What might be useful is if you passed information via connect() to tell DBD::Mock what type of database handle it should emulate, like:
my $dbh = DBI->connect( 'DBI:Mock:mysql', ... ); my $dbh = DBI->connect( 'DBI:Mock:Pg', ... );
It probably wouldn't be hard to collect a list of valid attributes for each driver and store/return only these, throwing an exception on all others. That's something anyone can do, not just the driver author...
But it's all in stvn's hands now :-)