Yup, you read that right. I needs something that is capable of generating random text from a regular expression. So the text should be random, but be matched by the regular expression. It seems it doesn't exist, but I could be wrong.
Just a an example: that library would be capable of taking '[ab]*c' as input, and generate samples such as:
abc
abbbc
bac
etc.
Update: I created something myself: Xeger. Check out http://code.google.com/p/xeger/.
I just created a library for doing this a minute ago. It's hosted here: http://code.google.com/p/xeger/. Carefully read the instructions before using it. (Especially the one referring to downloading another required library.) ;-)
This is the way you use it:
String regex = "[ab]{4,6}c";
Xeger generator = new Xeger(regex);
String result = generator.generate();
assert result.matches(regex);