Automatic Testing

Here's what I used
First, I made a record of what the output was supposed to look like:

        perl extract1.pl
        mv OUT.out SAMPLE-OUTPUT

Then I wrote test.pl:

        #!/usr/bin/perl

        my $prog = shift || 'extract3.pl';
        chdir("/home/mjd/TPC/2002/Flags/extract") or die $!;
        system("perl $prog");
        system("cmp -s SAMPLE-OUTPUT OUT.out");
        print $? == 0 ? "ok\n" : "not ok\n";

After each change, run test.pl
If it says not ok, examine OUT.out to see what is wrong
Isn't that simple?