Regression Testing

REGRESSION TESTING

1. The word regress means to return to the previous.                                         

2. Regression testing refers to that portion of the test cycle in which a program q is tested to ensure that not only the newly added or modified code behaves correctly but also that code carried over unchanged from the previous version p continue to behave correctly.

3. Regression testing is also called as program "revalidation".

4. The term corrective regression testing refers to regression testing of a program obtained by making corrections

5. Regression testing is also needed when a subsystem is modified to generate a new version of an application.

REGRESSION TEST PROCESS:

Test revalidation/selection/minimization/prioritization   ------->2.Testsetup------>3.Test sequencing------->4.fault mitigation------>5.Output comparison------>6.Test execution

The steps in brief: -

1. Test revalidation/selection/minimization/prioritization:

->Test revalidation refers to the task of checking which test for p remain valid for q. Revalidation is necessary to ensure that only tests are applicable to q are used during regression testing.

->Test selection can be interpreted in several ways. Validation test must be redundant that they do not traverse any modified portions in q.

->Test minimization discards the tests seemingly redundant with respect to some criteria. for eg: if both t1 and t2 test function f in p, then one might decide to discard t2in favor of t1.

PURPOSE: reduce the number of tests

Test prioritization refers to the task of prioritizing test based on criteria. A set of tests become useful only a subset of tests can be executed due to resource constraints.

TEST SETUP:

->It refers to the process by which the application under test is placed in its intended or simulated, environment ready to receive data and able to transfer any desired output information.

->Test setup process and the setup itself are highly dependent on the application under test and its hardware and software environments.

TEST SEQUENCING:

->The sequence in which tests are input to an application may be concern.

->Test sequencing often becomes important for an application that has an internal state and is continuously running.

->Eg: ATM cash withdrawal.

TEST EXECUTION:

->Once the testing infrastructure has been setup, tests selected, revalidated and sequenced, it is time to execute them.

->The importance of a tool for test execution cannot be overemphasized.