public void RequestsCorrectUrl()
            {
                var gitHubClient = Substitute.For<IGitHubClient>();
                var statisticsClient = new ObservableStatisticsClient(gitHubClient);

                statisticsClient.GetCodeFrequency("owner", "name");

                gitHubClient.Repository.Statistics.Received().GetCodeFrequency("owner", "name");
            }
            public void EnsureNonNullArguments()
            {
                var client = new ObservableStatisticsClient(Substitute.For<IGitHubClient>());

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

                Assert.Throws<ArgumentException>(() => client.GetCodeFrequency("", "name"));
                Assert.Throws<ArgumentException>(() => client.GetCodeFrequency("owner", ""));
            }