public void CreateRole_Null_Test() { //get all the roles from the db List <Role> previousRoles = rolesBL.GetAllRoles().ToList <Role>(); //add a new role to the db string roleName = null; rolesBL.AddRole(roleName); List <Role> expectedRoles = new List <Role>(); expectedRoles.AddRange(previousRoles); //add the previous Roles to the list List <Role> actualRoles = rolesBL.GetAllRoles().ToList <Role>(); //check if expected roles with the actual roles are equal AreListsEqual(expectedRoles, actualRoles); }