Testing if "This::Package" is available (installed):

$ perl -MThis::Package -e 1

For example:

$ perl -MB::Deparse -e 1
$ perl -MThis::Package -e 1
Can't locate This/Package.pm in @INC (you may need to install the This
+::Package module) (@INC contains: /home/netbook/tmp/perl-5.24/lib/sit
+e_perl/5.24.1/i686-linux-thread-multi /home/netbook/tmp/perl-5.24/lib
+/site_perl/5.24.1 /home/netbook/tmp/perl-5.24/lib/5.24.1/i686-linux-t
+hread-multi /home/netbook/tmp/perl-5.24/lib/5.24.1 .).
BEGIN failed--compilation aborted.
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Note: if installed, no output is shown.

Have fun!