#!/usr/bin/env perl
use strict;
use warnings;

sub not_only_atgc {
    my $sequence = shift;
    if ( $sequence =~ /[^atgc]/i ) {
        return 1;
    }
    return 0;
}

my %test_criteria = (
    "Must not be 19 characters long" => sub {
       return 1 if (length($_[0]) != 19);
    },
    "Must contain other than atgc" => \&not_only_atgc,
);

my $lineno = 0;

# Read one line at a time
open( my $fh, "data.txt" ) or die "$!";
LINE:
while ( my $line = <$fh> ) {
    $lineno++;
    my @words = split /\s+/, $line;
    print "Processing line $lineno interested in $words[2]\n";

    TEST:
    for my $criteria_check ( keys %test_criteria ) {
        if ( $test_criteria{$criteria_check}->( $words[2] ) ) { # Test returned 1
        } else {
           print "Fail: $criteria_check\n\n";
           next LINE;
        }
    }

    ## All checks have passed after this line ##
    print "$words[2] passes all criteria\n\n";
}