Test data was taken from the Go distribution, which was in turn taken from the testregex test suite: http://www2.research.att.com/~astopen/testregex/testregex.html The LICENSE in this directory corresponds to the LICENSE that the data was released under. The tests themselves were modified for RE2/Go. A couple were modified further by me (Andrew Gallant) (only in repetition.dat) so that RE2/Go would pass them. (Yes, it seems like RE2/Go includes failing test cases.) This may or may not have been a bad idea, but I think being consistent with an established Regex library is worth something. Note that these files are read by 'src/etc/regexp-match-tests' and turned into Rust tests found in 'src/libregexp/tests/matches.rs'.