I'm developing a hybrid cordova app that should work offline as well. It just caches the data fetched from the network and re-uses the cached version if offline.
Since it's a cordova app, the dev files are on my machine and the url embedded in the app is pointed to my machine, so turning on airplane mode will stop the app to even pull the source code files to start with.
I'm trying to find out what's the approach to develop and test the offline behavior as you code.