Pool setup/destroy may be a time consuming operation, allow them to be
asynchronous. Fortunately add_pool and remove_pool are used only through
Admin API, so the change does not require modification of other
components.
If QUBES_TEST_TEMPLATES or QUBES_TEST_LOAD_ALL is set, create testcases
on modules import, instead of waiting until `load_tests` is called.
The `QUBES_TEST_TEMPLATES` doesn't require `qubes.xml` access, so it
should be safe to do regardless of the environment. The
`QUBES_TEST_LOAD_ALL` force loading tests (and reading `qubes.xml`)
regardless.
This is useful for test runners not supporting load_tests protocol. Or
with limited support - for example both default `unittest` runner and
`nose2` can either use load_tests protocol _or_ select individual tests.
Setting any of those variable allow to run a single test with those
runners.
With this feature used together load_tests protocol, tests could be
registered twice. Avoid this by not listing already defined test classes
in create_testcases_for_templates (according to load_tests protocol,
those should already be registered).
Besides converting itself, change how the test verify restore
correctness: first collect VM metadata (and hashes of data) into plain
dict, then compare against it. This allow to destroy old VMs objects
before restoring the backup, so avoid having duplicate objects of the
same VM - which results in weird effects like trying to undefine libvirt
object twice.
Changed the inheritance hierarchy:
1. Renamed `SystemTestsMixin` to `SystemTestCase`
2. `SystemTestCase` is a child of `QubesTestCase`
3. All classes extending the prior `SystemTestsMixin` now just extend `object`
