data structures checking elements of elements changing in ignoring specific values in order of elements unknown for showing differences between 2nd testing equality of databases as backend for web site, testing data in, testing mocking temporary test databases cleaning up data after test deleting after test shipping DBD::AnyData driver DBD::Mock module DBD::SQLite driver DBI module 2nd Devel::Cover module die() function, Test::More module directory hierarchy for modules distribution signatures distributions, testing documentation coverage