public static IEnumerable <Customer> GetCustomers()
            {
                var repository = new CustomerReadRepository(new DataContext(new PersistenceConfiguration(RepositoryTestsHelper.ConnectionString)));
                var result     = repository.ListAsync(null, null, null).Result;

                return(result);
            }
            public static Customer CreateCustomer(Guid id, string name, string description, string source)
            {
                // prepare
                var writeRepository = new CustomerWriteRepository(new DataContext(new PersistenceConfiguration(RepositoryTestsHelper.ConnectionString)));
                var readRepository  = new CustomerReadRepository(new DataContext(new PersistenceConfiguration(RepositoryTestsHelper.ConnectionString)));

                // create
                var customer = new Customer(id, name, description, source);
                IEnumerable <Customer> customers = new List <Customer>()
                {
                    customer
                };

                foreach (var item in customers)
                {
                    writeRepository.CreateAsync(item).GetAwaiter().GetResult();
                }

                // result
                var result = readRepository.GetAsync(customer.Id).Result;

                return(result);
            }