There are several ways to test the builds for Android TV. The obvious and simplest one is to use an emulator.

Emulators for Android TV—as for phones—are virtual machines that run exactly the same version of the operating system as the real device. Therefore they are very reliable but also quite slow.

Of course, ideally you should be able to test your game on a real device. At the time of writing, there are several smart TVs announced with Android TV, but the best devices to test are the ADT-1 (Developer Kit) and the Nexus Player.

ADT-1 however is in short supply and is hard to get. The Nexus Player on the other hand is a fairly cheap device.

However, unless you require to test gameplay, navigation can be easily tested with an emulator.

Note that emulators do not include Google Play Services but a real device will have them.

I also noticed that the theme on the ADT-1 is slightly different...