1. White-Box Testing
Pfleeger, S. Software Engineering Theory and Practice 2nd Edition. Prentice Hall, 2001.
Ghezzi, C. et al., Fundamentals of Software Engineering. Prentice Hall, 2002.
Pressman, R., Software Engineering A Practitioner’s Approach, Mc Graw Hill, 2005.
1209

2. White Box Testing Also known as:
Glass box testing
Structural testing
Test set is derived from structure of code
Code structure represented as a Control Flow Graph
Goal is to cover the CFG

3. Control Flow Graphs
Programs are made of three kinds of statements:

4. Control Flow Graph (CFG)
Sequence
If-then-else
If-then
Iterative

5. Example 1: CFG 1. read (result); 2. read (x,k)
3. while result < 0 then {
4. ptr  false
5. if x > k then
ptr  true
7. x  x + 1
8. result  result + 1 }
9. print result

6. Write a CFG Example 2 1. if (a < b) then 2. while (a < n)
a  a + 1;
4. else
while (b < n)
b  b + 1;

7. Answers Example 3 1. read (a,b); 2. if (a  0 && b  0) then {
c  a + b;
if c > 10 then
c  max
else c  min }
7. else print ‘Done’

8. Answers Example 4 1. read (a,b); 2. if (a  0 || b  0) then {
c  a + b
while( c < 100)
c  a + b; }
6. c  a * b

9. Cyclomatic Complexity
Software metric for the logical complexity of a program.
Defines the number of independent paths in the basis set of a program
Provides the upper bound for the number of tests that must be conducted to ensure that all statements been have executed at least once
For Edges (E) and Nodes (N)
V(G) = E – N + 2

10. Complexity of CFGs
3,4
3,4 1 1 5 5 6 2
Join
Join 3

11. Example 1
2,3 6
4,5 8 7 9 10 11

12. Example 1: CFG
1,2 3 9
4,5 6
Join
7,8

13. Example 2 1 2 3
Join 5 6

14. Answers
1,2
Join
3,4 5 6 7

15. Answers
1, 2 3
Join 4 5 6

16. Criteria Statement coverage Branch coverage Condition coverage
(lots of others …)

17. Branch Coverage
Each edge of a program’s CFG is traversed at least once in some test.
Independent paths:
1, 2, 3, 9
1, 2, 3, 4, 5, 6, 7, 8, 3, …, 9
1, 2, 3, 4, 5, 7, 8, 3, …, 9 3
4,5 6
Join 9
7,8
1,2
Example 1
P353 Pfleeger 2nd ed

18. Criteria Statement coverage Branch coverage Condition coverage
Every complex condition is made true and false by every possible combination
E.G., (x and y)
x = true, y = true
x=false, y=true
x = true, y= false
x =false, y = false

19. AND Condition
1, 2A 2B 4 3
Join

20. OR Condition
1,2A 3 2B 4 5
Join

21. Path Coverage-1
Every distinct path through code is executed at least once
Basis set does not yield minimal test set
Example
1. read (x)
2. read (z)
3. if x  0 then begin
y  x * z;
x  z end
6. else print ‘Invalid’
7. if y > 1 then
8. print y
9. else print ‘Invalid’
Test Paths:
1, 2, 3, 4, 5, J1, 7, 8, J2
1, 2, 3, 4, 5, J1, 7, 9, J2
1, 2, 3, 6, J1, 7, 8, J2,
1, 2, 3, 6, J1, 7, 9, J2
1,2,3
4,5 6
Join1
P353 Pfleeger 2nd ed 7 8 9
Join2

22. Def-Use Coverage 1,2,3 Example 4,5 6 Join 7 8 9 Join
Def-use coverage: every path from every definition of every variable to every use of that definition is exercised in some test.
Example
1. read (x)
2. read (z)
3. if x  0 then begin
y  x * z;
x  z end
6. else print ‘Invalid’
7. if y > 1 then
8. print y
9. else print ‘Invalid’
1,2,3
Def: x, z
Use: x
Def: y, x
Use: x, z
4,5 6
Use: none
Join 7
Use: y 8 9
Use: none
Use: y
Test Path: 1, 2, 3, 4, 5, 7, 8, J
Join

23. Strength of Coverage

24. What paths don’t tell you
Timing errors
Unanticipated error conditions
User interface inconsistency (or anything else)
Configuration errors
Capacity errors