fixes tests using called_once_ without assert

A few tests were using mock's called_once, or called_once_with_args
instead of assert_called_once or assert_called_once_with_args. Those
methods return a bool that needs to be actively checked.

The tests are fixed to avoid them from passing if the call condition
is not met.

Change-Id: I21e5257b26b2a08cc8f0b108233d1d5cc0b97b89
Closes-bug: #1297875
(cherry picked from commit c6c4a20777921dc1b21e80edb96ccd957a054c68)
Merge "fixes tests using called_once_ without assert" into milestone-proposed