Re^2: Testing legacy CGI scripts using the "main() unless caller()" technique

Here's the script being tested:

#!/opt/perl524

use strict;
use warnings;

main()
    unless caller();

sub main {
    use CGI;
    my $cgi = CGI->new;

    if ( !$cgi->param ) {
        print $cgi->header, my_form( 'action_url' => $cgi->url() );
        exit;
    }

    my $num1 = $cgi->param('num1') || '';
    my $num2 = $cgi->param('num2') || '';

# Next, add the value of the incoming parameters and display a result 
+(not shown here)
#
    my $sum = add_two_numbers( $num1, $num2 );

# Then print a result to the web browser and display a fresh form unde
+r the result (not shown here)

    exit;
} ## end sub main

sub add_two_numbers {
    my ( $num1, $num2 ) = @_;
    return $num1 + $num2;
}

sub my_form {
    my %params     = @_;
    my $action_url = $params{'action_url'} || '';
    die
        "No URL specified for the 'action' attribute of the form, can'
+t continue"
        if ( !$action_url );

    my $form = qq|<html>
<head>
<title>Add Two Numbers</title>
</head>
<body>
<h1>Add Two Numbers</h1>
<form action="$action_url" method="post">
<p>Enter some first number: <input name="num1"></p>
<p>Enter some second number: <input name="num2"></p>
<p><input type="submit" value="Add Now"></p>
</form>
|;
} ## end sub my_form
[download]

Here's the test script:

#!/opt/perl524

use strict;
use warnings;

use Test::More ('no_plan');

my $SCRIPT_LOCAL_LOCATION
    = 'C:\Users\davel\Documents\scripts\add_two_numbers_modified_as_ma
+in.cgi';

require_ok($SCRIPT_LOCAL_LOCATION)
    or exit;

ok( add_two_numbers( 3, 17 ) == 20, "3 plus 17 produces 20" );

done_testing();
[download]

Here are the results of running the test script:

ok 1 - require 'C:\Users\davel\Documents\scripts\add_two_numbers_modif
+ied_as_main.cgi';
ok 2 - 3 plus 17 produces 20
1..2
[download]

But when I change the first line of the script being tested, so as to be the following:

#!/opt/perl524

use strict;
use warnings;

main() if ( !caller() );

sub main {
    use CGI;
    my $cgi = CGI->new;

    if ( !$cgi->param ) {
        print $cgi->header, my_form( 'action_url' => $cgi->url() );
        exit;
    }

    my $num1 = $cgi->param('num1') || '';
    my $num2 = $cgi->param('num2') || '';

# Next, add the value of the incoming parameters and display a result 
+(not shown here)
#
    my $sum = add_two_numbers( $num1, $num2 );

# Then print a result to the web browser and display a fresh form unde
+r the result (not shown here)

    exit;
} ## end sub main

sub add_two_numbers {
    my ( $num1, $num2 ) = @_;
    return $num1 + $num2;
}

sub my_form {
    my %params     = @_;
    my $action_url = $params{'action_url'} || '';
    die
        "No URL specified for the 'action' attribute of the form, can'
+t continue"
        if ( !$action_url );

    my $form = qq|<html>
<head>
<title>Add Two Numbers</title>
</head>
<body>
<h1>Add Two Numbers</h1>
<form action="$action_url" method="post">
<p>Enter some first number: <input name="num1"></p>
<p>Enter some second number: <input name="num2"></p>
<p><input type="submit" value="Add Now"></p>
</form>
|;
} ## end sub my_form
[download]

Then when I run the identical test script, I get:

not ok 1 - require 'C:\Users\davel\Documents\scripts\add_two_numbers_m
+odified_as_main.cgi';
#   Failed test 'require 'C:\Users\davel\Documents\scripts\add_two_num
+bers_modified_as_main.cgi';'
#   at C:\Users\davel\Documents\scripts\add_two_numbers_modified_as_ma
+in.cgi.t line 11.
#     Tried to require ''C:\Users\davel\Documents\scripts\add_two_numb
+ers_modified_as_main.cgi''.
#     Error:  C:\Users\davel\Documents\scripts\add_two_numbers_modifie
+d_as_main.cgi did not return a true value at (eval 8) line 2.
1..1
# Looks like you failed 1 test of 1.
[download]

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