antlr-mega-tutorial | companion repository of the ANTLR Mega Tutorial | Learning library

I want to test my lexer/parser in a Python Unittest. For that purpose I'd like antlr to fail with an Exception everytime anything is out of order. What is the most elegant way to achieve this?

I have read the ANTLR Mega Tutorial, there they write an ErrorListener which overrides syntaxError() to save the last offending symbol and then in the end, they check if any offending symbol was encountered.

I saw that there are different ErrorStrategy classes and BailErrorStrategy sounds like this is what I need. But then I read How can I fail on first syntax error in a python ANTLR generated parser while keeping the error message? which says this strategy doesn't alway throw an Exception.

My best idea so far is to throw an Exception in ErrorListener.syntxError():

I've seen many examples of the implementation of lexical modes across this site as well as other places, like the Definitive Guide to ANTLR4. Before writing my own lexer grammar with lexical modes, I just wanted to try an example. So I copied the example from the ANTLR Mega Tutorial: