The testing of combined parts of an application to determine if they function correctly together is Integration Testing.
Need of Integration Testing:
Although each software module is unit tested, defects still exist for various reasons like:
A Module in general is designed by an individual software developer who understanding and programming logic may differ from other programmers.
Integration testing becomes necessary to verify the software modules work in unity
at the time of module development, there wide chances of change in requirements by the clients.
These new requirements may not be unit tested and hence integration testing becomes necessary.
Interfaces of the software modules with the database could be erroneous 4. External Hardware interfaces, if any, could be erroneous
Inadequate exception handling could cause issues.
Methods of doing Integration Testing
Integration testing begins with unit testing, followed by tests of progressively higher-level combinations of units called modules or builds.
Integration testing, the highest-level modules are tested first and progressively lower-level modules are tested after that.