def test_infinite_loop(self):
        Grammar("""
            digits = digit+
            int = digits
            digit = ~"[0-9]"
            number = int
            main = number
            """)
Smoke-test a grammar that was causing infinite loops while building.
dataset/ETHPy150Open erikrose/parsimonious/parsimonious/tests/test_grammar.py/GrammarTests.test_infinite_loop