Comparing collection contents with ScalaTest

Question

I\'m trying to unit-test some Scala that is very collection-heavy. These collections are returned as Iterable[T], so I am interested in the contents of

Answer 1

You could try .toSeq for ordered collections and .toSet for unordered, which captures what you want as far as I understand it.

The following passes:

class Temp extends FunSuite with ShouldMatchers {
  test("1")  { Array(1, 2).toSeq should equal (List(1, 2).toSeq) }
  test("2")  { Array(2, 1).toSeq should not equal (List(1, 2).toSeq) }
  test("2b") { Array(2, 1) should not equal (List(1, 2)) }  
  test("3")  { Iterable(2, 1).toSet should equal (Iterable(1, 2).toSet) }
  test("4")  { Iterable(2, 1) should not equal (Iterable(1, 2)) }
}

BTW a Set is not ordered.

edit: To avoid removing duplicate elements, try toSeq.sorted. The following pass:

  test("5")  { Iterable(2, 1).toSeq.sorted should equal (Iterable(1, 2).toSeq.sorted) }
  test("6")  { Iterable(2, 1).toSeq should not equal (Iterable(1, 2).toSeq) }

edit 2: For unordered collections where elements cannot be sorted, you can use this method:

  def sameAs[A](c: Traversable[A], d: Traversable[A]): Boolean = 
    if (c.isEmpty) d.isEmpty
    else {
      val (e, f) = d span (c.head !=)
      if (f.isEmpty) false else sameAs(c.tail, e ++ f.tail)
    }

e.g. (note use of symbols 'a 'b 'c which have no defined ordering)

  test("7")  { assert( sameAs(Iterable(2, 1),    Iterable(1, 2)     )) }
  test("8")  { assert( sameAs(Array('a, 'c, 'b), List('c, 'a, 'b)   )) }
  test("9")  { assert( sameAs("cba",             Set('a', 'b', 'c') )) }

---

Alternative sameAs implementation:

  def sameAs[A](c: Traversable[A], d: Traversable[A]) = {
    def counts(e: Traversable[A]) = e groupBy identity mapValues (_.size)
    counts(c) == counts(d)
  }

Answer 2

Meanwhile you can use

Iterable(2, 1) should contain theSameElementsAs Iterable(1, 2)

To test the ordered set you have to convert it to a sequence.

Set(1, 2).toSeq should contain theSameElementsInOrderAs List(1, 2)