what should be tested test planning should also look at all aspects of the software under test for functionalityusabilitylegal complianceconformance to regulatory constraintssecurityperformanceavailabilityresilienceetc testing should be driven by the need to identify and reduce risk testing software systems as indicated above there are number of different types of testing that are commonly used within industry these types areunit testingwhich is used to verify the behaviour of individual components integration testing that tests that when individual components are combined together to provide higher-level functional unitsthat the combination of the units operates appropriately regression testing when new components are added to systemor existing components are changedit is necessary to verify that the new functionality does not break any existing functionality such testing is known as regression testing performance testing is used to ensure that the systemsperformance is as required andwithin the design parametersand is able to scale as utilisation increases stability testing represents style of testing which attempts to simulate system operation over an extended period of time for examplefor online shopping application that is expected to be up and running stability test might ensure that with an average load that the system can indeed run hours day for days week