public async Task EnsuresNonNullArguments()
            {
                var teams = new TeamsClient(Substitute.For<IApiConnection>());

                await Assert.ThrowsAsync<ArgumentNullException>(() => teams.GetAll(null));
                await Assert.ThrowsAsync<ArgumentNullException>(() => teams.GetAll("orgName", null));
            }

            public void RequestsTheCorrectlUrl()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new TeamsClient(connection);

                client.Get(1);

                connection.Received().Get<Team>(Arg.Is<Uri>(u => u.ToString() == "teams/1"), null);
            }

            public void RequestsTheCorrectUrl()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new TeamsClient(connection);

                client.GetAll("orgName");

                connection.Received().GetAll<Team>(Arg.Is<Uri>(u => u.ToString() == "orgs/orgName/teams"));
            }

            public void EnsuresNonNullArguments()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new TeamsClient(connection);
                var team = new NewTeam("superstars");

                Assert.Throws<ArgumentNullException>(() => client.Create(null, team));
                Assert.Throws<ArgumentException>(() => client.Create("", team));
                Assert.Throws<ArgumentNullException>(() => client.Create("name", null));
            }

            public void RequestsTheCorrectUrl()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new TeamsClient(connection);
                var team = new UpdateTeam("Octokittens");

                client.UpdateTeam(1, team);

                connection.Received().Patch<Team>(Arg.Is<Uri>(u => u.ToString() == "teams/1"), team);
            }

            public async Task EnsuresNonNullArguments()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new TeamsClient(connection);

                AssertEx.Throws<ArgumentNullException>(async () => await
                    client.CreateTeam("", new NewTeam("superstars")));
                AssertEx.Throws<ArgumentException>(async () => await
                    client.CreateTeam("name", null));
            }

            public void EnsuresNonEmptyLogin()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new TeamsClient(connection);

                AssertEx.Throws<ArgumentException>(() => client.IsMember(1, ""));
            }

            public async Task RequestsTheCorrectUrl()
            {
                var connection = Substitute.For<IApiConnection>();

                var client = new TeamsClient(connection);

                await client.AddMembership(1, "user");

                connection.Received().Put<Dictionary<string, string>>(
                    Arg.Is<Uri>(u => u.ToString() == "teams/1/memberships/user"),
                    Args.Object);
            }

            public void RequestsTheCorrectUrl()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new TeamsClient(connection);

                client.GetAllForCurrent();

                connection.Received().GetAll<Team>(
                    Arg.Is<Uri>(u => u.ToString() == "user/teams"),
                    Args.ApiOptions);
            }

            public async Task EnsuresNonNullOrEmptyArguments()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new TeamsClient(connection);

                // Check owner arguments.
                await Assert.ThrowsAsync<ArgumentNullException>(() => client.RemoveRepository(1, null, "repoName"));
                await Assert.ThrowsAsync<ArgumentException>(() => client.RemoveRepository(1, "", "repoName"));

                // Check repo arguments.
                await Assert.ThrowsAsync<ArgumentNullException>(() => client.RemoveRepository(1, "ownerName", null));
                await Assert.ThrowsAsync<ArgumentException>(() => client.RemoveRepository(1, "ownerName", ""));
            }

            public void AddOrUpdatePermission()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new TeamsClient(connection);
                var newPermission = new RepositoryPermissionRequest(Permission.Admin);

                client.AddRepository(1, "org", "repo", newPermission);

                connection.Connection.Received().Put<HttpStatusCode>(Arg.Is<Uri>(u => u.ToString() == "teams/1/repos/org/repo"), Arg.Any<object>(), "", "application/vnd.github.ironman-preview+json");
            }

            public async Task EnsuresNonNullOrEmptyLogin()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new TeamsClient(connection);

                await Assert.ThrowsAsync<ArgumentNullException>(() => client.RemoveMembership(1, null));
                await Assert.ThrowsAsync<ArgumentException>(() => client.RemoveMembership(1, ""));
            }

            public void EnsuresNonNullLogin()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new TeamsClient(connection);

                Assert.ThrowsAsync<ArgumentNullException>(() => client.GetMembership(1, null));
            }

            public async Task AllowsEmptyBody()
            {
                var connection = Substitute.For<IConnection>();

                var apiConnection = new ApiConnection(connection);

                var client = new TeamsClient(apiConnection);

                await client.AddMembership(1, "user");

                connection.Received().Put<Dictionary<string, string>>(
                    Arg.Is<Uri>(u => u.ToString() == "teams/1/memberships/user"),
                    Arg.Is<object>(u => u == RequestBody.Empty));
            }

            public void EnsureNonNullOrg()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new TeamsClient(connection);

                Assert.ThrowsAsync<ArgumentException>(() => client.AddRepository(1, null, "Repo Name"));
            }

            public void EnsureNonNullRepo()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new TeamsClient(connection);

                AssertEx.Throws<ArgumentException>(() => client.AddRepository(1, "org name", null));

            }

            public void RequestsTheCorrectUrl()
            {
                var connection = Substitute.For<IApiConnection>();
                var client = new TeamsClient(connection);
                client.GetRepositories(1);

                connection.Received().GetAll<Repository>(Arg.Is<Uri>(u => u.ToString() == "teams/1/repos/"));
            }