public void UnionTest(int[] a, int[] b, int[] expected)
{
var listA = new VSArray <int>(a);
var listB = new VSArray <int>(b);
// Create new list, don't modify original
var list2 = listA.Union(listB);
Assert.That(listA, Is.EqualTo(a.ToVSArray()));
Assert.That(listB, Is.EqualTo(b.ToVSArray()));
Assert.That(list2, Is.EqualTo(expected.ToVSArray()));
// Modify original (in-place)
listA.UnionWith(listB);
Assert.That(listA, Is.EqualTo(expected.ToVSArray()));
Assert.That(listA, Is.EqualTo(list2));
}