Reject non existent mock assert calls

assert_called and assert_not_called are not asserting the state
of the mock object but considered as mocked calls so mock
will never raise exception but always executed successfully

This change patches the Mock class during unit test
to raise an exception if a function called on a mock object
that's name starts with 'assert' and does not one
of the supported Mock assert calls.

This change also fix the unit test to call only the supported
assert function on mock object.

Change-Id: I036587f355e42e362ac2b70fb6755cca81d30b75
Merge "Reject non existent mock assert calls"