public void TestAddRepository()
        {
            repositoryOne.AddPackage(Helper.MockPackage("foo", "1.0"));
            Assert.AreEqual(1, repositoryComposite.Count);

            var repositoryOther = new RepositoryArray();

            repositoryOther.AddPackage(Helper.MockPackage("bar", "1.0"));
            repositoryOther.AddPackage(Helper.MockPackage("bar", "2.0"));
            repositoryOther.AddPackage(Helper.MockPackage("bar", "3.0"));
            repositoryComposite.AddRepository(repositoryOther);
            Assert.AreEqual(4, repositoryComposite.Count);
        }