Overview

Parallel testing would be nice. Theres a bunch of things to do to make it work. See the LEP for constraints/goals/resourcing.

Known bugs/issues: parallel test bugs

LXC containers and parallel testing

LXC containers combined with aufs offer a pretty cheap way to get solid isolation - a great big hammer of a workaround for our existing globals (shared work dirs etc). William put together a proof of concept, Robert made that generic, and it is now available in lxc for Oneiric and later (as "lxc-start-ephemeral"). That, combined with an updated .testr.conf given in the instructions below (a TODO is to offer profiles for testr) will let testr run tests in a temporary container. (e.g. testr -- -t stories/gpg will fire up an aufs container and run the stories/gpg tests inside it).

Be sure to export LP_LXC_BASE with the name of your lxc base container.

See Running/LXC for info on setting up a base container.

Caveats

• If the base container is running it will be a disaster. Don't try.

• aufs does not seem to permit deletes in some circumstances 729338, so test fixtures which start by deleting a directory tree will fail if the directory tree exists. Known cases:

  • /var/tmp/testkeyserver.test
  • /var/lib/postgresql/8.4/main/postmaster.pid
  • /var/tmp/bazaar.launchpad.dev/mirrors
• and conversely some need a tree:

    File "/home/robertc/source/launchpad/lp-branches/working/lib/canonical/testing/layers.py", line 1775, in startSMTPServer
      handler = logging.FileHandler(log_file)
    File "/usr/lib/python2.6/logging/__init__.py", line 819, in __init__
      StreamHandler.__init__(self, self._open())
    File "/usr/lib/python2.6/logging/__init__.py", line 838, in _open
      stream = open(self.baseFilename, self.mode)
  IOError: [Errno 2] No such file or directory: '/var/tmp/mailman/logs/smtpd'

  - this was because buildmailman had not been run in the base container.

• If we leak a child process with a shared stdout/stderr sshd will not terminate, which will cause the testr test runner to look like it has hung. 820726. sudo pkill memcached can be used to work around this.

Workflow

One-time

• Set up an lxc instance.

• sudo apt-get install testrepository in your host instance.

• In your source tree, run testr init.

• Change your source tree's .testr.conf to the following:

  [DEFAULT]
  test_command=lxc-start-ephemeral -o $LP_LXC_BASE -b $PWD -- xvfb-run $PWD/bin/test --subunit $IDOPTION $LISTOPT
  test_id_option=--load-list $IDFILE
  test_list_option=--list

• You need a temp directory in your source tree to workaround bug 808557

  mkdir temp

Working

• Edit outside the container in your normal work area
• Start the base container to do maintenance: make schema, bin/buildout

  lxc-start -n $basename -d

  • ssh to it
  • make schema
  • bin/buildout

  • shut it down. In theory, sudo poweroff in your container should be sufficient. Experience shows that sometimes this hangs. Therefore, follow the poweroff with lxc-stop -n <name>.

    • Note that, also because of fragility, you may need to manually shutdown postgresql before stopping lxc, to get it to shutdown cleanly.
    • We may investigate creating a second test-only base instance in order to make this easier.

Running tests

• Run tests with testr. These commands assume that your lxc base instance (as created in the initial steps) is named lpdev. If it is named something else, replace "lpdev" with that other name. This also assumes that the base instance is shut down, as described in the previous section. All tests

  LP_LXC_BASE=lpdev TEMP=$(pwd)/temp testr run --parallel

  Some tests

  LP_LXC_BASE=lpdev TEMP=$(pwd)/temp testr run --parallel -- -t stories/gpg