How do you write a unit test for a regex pattern?

Question

Is it possible? Would it require a existing whitewashed and/or blacklisted datasets, or not? How would you know an exception did not exist?

Answer 1

whitelists and blacklists sounds a good approach, I don't think you can "prove" it will work without exception so empirical verification is appropriate and in keeping with the spirit of unit testing

as you think up more complex/edge-case examples to test with, just add them and see if it still works, thus building a test suite in which you have ever greater levels of confidence

also, answered previously very thoroughly here

http://stackoverflow.com/questions/488601/how-do-you-unit-test-regular-expressions

Answer 2

You might want to look at the following link with an identical discussion that has several good solutions:

How do you unit test regular expressions?
http://stackoverflow.com/questions/488601/how-do-you-unit-test-regular-expressions