It depends what you mean by "better".

Maybe Python has lousy spec but as I recall, the documentation does include a BNF breakdown of what Python is.

A test suite can be good for a lot of things BUT it cannot be a specification, it cannot be even sort-of a specification. Test suites only "prove a negative", only prove that an application won't do X. A specification is at least a rough assertion of a positive, that a language does follow this pattern.