Ask HN: Is there a legislative equivalent to unit tests

Taking a look at the similarities between drafting legislation and computer programming, it strikes me as odd that legislation seems to have no corresponding notion to unit tests or integration tests.

The closest I can see (from a laypersons view) would be case law as one could theoretically look back at old decisions and determine if the same decisions would be made under new legislation, but that's not how it works. It's way more nuanced and case law actually sets legal precedents.

Is there a more direct corollary between unit testing and legislation?