https://metacpan.org/pod/CPANPLUS::Config#allow_build_interactivity

Automated smoke testers should set $ENV{AUTOMATED_TESTING} to a true value. This allows authors to skip certain tests (or include certain tests) when the results are not being monitored by a human being.

https://metacpan.org/pod/ExtUtils::MakeMaker#PERL_MM_USE_DEFAULT