public async Task Cannot_add_SiteManager_when_it_already_exists()
        {
            const string SITE_MANAGER_ID = "EMP1";
            const string FIRST_NAME      = "First Name";
            const string LAST_NAME       = "Last Name";
            const string MOBILE          = "0718958874";

            using (var context = new ProcurementDbContext(ContextOptions))
            {
                SiteManagersController siteManagersController = new SiteManagersController(context);

                SiteManager siteManager = new SiteManager {
                    StaffId = SITE_MANAGER_ID, FirstName = FIRST_NAME, LastName = LAST_NAME, MobileNo = MOBILE
                };;

                try
                {
                    await siteManagersController.PostSiteManager(siteManager);
                }
                catch (Exception exception)
                {
                    Assert.NotNull(exception);
                    return;
                }

                Assert.True(false);
            }
        }
        public async Task Can_add_new_SiteManager_when_it_not_existing()
        {
            const string SITE_MANAGER_ID = "EMP4";
            const string FIRST_NAME      = "First Name";
            const string LAST_NAME       = "Last Name";
            const string MOBILE          = "0718958874";

            using (var context = new ProcurementDbContext(ContextOptions))
            {
                SiteManagersController siteManagersController = new SiteManagersController(context);

                SiteManager siteManager = new SiteManager {
                    StaffId = SITE_MANAGER_ID, FirstName = FIRST_NAME, LastName = LAST_NAME, MobileNo = MOBILE
                };

                var result = await siteManagersController.PostSiteManager(siteManager);

                var viewResult   = Assert.IsType <ActionResult <SiteManager> >(result);
                var actionResult = Assert.IsType <CreatedAtActionResult>(viewResult.Result);
                var model        = Assert.IsType <SiteManager>(actionResult.Value);
                Assert.Equal(SITE_MANAGER_ID, model.StaffId);
            }
        }