Is it possible to install perl prerequisites before distribution testing and how?

Question

I try to build a Perl distribution for a home-made module, from the Module::Starter base. Every test pass on my machine, but when I upload it to CPAN to get some more universal tests from cpantesters.org, some test failed on other architectures or OS, but I can't understand why. I can see in test reports that some of my prerequisites are not installed before testing but I would like it to.

I've tried to list these dependencies into the Makefile.PL PREREQ_PM hash and then in the TEST_REQUIRES hash, but it didn't changed a lot of results.

Then, when I've removed the dependencies from my local machine and tried to install my module using Cpanm, it downloads dependencies first, test passed and install has been a success.

This is my first try for a module, so I think I am missing something, maybe I am too used of the Cpanm magic. Thanks for any help.

Answer 1

The problem is something different. Andreas' smoker very probably built the dependency App::Ack (which looks in the fail reports like being absent) successfully. But here come at least two problems:

• When a distribution gets tested, then its dependencies may or may not be installed already. However, it's guaranteed that all dependent modules are made available through the PERL5LIB environment variable, so make test usually works (To be more specific, if the install Module command is used in the CPAN shell, then all dependencies are installed immediately. If the test Module command is used, then dependencies are only built, but not installed. The CPAN user can do the installation later using install_tested). So it may be that App::Ack is not installed here, just built. Especially this means that the ack script is not installed in the final location.
• Even if it is installed, many smoke testers or users who have multiple perls installed in parallel use a non-standard directory for this perl. So ack wouldn't be installed in /usr/bin or /usr/local/bin, but in the bin directory belonging to this perl. This directory may or may not be in the user's PATH at all. So you cannot assume that can_run("ack") works here. A workaround here is to add $Config{scriptdir} temporarily to $ENV{PATH}. Another solution would be to use the App module instead of the script, if it's possible. Unfortunately it looks like ack can only be called as a script.

If you look at a sample fail report, then you can see that App::Ack was installed (it appears in the PREREQUISITES section both under requires and build_requires, you can also see which App::Ack version is installed in the "HAVE" column). You can also see the user's PATH (in the ENVIRONMENT section). And you may guess about the scriptdir for this perl, it's usually the same directory where the perl binary itself is installed, and the path to current perl is visible in $^X (under "Perl special variables").

If you want to reproduce the behavior, then you need to deinstall ack from your machine, build a custom perl using ./configure.gnu --prefix=/path/to/custom/perl-5.X.Y, and use this perl for tests.