1. 1 A Survey of Unit Testing Practices Prof. Per Runeson – Lund University Per Beremark – SPIN-syd

2. 2 What is Unit Testing? “testing of individual software or hardware units or groups of related units” [IEEE610.12] “Unit testing tests individual software components or a collection of components. Testers define the input domain for the units in question and ignore the rest of the system. Unit testing sometimes requires the construction of throwaway driver code and stubs and is often performed in a debugger” [Whittaker 00] “a test, executed by the developer in a laboratory environment, that should demonstrate that the program meets the requirements set in the design specification” [Koomen and Pol 00]

3. 3 What Does It Mean In Practice? 1.What do people refer to as unit testing? 2.What are the strengths regarding unit testing in industry? 3.Which are the problems regarding unit testing?

4. 4 Key Findings on Unit Testing What? –Technical! –Specified or not? How? –Structure-based –Not formally Who? –Developer (team) –Not test or QA When? –Each build/day/week –Takes seconds to hours to run Why? –Assuring functionality

5. 5 Participants: SPIN-syd of Southern Sweden 19 companies –Telecom –Automation –Case tools –Information systems –Banking –Health care –Consulting –Transportation Company size –1-1000 developers 17 participants in focus group 15 in questionnaire

6. 6 Survey Procedures Unit testing is… Unit testing -What -Strengths -Problems Analysis -What? -How? -Where? -Who? Q’s Note 1. Individual reflection 2. Focus group discussion Note 3. Document and structure 4. Analysis 5. Survey preparation 6. Survey conduct 7. Survey analysis Q&A’s Note

7. 7 3rd party verification Unit test – smallest specified unit Test first Training Focus Group Meeting

8. 8 Analysis Framework What? How? Where? Who? When? Why? Unit test

9. 9 Questionnaire

10. 10 Analysis

11. 11 What? Definition –Test of smallest unit or units Strength –Unit identification –Test of surrounding modules Weaknesses –GUI test –Unit identification –Test scripts and harness maintenance –Data structures

12. 12 How? Definition –Structure-based –Preferably automated Strength –Test framework Weaknesses –Documentation –Framework tailoring –Test selection –Test metrics

13. 13 Who? Definition –By developer Strength –Independent test –Competence network Weaknesses –Competency –Independence –Introduction strategy

14. 14 When? Definition –Quick feedback Strength –Continuous regression test Weaknesses –Stopping criteria

15. 15 Why? Definition –Ensure functionality Strength –External requirement (safety) –Agile methods Weaknesses –Cost vs. value

16. 16 Further Use of the Survey Clarify unit test definition in your company Lightweight assessment of unit testing practices –Benchmark –Improve

17. 17 Read more… … in IEEE Software July/August 2006

18. 18 http://serg.telecom.lth.se

19. 19 Definitions

20. 20 Strengths and weaknesses