add automatic tests for AllTracksProxyModel and AllTracksModel
Summary: add automatic tests for AllTracksProxyModel and AllTracksModel
Test Plan: the tests are OK but the windows version still shows no tracks in all tracks views
Reviewers: Elisa, astippich
Reviewed By: Elisa, astippich
Subscribers: astippich
Differential Revision: https://phabricator.kde.org/D11451