Unit tests should not use assert statements

[Vitalii Lebedynskyi]

Some unit tests make assertion using assert statements. That should be refactored to using appropriate assert methods.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/85560

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/85560
Committed: https://git.openstack.org/cgit/openstack/ceilometer/commit/?id=89850c27ae714563bf13470b886e8c7d9b7a101f
Submitter: Jenkins
Branch: master

commit 89850c27ae714563bf13470b886e8c7d9b7a101f
Author: Vitalii Lebedynskyi <email address hidden>
Date: Sat Apr 5 21:18:54 2014 +0300

    Replace assert statements with assert methods

    Some of the test methods were using python assert
    statements for making assertions. This patch replaces
    those statements with apropriate assert methods.

    Change-Id: I3fcf4253560474868a0b32a7994f446e7b4bcc67
    Closes-bug: #1303124