There is no general test. A home for the elderly in Gothenburg with about 70 employees is trailing shortening working hours. It's done as a test to see how it affects productivity, working environment etc, and meant to serve as basis for future political decisions.

In Swedish: http://arbetet.se/2015/08/03/112559/

There's also a few other tests around Swedn but overall I guess way less than 1k people.