while (<TEST>) {
  my ($key,@fileData) = split /\|/;
  chomp @fileData;
  $test{$key} = \@fileData;
}
#to
while (<TEST>) {
  chomp;
  my ($key,@fileData) = split /\|/;
  $test{$key} = \@fileData;
}

##</code><code>##

foreach my $key (keys %test) {
      push (@sorted, "$key|$test{$key}->[0]|$test{$key}->[1]|$test{$key}->[2]|$test{$key}->[3]");
}
#to 
foreach my $key (keys %test) {
  	push @sorted, (join '|', ($key,@{$test{$key}});        
}

##</code><code>##

open(TEST, ">test.txt") || die "File couldn't be opened for writing: $!";
foreach my $key (sort keys %test) {
  print TEST (join '|', ($key,@{$test{$key}});
  print TEST "\n";
} 
close(TEST);

##</code><code>##

foreach my $key (sort keys %test) {
#to
foreach my $key (sort { $test{$a}[-1] <=> $test{$b}[-1] } keys %test) {