public async Task EnsuresNonNullArguments()
            {
                var client = new RepositoryBranchesClient(Substitute.For<IApiConnection>());
                var newContexts = new List<string>() { "test" };

                await Assert.ThrowsAsync<ArgumentNullException>(() => client.AddRequiredStatusChecksContexts(null, "repo", "branch", newContexts));
                await Assert.ThrowsAsync<ArgumentNullException>(() => client.AddRequiredStatusChecksContexts("owner", null, "branch", newContexts));
                await Assert.ThrowsAsync<ArgumentNullException>(() => client.AddRequiredStatusChecksContexts("owner", "repo", null, newContexts));
                await Assert.ThrowsAsync<ArgumentNullException>(() => client.AddRequiredStatusChecksContexts("owner", "repo", "branch", null));

                await Assert.ThrowsAsync<ArgumentNullException>(() => client.AddRequiredStatusChecksContexts(1, null, newContexts));
                await Assert.ThrowsAsync<ArgumentNullException>(() => client.AddRequiredStatusChecksContexts(1, "branch", null));

                await Assert.ThrowsAsync<ArgumentException>(() => client.AddRequiredStatusChecksContexts("", "repo", "branch", newContexts));
                await Assert.ThrowsAsync<ArgumentException>(() => client.AddRequiredStatusChecksContexts("owner", "", "branch", newContexts));
                await Assert.ThrowsAsync<ArgumentException>(() => client.AddRequiredStatusChecksContexts("owner", "repo", "", newContexts));

                await Assert.ThrowsAsync<ArgumentException>(() => client.AddRequiredStatusChecksContexts(1, "", newContexts));
            }
            public void RequestsTheCorrectUrlWithRepositoryId()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new RepositoryBranchesClient(connection);
                var newContexts = new List<string>() { "test" };
                const string previewAcceptsHeader = "application/vnd.github.loki-preview+json";

                client.AddRequiredStatusChecksContexts(1, "branch", newContexts);

                connection.Received()
                    .Post<IReadOnlyList<string>>(Arg.Is<Uri>(u => u.ToString() == "repositories/1/branches/branch/protection/required_status_checks/contexts"), Arg.Any<IReadOnlyList<string>>(), previewAcceptsHeader);
            }