bpo-40334: Fix test_peg_parser to actually use the old parser by lysnikolaou · Pull Request #19778 · python/cpython
Now that the default parser is the new PEG parser, ast.parse uses
it, which means that we don't actually test something in
test_peg_parser. This PR introduces a new kwarg oldparser for
_peg_parser.parse_string for specifying that a string needs to
be parsed with the old parser. This kwarg is used in the tests to
actually compare the ASTs the new parser generates with those
generated by the old parser.
Closes we-like-parsers/cpyhton#93.