In the current world of various operating systems, browser versions and fast growing variants of platforms it is very important for a development team to ensure that their product/application is compatible with all those platforms/configurations product is expected to work on.
Initial step towards compatibility testing is to define the set of platforms the application is expected to work on. Based on the planned configuration test team should arrange to bifurcate them in to following and arrange for the test environments;
Various Hardware Configurations
Different Operating Systems / Platforms
Various Network Environments
Various Computer Peripherals (Printers, Zip drives, USBs, etc.)
Various Third-party Software (Browsers, Firewalls, Network, Multimedia plug-ins, etc.)
Some of the important factors to be considered during Compatibility testing are;
Browser/Platform features which might add an extra feature to the application. Hence while testing on particular browser/platform Tester must be aware about all the add-on feature of that browser/platform
Some of the actions of the application taken by the Tester may not be supported by the browser/platform under test which generally results in incomplete functional operations without getting the desired result.
Sometimes due to lack awareness about features of different browser/platform, Testers are mislead into the belief of getting defect/error in the application even though its not.
There are many other things that can be considered during compatibility testing which can show the difference of browser/platform used for testing with reference to the functional operation of the application under test.
The Compatibility Testing has to be executed by expert team based on the region targeted and the domain specifics. Initial round of Compatibility test would take one week or more based on the application size and number of platforms to be covered within.