@Before
    public void setUp() {
        grammar = new GrammarParser();
        grammar.productionRules.add(new Rule("A", "a"));
        grammar.productionRules.add(new Rule("B", "bb"));
        grammar.productionRules.add(new Rule("C", "BB"));
        grammar.productionRules.add(new Rule("D", "DD"));
        parser = new InitialisationParser(grammar);
    }