public void AddRegisteredUserToEvent_Added_NotFail_Test() { var context = new MyEventsContext(); int registeredUserId = context.RegisteredUsers.First().RegisteredUserId; var eventDefinition = context.EventDefinitions.Include("RegisteredUsers") .Where(e => !e.RegisteredUsers.Any(r => r.RegisteredUserId == registeredUserId)).First(); int eventDefinitionId = eventDefinition.EventDefinitionId; int expected = eventDefinition.RegisteredUsers.Count() + 1; IRegisteredUserRepository target = new RegisteredUserRepository(); target.AddRegisteredUserToEvent(registeredUserId, eventDefinitionId); var contextAfter = new MyEventsContext(); var eventDefinitionAfter = contextAfter.EventDefinitions.Include("RegisteredUsers").First(e => e.EventDefinitionId == eventDefinitionId); int actual = eventDefinitionAfter.RegisteredUsers.Count(); Assert.AreEqual(expected, actual); }