I have seen many testers not concentrating on negative test cases. I insist every QA to test for negative test cases first and then start with positive test cases. No network connection test cases are one of them. So things which you need to keep in mind while testing for No network connections are below.
Disconnect the Internet and launch the application:
On tapping any button ex: Sign-in button, No internet connection alert has to be displayed.
Please Note: Its not a good practice to display the alert as soon you launch the application. Display the alert only when you tap on any button. The only exception is when you are downloading any assets from the server.
Display timeout alert:
If your internet connection is very slow then you may observe in some application that activity indicator would remain in the screen throughout and the only way you can access the application is by relaunching the application through force quit. So it's better to display a timeout alert when downloading takes a lot of time. A good practice is to keep the timeout as 30 secs or allow the user to return back to the previous screen when the activity indicator is on the screen.
Check if the content is getting downloaded on connecting back to the internet:
Consider this example, you are on a screen and your WiFi gets turned off by itself. Now you receive a No internet connection dialog box as downloading of content was stopped. Now connect back to WiFi and check if contents are displayed on tapping the tab again or if the screen is reloaded.
Check if Game Center/Flurry data is updated after connecting back to the internet:
Developers have to make sure that they have to store data of Game center/Flurry when the user is playing in offline mode. When the user connects back to the Internet and checks Game Center application, data of achievement and Leaderboard should get updated. Similarly with Flurry events.
Check my other post related to Game Center in iOS
http://qualitytesting1.blogspot.in/2013/08/game-center-in-ios.html
Check for the content that requires server support:
Any content which saves data in Server shouldn't be allowed to edit while using the application in offline mode. Ex: Profile of the user
Disconnect the Internet and launch the application:
On tapping any button ex: Sign-in button, No internet connection alert has to be displayed.
Please Note: Its not a good practice to display the alert as soon you launch the application. Display the alert only when you tap on any button. The only exception is when you are downloading any assets from the server.
Display timeout alert:
If your internet connection is very slow then you may observe in some application that activity indicator would remain in the screen throughout and the only way you can access the application is by relaunching the application through force quit. So it's better to display a timeout alert when downloading takes a lot of time. A good practice is to keep the timeout as 30 secs or allow the user to return back to the previous screen when the activity indicator is on the screen.
Check if the content is getting downloaded on connecting back to the internet:
Consider this example, you are on a screen and your WiFi gets turned off by itself. Now you receive a No internet connection dialog box as downloading of content was stopped. Now connect back to WiFi and check if contents are displayed on tapping the tab again or if the screen is reloaded.
Check if Game Center/Flurry data is updated after connecting back to the internet:
Developers have to make sure that they have to store data of Game center/Flurry when the user is playing in offline mode. When the user connects back to the Internet and checks Game Center application, data of achievement and Leaderboard should get updated. Similarly with Flurry events.
Check my other post related to Game Center in iOS
http://qualitytesting1.blogspot.in/2013/08/game-center-in-ios.html
Check for the content that requires server support:
Any content which saves data in Server shouldn't be allowed to edit while using the application in offline mode. Ex: Profile of the user