faker

Faker::Base.regexify

Given a regular expression, attempt to generate a string
that would match it.  This is a rather simple implementation,
so don't be shocked if it blows up on you in a spectacular fashion.

It does not handle ., *, unbounded ranges such as {1,},
extensions such as (?=), character classes, some abbreviations
for character classes, and nested parentheses.

I told you it was simple. :) It's also probably dog-slow,
so you shouldn't use it.

It will take a regex like this:

/^[A-PR-UWYZ0-9][A-HK-Y0-9][AEHMNPRTVXY0-9]?[ABEHMNPRVWXY0-9]? {1,2}[0-9][ABD-HJLN-UW-Z]{2}$/

and generate a string like this:

"U3V  3TP"

Source | Google | Stack overflow