Mine

sub error
{
    for (@_) {
        print $_;
        my @splitline = split(/ *\| */,$_);
        print @splitline;
        pop @splitline; shift @splitline;

        unless (pop @splitline eq 'error') {exit;}

        print 'When ';
        if ($splitline[0] eq 'Y' && print 'target is North, ') {}
        elsif ($splitline[0] eq 'N' && print 'target is South, ') {}
        if ($splitline[1] eq 'Y' && print 'target is East, ') {}
        elsif ($splitline[1] eq 'N' && print 'target is West, ') {}
        my %dirs = (2,'ahead',3,'behind',4,'left',5,'right');
        for (keys %dirs) {
                if ($splitline[$_] ne '-' && print 'wall is ', $dirs{$_}, ',') {}
        }
        print " then the test fails.\n";
    }
}sub error
{
    for (@_) {
        print $_;
        my @splitline = split(/ *\| */,$_);
        print @splitline;
        pop @splitline; shift @splitline;

        unless (pop @splitline eq 'error') {exit;}

        print 'When ';
        if ($splitline[0] eq 'Y' && print 'target is North, ') {}
        elsif ($splitline[0] eq 'N' && print 'target is South, ') {}
        if ($splitline[1] eq 'Y' && print 'target is East, ') {}
        elsif ($splitline[1] eq 'N' && print 'target is West, ') {}
        my %dirs = (2,'ahead',3,'behind',4,'left',5,'right');
        for (keys %dirs) {
                if ($splitline[$_] ne '-' && print 'wall is ', $dirs{$_}, ',') {}
        }
        print " then the test fails.\n";
    }
}