can't test for O(1) behavior, so the best we can do is to
// check that ls.tail always returns the same instance
val ls = ListSet.empty[Int] + 1 + 2
if(ls.tail ne ls.tail)
println("ListSet.tail should not use a builder!")
// class that always causes hash collisions
case class Collision(value:Int) { override def hashCode = 0 }
// create a set that should have a collison
val x = HashSet.empty + Collision(0) + Collision(1)
if(x.getClass.getSimpleName != "HashSetCollision1")
println("HashSet of size >1 with collisions should use HashSetCollision")
// remove the collision again by removing all but one element
val y = x - Collision(0)
if(y.getClass.getSimpleName != "HashSet1")
println("HashSet of size 1 should use HashSet1" + y.getClass)
}
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