perldoc > ExtUtils::testlib(3perl)

NAME
    ExtUtils::testlib - add blib/* directories to @INC

SYNOPSIS
      use ExtUtils::testlib;

DESCRIPTION
    After an extension has been built and before it is installed it may be desirable to test it
    bypassing "make test". By adding

        use ExtUtils::testlib;

    to a test program the intermediate directories used by "make" are added to @INC.