Terminology correction needed - Visa, Mastercard, AMEX are not card issuers - your bank is a card issuer. Mastercard, Visa, etc are card networks.

Am I missing something or, without more tests, could AMEX just be returned for any card number with a length of 15 digits?

No random tests in Haskell.

Fork with added random tests.

Enabled in this fork

• Node 18. should be enabled

• Test.expect should be aborted

• Assertions that do not test anything should be removed, like this one:

  Test.expect("randomCase", "Random case function expected");

• Description should be language-agnostic

• Write a function that will randomly upper and lower characters in a string

  should be

  Write a function that will randomly convert characters in a string to their lowercased and uppercased form

Enabled in this fork

Approved

python new test framework is required. updated in this fork

Description should be language-agnostic

Approved

python new test frame work

C#: method name should be PascalCase (Please refer to implementation of backward compatibility here )

Any card number with a length of 15 starting with 3 is AMEX, not just 34 or 37.

Same for Discover: length of 16 starting with 6.

Should this remain correct?