All you need to know about Regression testing| David Tzemach 1. Overview 2. What is “Regression” testing…? 3. When should you use it..? 4. How to implement..? 5. Test Recommendations 6. Considerations when building Regression tests

1. ALL YOU NEED TO
KNOW ABOUT
REGRESSION TESTING
DAVID TZEMACH
WWW.DTVISIONTECH.COM
JAN 23 2016

2. OVERVIEW
THE PROBLEM WE HAVE AS SOFTWARE TESTERS, IS THAT THE LIFE CYCLE OF
A SOFTWARE IS A VERY DYNAMIC. THEREFORE, EVERY PART IN CODE MAY
CHANGE AND LEAD TO A NEW RISKS THAT ALREADY REMOVED DURING THE
PREVIOUS TESTING CYCLES.
THE SOLUTION FOR OVERCOMING THIS PROBLEM IS TO USE THE TESTING
METHOD OF “REGRESSION TESTING” THAT PROVIDE A GREAT SOLUTION TO
HANDLE THESE NEW RISKS

3. DEFINITION OF “REGRESSION” TESTING
THE MOST SIMPLIFIED DEFINITION OF THIS TESTING METHOD, IS THAT WE
USE IT TO “VALIDATE A FUNCTIONALITY THAT WAS ALREADY WORKING AND
TESTED BY THE QA TEAM, STILL WORKS AFTER A NEW CODE THAT WAS
ADDED OR AN OLD CODE THAT WAS MODIFIED”

4. WHEN TO USE THIS TESTING METHOD..?
YOU SHOULD USE REGRESSION TESTS, WHENEVER YOU HAVE RISK THAT A SOFTWARE
THAT ALREADY TESTED MAY BE AFFECTED BY A NEW CODE THAT WERE
ADDED/CHANGED, EXAMPLES:
• A NEW FEATURE THAT WAS ADDED.
• BUG FIXES.
• CHANGES IN ORIGINAL REQUIREMENTS.
• NEW REQUIREMENTS ADDED.
• NEW PATCHES OR UPDATED.

5. THE FLOW OF
REGRESSION TESTS

6. PHASE 1: ANALYZE THE CHANGE
IN THIS PHASE YOU NEED TO ANALYZE HOW THE NEW CODE THAT WERE
ADDED/MODIFIED IS AFFECTING THE APPLICATION, TO ACCOMPLISH THIS TASK, PLEASE
ANSWER THIS BASIC QUESTION:
• HOW THIS CHANGE EFFECT PREDEFINED TESTS FOR THE ORIGINAL CODE?
• IS THERE ANY INTEGRATED CODE THAT IS AFFECTED BY THE CHANGE?
• WHICH AREAS ARE MOST LIKELY TO BE AFFECTED BY THE CHANGE?
• HOW THIS CHANGE EFFECT THE SOFTWARE DOCUMENTATION?

7. PHASE 2: THE TESTING STRATEGY
BASED ON THE RISK THAT YOU ANALYZED ON PHASE 1, YOU HAVE THE FULL INFORMATION THAT
YOU NEED TO DETERMINE WHAT IS THE TESTING EFFORT THAT YOU NEED TO REMOVE THE RISK:
TEST THE ENTIRE CODE - THIS STRATEGY IS THE BEST WHEN YOU HAVE THE TIME, MONEY AND
HIGHLY TRAINED AUTOMATION TEAM THAT ALLOWING YOU TO RUN THE ENTIRE TEST PLAN
INCLUDING THE OLD AND NEW TESTS.
TESTING DONE IN HIGH RISK AREAS- THIS STRATEGY WILL BE USED WHEN THE TESTING TEAM
IDENTIFIES THE AREAS THAT MOST LIKELY AFFECTED FROM THE CHANGE AND PROBABLY CONTAIN
THE BIGGER RISKS.

8. PHASE 3: HOW TO RUN YOUR TESTS?
THE TEST EXECUTION CAN BE ACCOMPLISHED IN 3 DIFFERENT WAYS:
MANUAL TESTS – MANUAL TESTERS WILL RUN THE SELECTED TESTS MANUALLY, BUT FOR ME, IT’S
THE LESS PREFERRED WAY TO HANDLE THIS TYPE OF TESTS.
AUTOMATED TEST - THIS IS MY PREFERRED WAY, ALL TESTS WILL RUN AUTOMATICALLY AND
WITHOUT A MAJOR INTERFERING OF THE MANUAL TESTERS.
AUTOMATION AND MANUAL TESTING – COMBINATION OF THE TWO WORLDS, OLD TESTS WILL BE
COVERED BY AUTOMATION, THE NEW TESTS WILL BE COVERED MANUALLY.

9. PHASE 4: REPORTING
THE TESTING RESULTS PER REGRESSION CYCLE SHOULD BE
REPORTED AND ANALYZED, ACCORDING TO FAILURES, WE CAN
ADD/REMOVE/MODIFY TESTS TO INCREASE THE EFFICIENCY OF
FUTURE TESTING CYCLE.

10. CONSIDERATIONS
WHEN BUILDING
REGRESSION TESTS

11. WHAT IS THE TESTING COVERAGE..?
WE ARE USING REGRESSION TESTS TO VALIDATE THAT NOTHING IS BROKEN
IN THE APPLICATION WHEN CODE MODIFICATIONS ARE DONE, THIS FACTOR
HAS A MAJOR EFFECT ON WHAT COVERAGE DO WE WANT TO HAVE,
SHOULD WE ADD EVERY TESTS TO THE REGRESSION CYCLES OR NARROW IT
TO A SPECIFIC SET OF TEST CASES…?

12. HOW MUCH EFFORT IS NEEDED ..?
ASK YOURSELF THIS QUESTIONS:
1. WHAT IS THE AMOUNT OF TIME THAT IT WILL TAKE TO CREATE THE REGRESSION TESTS..?
2. WHAT IS THE AMOUNT OF TIME THAT IT WILL TAKE TO EXECUTE THE REGRESSION TESTS..?
3. WHAT ARE THE COSTS OF THIS EFFORT (BASED ON THE ANSWERS THAT YOU PROVIDE ON
Q1/2)..?

13. MAINTENANCE
CREATING THE REGRESSION TEST PLAN, IS PROBABLY THE EASY PART, THE
HARD PART IS TO MAKE SURE THAT THIS TESTS WILL REMAIN UPDATED
PERVERSION, THEREFORE, YOU NEED TO MAKE SURE THAT YOU
UNDERSTAND THE IMPACT OF THE MAINTENANCE COSTS AND THE EFFORT
THAT IT WILL TAKE FROM YOUR TEAM.

14. TEST PRIORITIZATION
REGRESSION TESTS MAY INCLUDE THOUSANDS OF TEST CASES, IN SOME
SITUATIONS YOU SIMPLY DON’T HAVE THE TIME TO EXECUTE THEM ALL.
THEREFORE, YOU MUST PRIORITIZE THE TESTS TO RUN IN THE ORDER THAT
WILL GUARANTEE THAT YOU COVER THE MOST CRUCIAL TESTS FIRST.

15. CAN YOU AUTOMATE..?
CAN YOU AUTOMATE YOUR TESTS OR NOT..? THE ANSWER TO THIS
QUESTION WILL DETERMINE HOW MANY TESTS YOU CAN WRITE
AND RUN PER TESTING CYCLE.

16. FOR ADDITIONAL KB’S PLEASE
VISIT MY BLOG
WWW.DTVISIONTECH.COM