object Test {
  def main(args: Array[String]): Unit = {
    val test = scala.reflect.internal.util.WeakHashSetTest
    test.checkEmpty
    test.checkPlusEquals
    test.checkPlusEqualsCollisions
    test.checkRehashing
    test.checkRehashCollisions
    test.checkFindOrUpdate
    test.checkMinusEquals
    test.checkMinusEqualsCollisions
    test.checkClear
    test.checkIterator
    test.checkIteratorCollisions

    // This test is commented out because it relies on gc behavior which isn't reliable enough in an automated environment
    // test.checkRemoveUnreferencedObjects
  }
}

// put the main test object in the same package as WeakHashSet because
// it uses the package private "diagnostics" method
package scala.reflect.internal.util {

  object WeakHashSetTest {
    // a class guaranteed to provide hash collisions
    case class Collider(x : String) extends Comparable[Collider] with Serializable {
      override def hashCode = 0
      def compareTo(y : Collider) = this.x compareTo y.x
    }

    // basic emptiness check
    def checkEmpty: Unit = {
      val hs = new WeakHashSet[String]()
      assert(hs.size == 0)
      hs.diagnostics.fullyValidate
    }

    // make sure += works
    def checkPlusEquals: Unit = {
      val hs = new WeakHashSet[String]()
      val elements = List("hello", "goodbye")
      elements foreach (hs += _)
      assert(hs.size == 2)
      assert(hs contains "hello")
      assert(hs contains "goodbye")
      hs.diagnostics.fullyValidate
    }

    // make sure += works when there are collisions
    def checkPlusEqualsCollisions: Unit = {
      val hs = new WeakHashSet[Collider]()
      val elements = List("hello", "goodbye") map Collider
      elements foreach (hs += _)
      assert(hs.size == 2)
      assert(hs contains Collider("hello"))
      assert(hs contains Collider("goodbye"))
      hs.diagnostics.fullyValidate
    }

    // add a large number of elements to force rehashing and then validate
    def checkRehashing: Unit = {
      val size = 200
      val hs = new WeakHashSet[String]()
      val elements = (0 until size).toList map ("a" + _)
      elements foreach (hs += _)
      elements foreach {i => assert(hs contains i)}
      hs.diagnostics.fullyValidate
    }

    // make sure rehashing works properly when the set is rehashed
    def checkRehashCollisions: Unit = {
      val size = 200
      val hs = new WeakHashSet[Collider]()
      val elements = (0 until size).toList map {x => Collider("a" + x)}
      elements foreach (hs += _)
      elements foreach {i => assert(hs contains i)}
      hs.diagnostics.fullyValidate
    }

    // test that unreferenced objects are removed
    // not run in an automated environment because gc behavior can't be relied on
    def checkRemoveUnreferencedObjects: Unit = {
      val size = 200
      val hs = new WeakHashSet[Collider]()
      val elements = (0 until size).toList map {x => Collider("a" + x)}
      elements foreach (hs += _)
      // don't throw the following into a retained collection so gc
      // can remove them
      for (i <- 0 until size) {
        hs += Collider("b" + i)
      }
      System.gc()
      Thread.sleep(1000)
      assert(hs.size == 200)
      elements foreach {i => assert(hs contains i)}
      for (i <- 0 until size) {
        assert(!(hs contains Collider("b" + i)))
      }
      hs.diagnostics.fullyValidate
    }

    // make sure findOrUpdate returns the originally entered element
    def checkFindOrUpdate: Unit = {
      val size = 200
      val hs = new WeakHashSet[Collider]()
      val elements = (0 until size).toList map {x => Collider("a" + x)}
      elements foreach {x => assert(hs findEntryOrUpdate x eq x)}
      for (i <- 0 until size) {
        // when we do a lookup the result should be the same reference we
        // original put in
        assert(hs findEntryOrUpdate(Collider("a" + i)) eq elements(i))
      }
      hs.diagnostics.fullyValidate
    }

    // check -= functionality
    def checkMinusEquals: Unit = {
      val hs = new WeakHashSet[String]()
      val elements = List("hello", "goodbye")
      elements foreach (hs += _)
      hs -= "goodbye"
      assert(hs.size == 1)
      assert(hs contains "hello")
      assert(!(hs contains "goodbye"))
      hs.diagnostics.fullyValidate
    }

    // check -= when there are collisions
    def checkMinusEqualsCollisions: Unit = {
      val hs = new WeakHashSet[Collider]
      val elements = List(Collider("hello"), Collider("goodbye"))
      elements foreach (hs += _)
      hs -= Collider("goodbye")
      assert(hs.size == 1)
      assert(hs contains Collider("hello"))
      assert(!(hs contains Collider("goodbye")))
      hs -= Collider("hello")
      assert(hs.size == 0)
      assert(!(hs contains Collider("hello")))
      hs.diagnostics.fullyValidate
    }

    // check that the clear method actually cleans everything
    def checkClear: Unit = {
      val size = 200
      val hs = new WeakHashSet[String]()
      val elements = (0 until size).toList map ("a" + _)
      elements foreach (hs += _)
      hs.clear()
      assert(hs.size == 0)
      elements foreach {i => assert(!(hs contains i))}
      hs.diagnostics.fullyValidate
    }

    // check that the iterator covers all the contents
    def checkIterator: Unit = {
      val hs = new WeakHashSet[String]()
      val elements = (0 until 20).toList map ("a" + _)
      elements foreach (hs += _)
      assert(elements.iterator.toList.sorted == elements.sorted)
      hs.diagnostics.fullyValidate
    }

    // check that the iterator covers all the contents even when there is a collision
    def checkIteratorCollisions: Unit = {
      val hs = new WeakHashSet[Collider]
      val elements = (0 until 20).toList map {x => Collider("a" + x)}
      elements foreach (hs += _)
      assert(elements.iterator.toList.sorted == elements.sorted)
      hs.diagnostics.fullyValidate
    }
  }
}