log-writer: add some tests
log-writer: add some tests

Acidburn0zzz/worker,Acidburn0zzz/worker,travis-ci/worker,henrikhodne-abandoned/worker,solarce/worker,solarce/worker,solarce/worker,travis-ci/worker,henrikhodne-abandoned/worker,henrikhodne-abandoned/worker,travis-ci/worker,Acidburn0zzz/worker