They all seemed to complain about the same thing:

Can't locate object method "new" via package "Test::Compile" at t/00-compile.t line 6.
t/00-compile.t ......
Dubious, test returned 255 (wstat 65280, 0xff00)
No subtests run

That was strange, but I recalled a similar report earlier by Henk van Oers. Back then we did not do anything with it, he has just upgraded Test::Compile to the latest release and that fixed the issue for him. I have not asled him how he even got to the situation where his version of Test::Compile was older than what I put as requirement into Makefile.PL that looked like this:

'Test::Compile'  => 1.2.1,

I figured, maybe he has not run perl Makefile.PL or for some reason disregarded when Makefile.PL ask him to upgrade the module. That happens when we do things manually, but that does not require any fixing in Pod::Tree.

However this time the automated smoke-test gave similar error messages so I went to the test report again and looked at the "PREREQUISITES" section that looked like this:

------------------------------
PREREQUISITES
------------------------------

Prerequisite modules loaded:

requires:

    Module              Need  Have    
    ------------------- ----- --------
    File::Find          1     1.23    
    HTML::Stream        1.49  1.60    
    IO::File            1     1.16    
    IO::String          1     1.08    
    Path::Tiny          0.068 0.068   
    Pod::Escapes        1.02  1.04    
    Test::Compile       0     0.24    
    Test::More          1     1.001002
    Text::Template      1     1.46    

build_requires:

    Module              Need  Have    
    ------------------- ----- --------
    ExtUtils::MakeMaker 0     6.84    

configure_requires:

    Module              Need  Have    
    ------------------- ----- --------
    ExtUtils::MakeMaker 0     6.84    

Specifically the "Need" column.

For every other module Makefile.PL has correctly set the "Need" to the number we have in Makefile.PL except for Test::Compare.

Obviously if the requirement is to have version 0 and a machine already has version 0.24 then it won't be upgraded and then we'll get the error Henk received and the CPAN Tester received. The question then

Why does Makefile.PL think 1.2.1 is 0 ?

I asked it on the CPAN Testers discussion list and I got a few responses in this thread.

I got several answers, one of them from Alexandr Ciornii, the owner of that smoke-machine. It's nice to get a quick response from people who are so involved.

Normally 1.2.1 should be seen as a so-called v-string, but old versions of ExtUtils::MakeMaker don't recognize it and assume 0.

The recommended solutions were either to add quotes around the thing (I can't really call it a number, can I?) and write

'Test::Compile'  => '1.2.1',

or it could be written in decimal form:

'Test::Compile'  => 1.002001,

A third alternative would be to just use one decimal point and disregard the extra digit, though this is not exactly the same requirement.

'Test::Compile'  => 1.2,

At the same time I also received a pull request from Alexandr Ciornii using the quotes around the version number. He even sneaked in a change adding use 5.006 to Makefile.PL

I have accepted the pull request and merged it.

Do not declare test prereqs as runtime prereqs

In addition to the above pull-request, I've also received a new issue.

The thing is that I've added several modules to the PREREQ_PM of the Makefile.PL that we only need for testings. For example Test::More and Test::Compile that we just had issues with. This means people who install the module will also need to install those modules and not just in a temporary directory. This means that downstream distributors (e.g. Linux distributions, and BSDs) that want to re-distribute the Pod-Tree distribution will have to set all these modules as runtime prerequisites.

I don't think it is a big issue, disk space is very cheap, but I think it is better to state the requirements properly.

So I changed the Makefile.PL a bit. Created a main %config that will be later passed to the WriteMakefile function. Moved the list of test-modules to a separate hash and added them back to the %config based on the version number of ExtUtils::MakeMaker.

my %config = (
    NAME         => 'Pod::Tree',
    VERSION_FROM => 'lib/Pod/Tree.pm',    # finds $VERSION
    DISTNAME     => 'Pod-Tree',
    ...
    PREREQ_PM => {
        'File::Find'     => 1,
        'HTML::Stream'   => 1.49,
        'IO::File'       => 1,
        'IO::String'     => 1,
        'Pod::Escapes'   => 1.02,
        'Text::Template' => 1,
    },
    ...
);
my %test_requires = (
    'Test::More'    => 1,
    'Test::Compile' => '1.2.1',
    'Path::Tiny'    => 0.068,
);

if ( eval { ExtUtils::MakeMaker->VERSION(6.64) } ) {
    $config{TEST_REQUIRES} = \%test_requires;
}
else {
    $config{BUILD_REQUIRES} = \%test_requires;
}

WriteMakefile(%config);

commit

I hope this will work correctly.