private SellingCompany CreateSellingCompany(User user)
 {
     return new SellingCompany
         {
             SellingCompanyId = 1,
             Abbreviation = "Test",
             CompanyName = "Test Company",
             ManagedBy = new List<User> {user}
         };
 }
        public SellingCompanyTreeViewRoot BuildTreeViewForUser(User user)
        {
            var sellingCompaniesForUser = user.SellingCompanies;

            var treeViewRoot = new SellingCompanyTreeViewRoot
            {
                Items = new List<SellingCompanyTreeViewItem>()
            };

            foreach (var sellingCompany in sellingCompaniesForUser)
            {
                treeViewRoot.Items.Add(BuildTreeViewForCompany(sellingCompany));
            }

            return treeViewRoot;
        }