As I wrote two weeks ago, I consider the QA related changes in Ubuntu 12.04 a great success. But while we will continue and even extend our efforts there, this is not where the ball stops: it’s great to have the feedback cycle between “break it” and “notice the bug” reduced from potentially a few months to one day in many cases, but wouldn’t it be cool to reduce that to a few minutes, and also put the machinery right at where stuff really happens — into the upstream trunks? If for every commit to PyGObject, GTK, NetworkManager, udisks, D-BUS, telepathy, gvfs, etc. we’d immediately build and test all reverse dependencies and the committer would be told about regressions?

I have had the desire to work on automated tests in Linux Plumbing and GNOME for quite a while now. Also, after 8 years of doing distribution work of packaging and processes (tech lead, release engineering/management, stable release updates, etc.) I wanted to shift my focus towards technology development. So I’ve been looking for a new role for some time now.

It seems that time is finally there: At the recent UDS, Mark announced that we will extend our QA efforts to upstream. I am very happy that in two weeks I can now move into a role to make this happen: Developing technology to make testing easier, work with our key upstreams to set up test suites and reporting, and I also can do some general development in areas that are near and dear to my heart, like udev/systemd, udisks, pygobject, etc. This work will be following the upstream conventions for infrastructure and development policies. In particular, it is not bound by Canonical copyright license agreements.

I have a bunch of random ideas what to work on, such as:

  • Making it possible/easier to write tests with fake hardware. E. g. in the upower integration tests that I wrote a while ago there is some code to create a fake sysfs tree which should really go into udev itself, available from C and introspection and be greatly extended. Also, it’s currently not possible to simulate a uevent that way, that’s something I’d like to add. Right now you can only set up /sys, start your daemon, and check the state after the coldplugging phase.
  • Interview some GNOME developers what kind of bugs/regressions/code they have most trouble with and what/how they would like to test. Then write a test suite with a few working and one non-working case (bugzilla should help with finding these), discuss the structure with the maintainer again, find some ways to make the tests radically simpler by adding/enhancing the API available from gudev/glib/gtk, etc. E. g. in the tests for apport-gtk I noticed that while it’s possible to do automatic testing of GUI applications it is still way harder than it should and needs to be. I guess that’s the main reason why there are hardly any GUI tests in GNOME?
  • I’ve heard from several people that it would be nice to be able to generate some mock wifi/ethernet/modem adapters to be able to automatically test NetworkManager and the like. As network devices are handled specially in Linux, not in the usual /dev and sysfs manner, they are not easy to fake. It probably needs a kernel module similar to scsi_debug, which fakes enough of the properties and behaviour of particular nmetwork card devices to be useful for testing. One could certainly provide a pipe or a regular bridge device at the other end to actually talk to the application through the fake device. (NB this is just an idea, I haven’t looked into details at all yet).
  • For some GUI tests it would be much easier if there was a very simple way of providing mocks/stubs for D-BUS services like udisks or NetworkManager than having to set up the actual daemons, coerce them into some corner-case behaviour, and needing root privileges for the test due to that. There seems to be some prior art in Ruby, but I’d really like to see this in D-BUS itself (perhaps a new library there?), and/or having this in GDBus where it would even be useful for Python or JavaScript tests through gobject-introspection.
  • There are nice tools like the Clang static code analyzer out there. I’d like to play with those and see how we can use it without generating a lot of false positives.
  • Robustify jhbuild to be able to keep up with building everything largely unattended. Right now you need to blow away and rebuild your tree way too often, due to brittle autotools or undeclared dependencies, and if we want to run this automatically in Jenkins it needs to be able to recover by itself. It should be able to keep up with the daily development, automatically starting build/test jobs for all reverse dependencies for a module that just has changed (and for basic libraries like GLib or GTK that’s going to be a lot), and perhaps send out mail notifications when a commit breaks something else. This also needs some discussion first, about how/where to do the notifications, etc.

Other ideas will emerge, and I hope lots of you have their own ideas what we can do. So please talk to me! We’ll also look for a second person to work in that area, so that we have some capacity and also the possibility to bounce ideas and code reviews between each other.

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