public void minusTest()
{
Collections.Set<int> s = new Collections.Set<int>();
Collections.Set<int> s2 = new Collections.Set<int>();
int[] a = { 1, 5, 6, 9 };
int[] b = { 1, 4, 7, 9 };
for (int i = 0; i < a.Length; i++)
{
s += (a[i]);
s2 += (b[i]);
}
for (int i = 0; i < a.Length; i++)
{
s -= (a[i]);
s2 -= (b[i]);
}
Assert.AreEqual(0, s.size());
Assert.AreEqual(0, s2.size());
}
