public void DifferenceTest()
{
for (int i = 0; i < 4; i++)
{
set.Add(i);
}
ArraySet set1 = new ArraySet();
for (int i = 2; i < 6; i++)
{
set1.Add(i);
}
Assert.AreEqual("{0, 1}", set.Difference(set1).ToString());
}