public async Task EnsuresArgumentsNotNull()
            {
                var gitHubClient = Substitute.For<IGitHubClient>();
                var client = new ObservableBlobClient(gitHubClient);

                await Assert.ThrowsAsync<ArgumentNullException>(() => client.Create(null, "name", new NewBlob()).ToTask());
                await Assert.ThrowsAsync<ArgumentException>(() => client.Create("", "name", new NewBlob()).ToTask());
                await Assert.ThrowsAsync<ArgumentNullException>(() => client.Create("owner", null, new NewBlob()).ToTask());
                await Assert.ThrowsAsync<ArgumentException>(() => client.Create("owner", "", new NewBlob()).ToTask());
                await Assert.ThrowsAsync<ArgumentNullException>(() => client.Create("owner", "name", null).ToTask());
            }
            public void PostsToCorrectUrl()
            {
                var newBlob = new NewBlob();
                var gitHubClient = Substitute.For<IGitHubClient>();
                var client = new ObservableBlobClient(gitHubClient);

                client.Create("fake", "repo", newBlob);

                gitHubClient.GitDatabase.Blob.Received().Create("fake", "repo", newBlob);
            }
            public void PostsToCorrectUrlWithRepositoryId()
            {
                var gitHubClient = Substitute.For<IGitHubClient>();
                var client = new ObservableBlobClient(gitHubClient);

                var newBlob = new NewBlob();
                client.Create(1, newBlob);

                gitHubClient.Git.Blob.Received().Create(1, newBlob);
            }