you can solve this two ways.

1. do "test_func.pm"; instead of use test_func;

2. change test_func.pm to a proper package that exports its functions:

package test_func;
use base qw(Exporter);
our @EXPORT = qw(test_me);

sub test_me {
    my $txt = shift;
    print "Exec of test_me with: $txt\n";
    return $txt;
}

1;
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