1 Software Testing Dr. Xin (Judy) Feng Web:

2 Introductory Stuff  Have Fun!  Please turn off your phones!  DO  DO interact with me!

3 Introductory Stuff  This will be a relatively interactive course. Feel free to stop me, shout at me, argue, … etc.  If you have trouble understanding me (I expect that you will), TELL ME!  I will try to speak more clearly and slowly!

4 Outline  What is software testing  Why do we need the testing  How should we do the testing  Basic testing strategies

5 What is software testing?  Software Testing is an activity to catch bugs in software applications (include Computer-Aided Language Learning applications)

6 Why software testing?  Create robust products  Reduce the risks (time, money, life, credit … ) What problems do you think are bugs in a CALL system?

7 Some misunderstandings about software testing Testing is Debugging??? Truth:  Testing is to show that programs have bugs  Debugging is to find the errors that make the programs fail

8 Some misunderstandings about software testing Testing is Easy??? Truth:  Testing is very expensive. It consumes almost half of the labour in the software development

9 Some misunderstandings about software testing Testing is Everything??? Truth:  Testing is one of the activities to assure software quality  Other activities are necessary

10 How to test software?  Test cases used to input to a system to check if the system produces an unexpected result  Two basic testing strategies White-box testing Black-box testing

11 White-box testing  Test cases are generated based on the internal structure and code of programs  Basic white-box testing strategies Statement testing Branch testing Path testing

12 White-box testing Count spelling errors and grammar errors Spelling errors > 10 Deduct 10 marks Grammar errors > 5 Deduct 15 marks Statement Branch Path

13 Statement testing Count spelling errors and grammar errors Spelling errors > 10 Deduct 10 marks Grammar errors > 5 Deduct 15 marks Statement Every statement must be executed at least once. Question: At least how many test cases are needed?

14 Branch testing Count spelling errors and grammar errors Spelling errors > 10 Deduct 10 marks Grammar errors > 5 Deduct 15 marks Branch Every Branch must be executed at least once. Question: At least how many test cases are needed?

15 Path testing Count spelling errors and grammar errors Spelling errors > 10 Deduct 10 marks Grammar errors > 5 Deduct 15 marks Path Every path must be executed at least once. Question: How many paths are there totally?

16 Black-box testing  Test cases are generated based on the program requirements  Basic black-box testing strategies Equivalence-class testing Boundary value testing

17 Equivalence class testing  Categorize the input into the classes with some similar features  Select one or more test cases from each class

18 Equivalence class testing Students’ marks for grammar and spelling Grammar marks > 60 and Spelling marks > 60 Grammar marks > 60 and Spelling marks ≤ 60 Grammar marks ≤ 60 and Spelling marks > 60 Grammar marks ≤ 60 and Spelling marks ≤ 60 Four classes Pass Supplementary for spelling Supplementary for grammar Fail

19 Boundary value testing  Use the boundary values as well as normal values to test  Software applications tend to fail at the boundary values

20 Boundary value testing Spelling marks: 0 – 100 Grammar marks:

21 Summary  Software testing - What, why and how  White-box testing Statement testing Branch testing Path testing  Black-box testing Equivalence class testing Boundary value testing