public void UnionWithTest3()
{
var bag = new HashBag <int> {
1, 2, 3, 4
};
var l = new List <int> {
5, 6
};
bag.UnionWith(l);
Assert.Equal(6, bag.Count);
Assert.Equal(new[] { 1, 2, 3, 4, 5, 6 }, bag);
}
