Perl Unit Testing -- is the subroutine testable?

I have been reading up and exploring on the concept of unit testing and test driven development in Perl. I'm looking into how I can incorporate the testing concepts into my development. Say I have a Perl subroutine here:

sub perforce_filelist {

    my ($date) = @_;

    my $path = "//depot/project/design/...module.sv";
    my $p4cmd = "p4 files -e $path\@$date,\@now";

    my @filelist = `$p4cmd`; 

    if (@filelist) {
        chomp @filelist;
        return @filelist;
    }
    else {
        print "No new files!"
        exit 1;
    }
}

The subroutine executes a Perforce command and stores the output of that command (which is a list of files) in to the @filelist array. Is this subroutine testable? Would testing if the returned @filelist is empty useful? I am trying to teach myself how to think like a unit test developer.