@Test
public void noViolationsForValidCart() throws Exception {

    requiredProductsInCart("900901", "900902", "900903", "900904");
    RegisterNew command = givenCartRegistrationCommand("900901", "900902", "900903", "900904");
    ValidationResult result = validator.validate(command);
    Assertions.assertThat(result.getViolations()).isEmpty();
}