mp has asked for the wisdom of the Perl Monks concerning the following question:

I am writing a self-contained perl script (no reliance on external modules), and I would like to glassbox/whitebox subroutines in it from a separate test script without running the code in package main in the original perl script. What is a good way to go about doing this?

The only thing I have come up with so far is to add some special comments before and after the code that I don't want to execute under test, then make the test script read the script under test into a scalar or array, strip out the code that should not be executed, then eval what is left over to create the package and subroutines/methods, then run the tests against those subroutines. Is there a way of achieving the same effect without jumping through the extra hoops? Is there a way for a perl script to tell if it is being run from a shell versus being 'require'-ed? If it makes a difference, the script will be run on Win32.

To clarify, here is some example code:
In script_under_test: 
#!/usr/local/bin/perl -w
#<ignore_during_test>
my $obj = SupportingPackage->new;
$obj->do_something;
$obj->do_something_else;
#</ignore_during_test>
package SupportingPackage;
sub new { bless {}, $_[0]; }
sub do_something { 1;}
sub do_something_else { 2;}

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In 01test.t: 

use strict; use warnings;
use Test::More tests => 2;
#... pull in package SupportingPackage somehow 
#without running code that is in main ...
# then:
ok(my $obj = SupportingPackage->new);
can_ok($obj, 'do_something');
is($obj->do_something, 1);
can_ok($obj, 'do_something_else');
is($obj->do_something_else, 2);
# etc.

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Replies are listed 'Best First'.
Re: Testing subroutines from a script
by chromatic (Archbishop) on Aug 30, 2002 at 19:32 UTC

    If you're running your tests under Test::Harness, it'll set $ENV{HARNESS_ACTIVE} for you. You can then write: 

    sub main
{
    # everything you'd normally execute here
}

main() unless ($ENV{HARNESS_ACTIVE});

    [download]
[reply]
[d/l]
[select]
      Thank you. This works great. I added 
      BEGIN { $ENV{HARNESS_ACTIVE} = 1 }

      [download]
      to the test script so that it will work regardless of whether it is invoked under Test::Harness.
[reply]
[d/l]
Re: Testing subroutines from a script
by mp (Deacon) on Aug 30, 2002 at 19:22 UTC
    I realize that I could just add a test mode to the script_under_test, but would prefer not to do that.
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