Unit Testing : This is done in Development System, Unit testing should be taken care of by the developer at the developer side by executing the test scripts which are provided by functional peoples to trace the errors like if its not meeting the reqs or any bugs is there.

Integration Testing : This is done in QA System, Integration testing is being done by functional folks after deliverable by the developer to test whether its working up to the point and after integrating this module with any other module, what are the errors. generating.

Regression Testing : The term “regression testing” can be applied two ways. First, when a code problem has been fixed, a regression test runs tests to verify that the defect is in fact fixed; “Imagine finding an error, fixing it, and repeating the test that exposed the problem in the first place. This is a regression test” (Kaner in Testing Computer Software). Second, regression testing is the counterpart of integration testing: when new code is added to existing code, regression testing verifies that the existing code continues to work correctly, whereas integration testing verifies that the new code works as expected. regression testing can describes the process of testing new code to verify that this new code hasn’t broken any old code.