public void Should_return_list_of_credentials()
        {
            const string username1 = "*****@*****.**";
            const string username2 = "*****@*****.**";
            const string password  = "******";

            var identity = _identityDirectory.CreateIdentity();

            _identityStore.AddCredentials(identity, username1, password);
            _identityStore.AddCredentials(identity, username2, password, false, new[] { "contacts" });

            var credentials = _identityStore.GetCredentials(identity).ToList();

            Assert.AreEqual(2, credentials.Count());

            var credential1 = credentials.FirstOrDefault(c => c.Username == username1);
            var credential2 = credentials.FirstOrDefault(c => c.Username == username2);

            Assert.IsNotNull(credential1);
            Assert.AreEqual(identity, credential1.Identity);

            Assert.IsNotNull(credential2);
            Assert.AreEqual(identity, credential2.Identity);
            Assert.AreEqual(1, credential2.Purposes.Count);
            Assert.AreEqual("contacts", credential2.Purposes[0]);
        }