Comment by HelloNurse

PEG parsing is likely to squash some grammar ambiguities in unexpected ways, making a test suite a very good idea; but we shouldn't forget that this kind of failure can only happen starting from an ambiguous grammar specification, so the work of taming PEG precedence or combinator behaviour is not an additional burden of the technology but an additional tool to correct the grammar to become less ambiguous, an alternative to rewriting it in unnatural, verbose and complex ways.