You have three major problems.

• Perl comes with a module called test. You aren't loading the module you think you are loading until you added use lib '.';, which causes your module to be found before the one that comes with Perl.

• use test (); means import nothing

  use test; means import everything the module exports by default. With module using Exporter, that would be the items listed in @EXPORT. In the case of your module, that means import nothing.

• Modules loaded using require (including those loaded using use) must have a package statement for them to work correctly when loaded from two different namespaces (such as from the main script and from a module).

  You'll notice by adding the package statement that your module will need to use Exporter (or similar) to export testroutine to the caller.

#!/usr/bin/perl

use warnings;
use strict;

#use MyTest;                  # Imports what's in the module's @EXPORT
#use MyTest ( );              # Won't work.
#use MyTest qw( );            # Another way of writing the same thing.
use MyTest qw( testroutine ); # Imports testroutine and nothing else.

my $output = testroutine();
print $output, "\n";
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# MyTest.pm

use strict;
use warnings;

package MyTest;

BEGIN {
   our @EXPORT    = qw( );              # Export nothing by default.
   our @EXPORT_OK = qw( testroutine );
   require Exporter;
   *import = \&Exporter::import;
}

# Put other "use" statements here, if any.

sub testroutine {
   return "This is a test";
}

1;
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