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

                Assert.Throws<ArgumentNullException>(() => client.GetAllForIssue(null, "name", 1));
                Assert.Throws<ArgumentNullException>(() => client.GetAllForIssue("owner", null, 1));
                Assert.Throws<ArgumentNullException>(() => client.GetAllForIssue(null, "name", 1, ApiOptions.None));
                Assert.Throws<ArgumentNullException>(() => client.GetAllForIssue("owner", null, 1, ApiOptions.None));
                Assert.Throws<ArgumentNullException>(() => client.GetAllForIssue("owner", "name", 1, null));

                Assert.Throws<ArgumentException>(() => client.GetAllForIssue("", "name", 1));
                Assert.Throws<ArgumentException>(() => client.GetAllForIssue("owner", "", 1));
                Assert.Throws<ArgumentException>(() => client.GetAllForIssue("", "name", 1, ApiOptions.None));
                Assert.Throws<ArgumentException>(() => client.GetAllForIssue("owner", "", 1, ApiOptions.None));
            }
            public async Task RequestsCorrectUrlWithRepositoryId()
            {
                var connection = Substitute.For<IConnection>();
                var gitHubClient = new GitHubClient(connection);
                var client = new ObservableIssuesLabelsClient(gitHubClient);

                client.GetAllForIssue(1, 42);

                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels"), Args.EmptyDictionary, null);
            }
            public async Task RequestsCorrectUrlWithApiOptionsWithRepositoryId()
            {
                var connection = Substitute.For<IConnection>();
                var gitHubClient = new GitHubClient(connection);
                var client = new ObservableIssuesLabelsClient(gitHubClient);

                var options = new ApiOptions
                {
                    PageCount = 1,
                    StartPage = 1,
                    PageSize = 1
                };

                client.GetAllForIssue(1, 42, options);

                connection.Received().Get<List<Label>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/issues/42/labels"), Arg.Is<Dictionary<string, string>>(d => d.Count == 2), null);
            }