Utilizes assertIn and assertNotIn

Using assertTrue and the 'in' operator to test if an element is in a sequence
is too python2.4. Our unit testing framework 'testtools' support assertIn and
assertNotIn, included from python 2.7, which were created for these types of
tests. Let's use assertIn or assertNotIn for these tests.

Change-Id: I8b43f7ff5f306e1ce57296d89679333ce24e4b64
Merge "Utilizes assertIn and assertNotIn"