Potential AttributeError in _get_servers if FlavorNotFound

[Matt Riedemann]

In the Nova servers API (v2 and v3), this line could fail with an AtributeError if there is a FlavorNotFound exception above it:

https://github.com/openstack/nova/blob/2014.1.b3/nova/api/openstack/compute/servers.py#L611

That code should either check if instance_list is empty first or set instance_list to an empty InstanceList object if FlavorNotFound is hit.

[Matt Riedemann (mriedem)]

Introduced in Havana:

https://github.com/openstack/nova/commit/2a781f48c220353b82b748796998b2f5a12c4ad4

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/82607

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/82607
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=32d948124adeb4615ba141164a1c191eed11598d
Submitter: Jenkins
Branch: master

commit 32d948124adeb4615ba141164a1c191eed11598d
Author: Matt Riedemann <email address hidden>
Date: Mon Mar 24 14:12:49 2014 -0700

    Don't attempt to fill faults for instance_list if FlavorNotFound

    When getting a list of servers with details, if a FlavorNotFound is
    raised from the compute API the local instance_list variable is set to
    an empty list, but later instance_list.fill_faults() is called on it
    assuming it is an InstanceList object, which will cause an
    AttributeError.

    This patch just checks to see if instance_list is empty before calling
    fill_faults since InstanceList.fill_faults assumes the list is not empty
    when called, so it's not trivial to simply create an empty InstanceList
    here and set it to the instance_list variable.

    The new test cases use testtools.matchers.HasLength and while seeing
    if testtools was imported I noticed it (along with mox) was in the
    wrong import group, so also fixed the order there.

    This patch also fixes the test_get_server_details_empty unit test to
    actually call the detail method rather than index.

    Closes-Bug: #1296940

    Change-Id: I9f85c2a0b70f41e5bba2da05a2339caf2a8efc3e