René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Incorrect finance Validation Logic","articleBody":"## Incorrect finance Validation Logic (possible bug)\nHi,  \nwhile reviewing the `finance.py` validators (ISIN, CUSIP, SEDOL), I found that the validators contain several issues, and I’d like to confirm whether this is a bug or if I’m missing something.\n\nReference to my mutation-testing analysis:  \nhttps://github.com/Bolest-oci/mutation-testing/issues/35\n\n### F.e ISIN\nThe official ISIN format is **two uppercase letters, nine alphanumeric characters, and one check digit** (12 characters total).  \nHowever, the current validator seems incomplete:\n\n- The Luhn checksum is implemented incorrectly and never computed.\n- The format is not enforced (first two characters should be uppercase letters, last must be a digit).\n- Lowercase letters and invalid characters are accepted.\n- It does not verify that the first two letters form a country code (optional, but usually expected).\n\nI'm thinking of submitting a PR with a fix, but I'm asking first to make sure I'm not missing something.  \nThanks!  ","author":{"url":"https://github.com/lexendo","@type":"Person","name":"lexendo"},"datePublished":"2025-11-25T01:50:08.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/440/validators/issues/440"}