REGRESSION TESTING Software Quality Engineering NC Zunaira Tariq Bese 19B Software Quality Engineering NC Zunaira Tariq Bese 19B

We Will Discuss:  What is Regression testing?  Why do we Perform it?  When do we Perform it?  How do we perform it?  What is Regression testing?  Why do we Perform it?  When do we Perform it?  How do we perform it?

What is Regression Testing?  The selective retesting of a software system that has been modified to ensure that any bugs have been fixed and that no other previously working functions have failed as a result of the reparations and that newly added features have not created problems with previous versions of the software.

Why do we need it?  Because when you Fix one bug, you sometimes introduce several other bugs.

Types:  Regular Regression Testing : is done between test cycles to ensure that the defect fixes that are done and the functionality that were working with the earlier test cycle continue to work.  Final Regression Testing: performed to validate the build that hasn’t changed for a period of time. This build is deployed or shipped to customers.  Regular Regression Testing : is done between test cycles to ensure that the defect fixes that are done and the functionality that were working with the earlier test cycle continue to work.  Final Regression Testing: performed to validate the build that hasn’t changed for a period of time. This build is deployed or shipped to customers.

When to use it?  The change is in requirements and the code is modified according to the requirement.  Defect fixing.  New feature is added to the software.  Performance issue fix.  The change is in requirements and the code is modified according to the requirement.  Defect fixing.  New feature is added to the software.  Performance issue fix.

How to perform Regression Testing?  Performing an initial “Smoke” or “Sanity” test  Understanding the criteria to select the test cases for Regression Testing  Prioritization of test cases  Methodology for select test cases  Resetting the test cases for test execution  Concluding the result of a regression test cycle  Performing an initial “Smoke” or “Sanity” test  Understanding the criteria to select the test cases for Regression Testing  Prioritization of test cases  Methodology for select test cases  Resetting the test cases for test execution  Concluding the result of a regression test cycle

Step 1: Perform a Smoke\Sanity Test  Smoke tests done to demonstrate stability, not to find bugs.  Sanity tests done to check if the major functionality of the system is working or not.  Smoke tests done to demonstrate stability, not to find bugs.  Sanity tests done to check if the major functionality of the system is working or not.

Step 2: Choose test case selection criteria  Requires knowledge on the bug fixes and how it affects the system.  Includes the area of frequent defects.  Includes the area which has undergone many/recent code changes.  Includes the area which is highly visible to the users.  Includes the core features of the product which are mandatory requirements of the customer.  Requires knowledge on the bug fixes and how it affects the system.  Includes the area of frequent defects.  Includes the area which has undergone many/recent code changes.  Includes the area which is highly visible to the users.  Includes the core features of the product which are mandatory requirements of the customer.

Step 3: Prioritization of Test Cases  Priority-0: Sanity test cases. also run when a project goes through major changes. deliver a very high project value.  Priority-1: Uses the basic and normal setup and these test cases deliver high project value to both development teams and customers.  Priority-2: These test cases deliver moderate project value and are executed as a part of software testing life cycle and selected for regression on need basis.

Step 4: Test case selection methodology Several approaches:

Continued.. Alternative methodologies:  Regress All: For regression testing, all priority 0, 1, and 2 test cases are re-run.  Priority bases Regression: For regression testing, based on the priority, all priority 0, 1, and 2 test cases are run in order, based on the availability of time.  Random Regression: Random test cases are selected and executed.  Regress Changes: Code changes are compared to the last cycle of testing and test cases are selected based on their impact on the code.  An effective regression strategy is usually a combination of all of the above. Alternative methodologies:  Regress All: For regression testing, all priority 0, 1, and 2 test cases are re-run.  Priority bases Regression: For regression testing, based on the priority, all priority 0, 1, and 2 test cases are run in order, based on the availability of time.  Random Regression: Random test cases are selected and executed.  Regress Changes: Code changes are compared to the last cycle of testing and test cases are selected based on their impact on the code.  An effective regression strategy is usually a combination of all of the above.

Step 5: Resetting test cases for execution Resetting of the test cases need to be done with the following considerations:  When there is a major change in the product.  Where there is a situation, the expected results of the test cases could be quite different from previous cycles.  Whenever existing application functionality is removed, the related test cases can be reset.  When there is a change in the build procedure which affects the product.  Large release cycle where some test cases were not executed for a long time.  You are in the final regression test cycle with a few selected test cases. Resetting of the test cases need to be done with the following considerations:  When there is a major change in the product.  Where there is a situation, the expected results of the test cases could be quite different from previous cycles.  Whenever existing application functionality is removed, the related test cases can be reset.  When there is a change in the build procedure which affects the product.  Large release cycle where some test cases were not executed for a long time.  You are in the final regression test cycle with a few selected test cases.

Step 6: Concluding the Results In situations where the pass % is not 100, test manager looks at previous results:  If the result of a test case was PASS using the previously and FAIL in the current build, then regression failed. get a new build. start testing from scratch.  If the result of a test case was a FAIL using the previous builds and a PASS in the current build, then bug fixes worked.  If the result of a test case was a FAIL previously and a FAIL in the current build then result of this test case shouldn’t be considered for the pass %. such test cases shouldn’t be selected for regression. In situations where the pass % is not 100, test manager looks at previous results:  If the result of a test case was PASS using the previously and FAIL in the current build, then regression failed. get a new build. start testing from scratch.  If the result of a test case was a FAIL using the previous builds and a PASS in the current build, then bug fixes worked.  If the result of a test case was a FAIL previously and a FAIL in the current build then result of this test case shouldn’t be considered for the pass %. such test cases shouldn’t be selected for regression.

QUESTIONS?