public void RequestsCorrectUrlWithRepositoryId()
            {
                var gitHubClient = Substitute.For<IGitHubClient>();
                var client = new ObservableReferencesClient(gitHubClient);

                client.GetAllForSubNamespace(1, "heads");

                gitHubClient.Received().Git.Reference.GetAllForSubNamespace(1, "heads");
            }
            public void EnsuresNonNullArguments()
            {
                var client = new ObservableReferencesClient(Substitute.For<IGitHubClient>());

                Assert.Throws<ArgumentNullException>(() => client.GetAllForSubNamespace(null, "name", "heads"));
                Assert.Throws<ArgumentNullException>(() => client.GetAllForSubNamespace("owner", null, "heads"));
                Assert.Throws<ArgumentNullException>(() => client.GetAllForSubNamespace("owner", "name", null));

                Assert.Throws<ArgumentNullException>(() => client.GetAllForSubNamespace(1, null));

                Assert.Throws<ArgumentException>(() => client.GetAllForSubNamespace("", "name", "heads"));
                Assert.Throws<ArgumentException>(() => client.GetAllForSubNamespace("owner", "", "heads"));
                Assert.Throws<ArgumentException>(() => client.GetAllForSubNamespace("owner", "name", ""));

                Assert.Throws<ArgumentException>(() => client.GetAllForSubNamespace(1, ""));
            }