Assuming you shipped your module to CPAN with working tests, test failures from
CPAN Testers might be due to platform issues, Perl version issues or problems
with dependencies. This module helps you diagnose deep dependency problems by
showing you exactly what modules and versions were loaded during a test run.

When this module is loaded, it sets up an END block that will take action if the
program is about to exit with a non-zero exit code or if
$test_builder->is_passing is false by the time the END block is reached. If that
happens, this module prints out the names and version numbers of non-local
modules appearing in %INC at the end of the test.

WWW: https://metacpan.org/release/Test-DiagINC