I think that specifically binding types to parameters/variables - and accepting them in the calls - kinda promises the end-user that the types will be honored. In this case, the bug isn't really in DBD::CSV, but in DBD::File, and I have meanwhile commited a patch that applies basic types in these cases when they are requested.

Unless speified in one way or another, DBD::CSV would of course not be able to set those types itself when reading/analyzing files.

I'm now done with the conversion to Test::More, and found out that this process at least fixed one RT bug along the way.

Devel::Cover by the way is a great tool to craft TODO lists :).

Update: More important, related to the original post, it was tested for, so even the original author was expecting it to work, but the tests didn't test what it was supposed to test, and thus hiding the bug. Documented or not, this is very very unwanted behaviour.