This week's book giveaway is in the Design forum. We're giving away four copies of Experimentation for Engineers: From A/B testing to Bayesian optimization and have David Sweet on-line! See this thread for details.
That should work in the emulator, but how are you turning the network off? Did you press the F8 key in the emulator?
Also, did you request the ACCESS_NETWORK_STATE permission in your AndroidManifest.xml file?
Lastly, you may want to use just isConnected() instead. The NetworkInfo may report true for isConnectedOrConnecting() when the network connections appear to be possible but even if you aren't able to use it yet. I also found a post that suggested using isAvailable() as well in your checks.