It might not be obvious but my tinderbox is testing the “unstable” ~x86 keyword of Gentoo. This choice was originally due to the kind of testing (the latest and greatest version of packages for which we don’t know the averse effects of), and I think it has helped tremendously, up to now, to catch things that could have otherwise bit people months, if not years later, especially for the least-used packages. Unfortunately that decision also meant ignoring for the most part the other, now more common architecture (amd64 — although I wonder if the new, experimental amd32 architecture would take its place), as well as ignoring the stable branch of Gentoo, which is luckily tracked by other people from time to time.
Lacking continuous testing though, what is actually considered stable, sometimes it’s not very much so. This problem is further increased by the fact that sometimes the stable requests aren’t proper by themselves: it can be an user asking to stable a package, and the arch teams being called before they should have, it might be an overseen issue that the maintainer didn’t think of, or it might simply be that multiple maintainers had different feelings about stabilisation, which happens pretty often in team-maintained packages.
Whatever the case, once a stable request has been filed, it is quite rare that issues are brought up that are severe enough the stable is denied: it might be that the current stable is in a much worse shape, or maybe it’s a security stable request, or a required dependency of something following one of those destinies. I find this a bit unfortunate, I’m always happy when issues are brought up that delay a stable, even if that sometimes means having to skip a whole generation of a package, just as long as they mean having a nicer stable package.
Testing a package is obviously a pretty taxing task: we have numbers of combination of USE flags, compiler and linker flags, features, and so on so forth. For some packages, such as PHP, testing every and each combination of USE flags is not only infeasible, but just impossible within this universe’s time. to make the work of the arch team developers more bearable, years ago, starting with the AMD64 team, the concept of Arch Testers was invented: so-called “power users” whose task is to test the package and give green light for stable-marking.
At first, all of the ATs were as technically capable as a full-fledged developer, to the point that most of the original ones (me included) “graduated” to full devship. With time this requirement seems to have relaxed, probably because AMD64 became usable to the average user, and no longer just to those with enough knowledge to workaround the landmines originally present when trying to use a 64-bit system as a desktop — I still remember seeing Firefox fail to build because of integer and pointer variable swaps, once that became an error-worthy mistake in GCC 3.4. Unfortunately this also meant that a number of non-apparent issues became even less apparent.
Most of these issues often end up being caused by one simple fault: lack of direction in testing. For most packages, and that includes, unfortunately, a lot of my packages, the ebuild’s selftests are nowhere near comprehensive enough to tell whether the package works or not, and unless the tester actually uses the package, there is little chance that he knows really how to test it. Sure that covers most of the common desktop packages and a huge number of server packages, but that’s far from the perfect solution since it’s the less-common packages that require more eyes on the issues.
What the problem is, with most other software, is that it might require specific hardware, software or configuration to actually be tested. And most of the time, it requires a few procedures to be applied to ensure that it is actually tested properly. At the same time, I only know of Java and Emacs team publishing proper testing procedures for at least a subset of their packages. Most packages could use such a documentation, but it’s not something that maintainers, me included, are used to work on. I think that one of the most important tasks here, is to remind developers when asking stable to come up with a testing plan. Maybe after asking a few times, we’ll get to work and write up that documentation, once and for all.