public void AddInnerBag_Works_Correctly()
{
var a = new Bag("A");
var b = new Bag("B");
var c = new Bag("C");
a.AddInnerBag(b, 1);
a.AddInnerBag(c, 2);
Assert.That(a.OuterBags.Count(), Is.Zero);
Assert.That(a.InnerBags, Is.EquivalentTo(new [] { (b, 1), (c, 2) }));