module for adding test failures if warnings are caught

 Test::FailWarnings hooks $SIG{__WARN__} and converts warnings to Test::More's
 fail() calls. It is designed to be used with done_testing, when you don't
 need to know the test count in advance.
 .
 Just as with Test::NoWarnings, this does not catch warnings if other things
 localize $SIG{__WARN__}, as this is designed to catch unhandled warnings.