Testing with databases can be tricky. If you are developing a system married
to a single database then you can make some assumptions about your environment
and ask the user to provide relevant connection information. But if you need
to test a framework that uses DBI, particularly a framework that uses
different types of persistence schemes, then it may be more useful to simply
verify what the framework is trying to do -- ensure the right SQL is generated
and that the correct parameters are bound. DBD::Mock makes it easy to just
modify your configuration (presumably held outside your code) and just use it
instead of DBD::Foo (like DBD::Pg or DBD::mysql) in your framework.
