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import collection.immutable._
import org.scalacheck._
import Prop._
import Gen._
import Arbitrary._
import util._
object TreeSetTest extends Properties("TreeSet") {
def genTreeSet[A: Arbitrary: Ordering]: Gen[TreeSet[A]] =
for {
elements <- listOf(arbitrary[A])
} yield TreeSet(elements: _*)
implicit def arbTreeSet[A : Arbitrary : Ordering]: Arbitrary[TreeSet[A]] = Arbitrary(genTreeSet)
property("foreach/iterator consistency") = forAll { (subject: TreeSet[Int]) =>
val it = subject.iterator
var consistent = true
subject.foreach { element =>
consistent &&= it.hasNext && element == it.next
}
consistent
}
property("worst-case tree height is iterable") = forAll(choose(0, 10), arbitrary[Boolean]) { (n: Int, even: Boolean) =>
/*
* According to "Ralf Hinze. Constructing red-black trees" [http://www.cs.ox.ac.uk/ralf.hinze/publications/#P5]
* you can construct a skinny tree of height 2n by inserting the elements [1 .. 2^(n+1) - 2] and a tree of height
* 2n+1 by inserting the elements [1 .. 3 * 2^n - 2], both in reverse order.
*
* Since we allocate a fixed size buffer in the iterator (based on the tree size) we need to ensure
* it is big enough for these worst-case trees.
*/
val highest = if (even) (1 << (n+1)) - 2 else 3*(1 << n) - 2
val values = (1 to highest).reverse
val subject = TreeSet(values: _*)
val it = subject.iterator
try { while (it.hasNext) it.next; true } catch { case _: Throwable => false }
}
property("sorted") = forAll { (subject: TreeSet[Int]) => (subject.size >= 3) ==> {
subject.zip(subject.tail).forall { case (x, y) => x < y }
}}
property("contains all") = forAll { (elements: List[Int]) =>
val subject = TreeSet(elements: _*)
elements.forall(subject.contains)
}
property("size") = forAll { (elements: List[Int]) =>
val subject = TreeSet(elements: _*)
elements.distinct.size == subject.size
}
property("toSeq") = forAll { (elements: List[Int]) =>
val subject = TreeSet(elements: _*)
elements.distinct.sorted == subject.toSeq
}
property("head") = forAll { (elements: List[Int]) => elements.nonEmpty ==> {
val subject = TreeSet(elements: _*)
elements.min == subject.head
}}
property("last") = forAll { (elements: List[Int]) => elements.nonEmpty ==> {
val subject = TreeSet(elements: _*)
elements.max == subject.last
}}
property("head/tail identity") = forAll { (subject: TreeSet[Int]) => subject.nonEmpty ==> {
subject == (subject.tail + subject.head)
}}
property("init/last identity") = forAll { (subject: TreeSet[Int]) => subject.nonEmpty ==> {
subject == (subject.init + subject.last)
}}
property("take") = forAll { (subject: TreeSet[Int]) =>
val n = choose(0, subject.size).sample.get
n == subject.take(n).size && subject.take(n).forall(subject.contains)
}
property("drop") = forAll { (subject: TreeSet[Int]) =>
val n = choose(0, subject.size).sample.get
(subject.size - n) == subject.drop(n).size && subject.drop(n).forall(subject.contains)
}
property("take/drop identity") = forAll { (subject: TreeSet[Int]) =>
val n = choose(-1, subject.size + 1).sample.get
subject == subject.take(n) ++ subject.drop(n)
}
property("splitAt") = forAll { (subject: TreeSet[Int]) =>
val n = choose(-1, subject.size + 1).sample.get
val (prefix, suffix) = subject.splitAt(n)
prefix == subject.take(n) && suffix == subject.drop(n)
}
def genSliceParms = for {
tree <- genTreeSet[Int]
from <- choose(0, tree.size)
until <- choose(from, tree.size)
} yield (tree, from, until)
property("slice") = forAll(genSliceParms) { case (subject, from, until) =>
val slice = subject.slice(from, until)
slice.size == until - from && subject.toSeq == subject.take(from).toSeq ++ slice ++ subject.drop(until)
}
property("takeWhile") = forAll { (subject: TreeSet[Int]) =>
val result = subject.takeWhile(_ < 0)
result.forall(_ < 0) && result == subject.take(result.size)
}
property("dropWhile") = forAll { (subject: TreeSet[Int]) =>
val result = subject.dropWhile(_ < 0)
result.forall(_ >= 0) && result == subject.takeRight(result.size)
}
property("span identity") = forAll { (subject: TreeSet[Int]) =>
val (prefix, suffix) = subject.span(_ < 0)
prefix.forall(_ < 0) && suffix.forall(_ >= 0) && subject == prefix ++ suffix
}
property("from is inclusive") = forAll { (subject: TreeSet[Int]) => subject.nonEmpty ==> {
val n = choose(0, subject.size - 1).sample.get
val from = subject.drop(n).firstKey
subject.from(from).firstKey == from && subject.from(from).forall(_ >= from)
}}
property("to is inclusive") = forAll { (subject: TreeSet[Int]) => subject.nonEmpty ==> {
val n = choose(0, subject.size - 1).sample.get
val to = subject.drop(n).firstKey
subject.to(to).lastKey == to && subject.to(to).forall(_ <= to)
}}
property("until is exclusive") = forAll { (subject: TreeSet[Int]) => subject.size > 1 ==> {
val n = choose(1, subject.size - 1).sample.get
val until = subject.drop(n).firstKey
subject.until(until).lastKey == subject.take(n).lastKey && subject.until(until).forall(_ <= until)
}}
property("remove single") = forAll { (subject: TreeSet[Int]) => subject.nonEmpty ==> {
val element = oneOf(subject.toSeq).sample.get
val removed = subject - element
subject.contains(element) && !removed.contains(element) && subject.size - 1 == removed.size
}}
property("remove all") = forAll { (subject: TreeSet[Int]) =>
val result = subject.foldLeft(subject)((acc, elt) => acc - elt)
result.isEmpty
}
property("ordering must not be null") =
throws(classOf[NullPointerException])(TreeSet.empty[Int](null))
}
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