Public bug reported:
autopkgtest is "clever" about when it resets the testbed betweens tests,
and this is a Bad Thing (tm) when it breaks assumptions about isolation.
Specifically, in lib/adt_testbed.py under Testbed.reset is found the
following code:
def reset(self, deps_new, with_recommends):
'''Reset the testbed, if possible and necessary'''
adtlog.debug('testbed reset: modified=%s, deps_installed=%s(r: %s),
deps_new=%s(r: %s)' %
(self.modified, self.deps_installed,
self.recommends_installed,
deps_new, with_recommends))
if 'revert' in self.caps and (
self.modified or self.recommends_installed != with_recommends or
[d for d in self.deps_installed if d not in deps_new]):
adtlog.debug('testbed reset')
pl = self.command('revert', (), 1)
self._opened(pl)
self.modified = False
Paraphrasing, if the test-bed is capable of reversion ('revert' in
self.caps), and the current test's dependencies (self.deps_installed)
include packages that are *not* present in the next test's dependencies
(deps_new), or if the recommends list has changed, then *and only then*
is the test bed sent the "revert" command which will reset it completely
(in the case of virt-qemu this restarts the VM from scratch). Otherwise
it doesn't bother.
If one makes the (fairly reasonable?) assumption that tests operate in
isolation to one another this can lead to some ... surprising results.
Consider the following d/t/control:
Test-Command: touch /etc/foo
Depends: build-essential
Restrictions: isolation-machine, needs-root
Test-Command: test -e /etc/foo
Depends: build-essential
Restrictions: isolation-machine, needs-root
If the tests are truly isolated, this *should* fail ... but it doesn't.
Reverse the order of the tests, and of course it does fail. Or add
another package to the Depends of the first test (so it's a superset of
the second test) and it fails.
Having spent quite some time failing to debug something, because I'd
made the faulty assumption that tests were actually isolated, this level
of "clever" is annoying and should either be removed or at least
documented, preferably in the man-page so it jumps out at me next time
I've forgotten this!
** Affects: autopkgtest (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2058040
Title:
autopkgtest doesn't isolate testbeds (sometimes!)
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