public async Task EnsuresNonNullArguments()
            {
                var client = new ObservableIssuesLabelsClient(Substitute.For <IGitHubClient>());

                Assert.Throws <ArgumentNullException>(() => client.RemoveAllFromIssue(null, "name", 42));
                Assert.Throws <ArgumentNullException>(() => client.RemoveAllFromIssue("owner", null, 42));

                Assert.Throws <ArgumentException>(() => client.RemoveAllFromIssue("", "name", 42));
                Assert.Throws <ArgumentException>(() => client.RemoveAllFromIssue("owner", "", 42));
            }
            public void DeletesCorrectUrlWithRepositoryId()
            {
                var connection   = Substitute.For <IConnection>();
                var gitHubClient = new GitHubClient(connection);
                var client       = new ObservableIssuesLabelsClient(gitHubClient);

                client.RemoveAllFromIssue(1, 42);

                connection.Received().Delete(Arg.Is <Uri>(u => u.ToString() == "repositories/1/issues/42/labels"));
            }