Regex - starts with a particular string but does not end with another substring

Question

Given two strings s1 and s2, I am trying to write a regex that will match a string that starts with s1 but does not end with s2

Answer 1

Try this:

/^(?!.+BAD$)TEST-.*/

This matches the start, goes ahead and rejects anything ending in the bad string, then matches the desired pattern.

Here's a demo that passes all four of your tests (click "RUN TESTS" at the bottom to verify).