//
// message Person {
// optional long id = -1;
// }
@Test public void should_create_error_if_field_index_is_negative() {
MessageField field = xtext.find("id", MessageField.class);
validator.checkTagNumberIsGreaterThanZero(field);
String message = "Expected field number.";
verify(messageAcceptor).acceptError(message, field, MESSAGE_FIELD__INDEX, INSIGNIFICANT_INDEX,
INVALID_FIELD_TAG_NUMBER_ERROR);
}