The Perl/CPAN community places a lot of emphasis on testing. Testing early, testing often, and testing thoroughly.
But unfortunately, sometimes we go a bit over the top.
Yes, it is extremely important that the tests are written and run by the author.
Yes, it is very important that the tests are run by a collection of people other than the author, especially on other platforms and locales. This catches lots of common errors, such as file path names in tests, forgetting to specify dependencies in the Makefile.PL, locale assumptions, and so on.
HOWEVER, in the context of an end-user installation, things are different and it is actually less important that the tests are actually run.
Test failures in both the author and CPAN Testers contexts are iterative events. The author is getting feedback and using that feedback to improve the codebase. And nothing matters except for the information such failures provide to the author.
However, when an end-user is installing a module, test failures mean installation failure for the end-user. There are no steps they can reasonably and safely take to resolve the problem immediately.
So it is important to consider whether you REALLY want to any specific subset of tests to run or not.
Because by running a test, you are effectively saying that you would rather the end user not use a module at all, rather than continue.
For core tests of functionality, this is obviously the case. If it's breaking, you DON'T want them using it.
But for things like POD tests or coverage of Perl::Critic, or optional features, or expanded tests, and so on and so forth, this is not always going to be the case.
As a module author, you can often make a fairly reasonable judgment call that if the core tests and platform tests all pass, and the optional feature testing works for both the author of the package and for CPAN Testers folks, the nature of that optional feature is such that it is highly unlikely to break for end users.
And so it's perfectly fine to skip those tests and have them not run.
The same thing is the case for PREREQs (module dependencies).
By listing something as a dependency, you are saying you would rather not have the end user install your module AT ALL, if that module is not available.
I mention this mostly because of this journal entry.
The author in this case is so concerned about not running tests, that he has contorted the dependencies in a circular.
This really shouldn't be a problem.
You just avoid running those optional tests for the end-user, or consider moving them into the optional package.
Because that optional module isn't a dependency if it depends on the original package. It's a plug-in type of package.
The feature used should probably be removed altogether from the main package, so that anything needing the additional feature should have to install the plug-in separately, and module authors should have a separate dependency for it.
And if an interactive question and answer "which features do you want" type thing is REALLY needed, than we can follow the example of Task::Catalyst, and wrap an interactive Task module over the top of the lot.