Differences in Mobile and Desktop Application Testing

How would you test a ‘Mobile’ version of IM?开发者_JAVA技巧 What are some key differences between testing this version versus a desktop application?

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First of all you need to account for unstable connectivity - the program should be ready to deal with temporary and permanent network coverage losses.

Resources consumption (memory footprint, network bandwidth and CPU time) is also to be considered. Noone wants a program that drains the battery in an hour, occupies all memory or causes a giant bill to the owner.

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Both memory requirement and network bandwidth has to be kept to as low as possible...

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adding to sharptooth's answer, notifications on sending/receiving a message. Support for voice chat/video chat via available hardware :)