TypeError: fake_init_exception() with Neutron exceptions in the tests

[Julie Pichon]

When a Neutron Client exception is thrown in the unit tests (usually because a call wasn't mocked properly, see e.g. bug 1284664), the following error is displayed instead of the actual error:

TypeError: fake_init_exception() takes exactly 3 arguments (1 given)

Neutron seems to prefer to declare exceptions by overriding the message attribute (and possibly adding additional information later, like a 'reason' for the failure), rather than passing the code + message around as arguments. We should handle this appropriately and display the correct message.

An example of how to reproduce:
1. Open https://git.openstack.org/cgit/openstack/horizon/tree/openstack_dashboard/dashboards/project/instances/tests.py?id=e0dc562ec8
2. Comment out the api.network key/values from the stub declarations (L56-58), and comment out the network mocks in the test (L72, L75-76)
3. Run the tests

Actual results:
4. Trace shows as TypeError: fake_init_exception() takes exactly 3 arguments (1 given)

Expected results:
4. Trace shows the actual error (here something like Connection to Neutron failed: Maximum attempts reached)

[Openstack Gerrit (openstack-gerrit)]

Fix proposed to branch: master
Review: https://review.openstack.org/91586

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/91586
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=b04d26a51a8a2673b88b5b4da473f37d9a0209b4
Submitter: Jenkins
Branch: master

commit b04d26a51a8a2673b88b5b4da473f37d9a0209b4
Author: Julie Pichon <email address hidden>
Date: Thu May 1 15:41:01 2014 +0100

    Fix fake_init_exception() to better handle Neutron exceptions

    Neutron often declares exceptions by overriding the message attribute
    and possibly adding additional information later, like a 'reason' for
    the failure, rather than passing the code and message around as
    arguments. We should handle this appropriately and display the correct
    message, instead of failing with "TypeError: fake_init_exception()
    takes exactly 3 arguments (1 given)"

    Change-Id: Ib838704cb9ca968ddfc6e3bfed3af7d0ea08f384
    Closes-Bug: #1315035