Cyclomatic complexity

1. Cyclomatic complexity White Box Testing

2. Correctness tests dan path coverage • Path yang berbedadalammodul software akandibentukolehpilihankondisional statement seperti IF-THEN-ELSE atau DO WHILE atau DO UNTIL atau REPEAT-UNTIL

3. McCabe’s cyclomatic complexity metric • Dikembangkan oleh McCabe (1976) untuk mengukur kompleksitas program atau modul pada waktu yang sama sebagai jumlah maksimum independent path yang dibutuhkan untuk mencapai full line coverage pada program. • Dasar ukuran adalah teori graf dan dihitung berdasarkan kesesuaian ke sifat program yang dicapture oleh program flow graph • Independent path adalah setiap path pada program flow graph sedikitnya satu baris yang tidak dibentuk oleh independent path lain.

4. A 20 times B Example How many test cases ?

5. Structural test - Control graph(Static point of view) 1 2 3 4 5 Example : if ( a > b and b > c) then max=a; else max = 100; end if ; 0 1 1 1 2 3 3 3 3 4 4 4 4 4 5 6 7 7 8 9 10 11 12 12 13 14 14 15 16 16 17 18 18 19 void main (void) { int a, b, c; int min, med, max; if (a>b) { max=a; min=b; } else { max=b; min=a; } if (c>max) {max=c;} else if (c<min) {min=c;} med=a+b+c-min-max; if (max>min+med) {printf("impossible triangle \n");} else if (max==min) {printf("equilateral triangle \n");} else if (max==med || med==min) {printf("isoceles triangle \n");} else if ( max *max == min*min+med*med) {printf("rightangled triangle\n");} else {printf("any triangle\n");} } 7 6 8 9 10 v(G) = 25 - 19 + 2 = 8 8 Path = ?? 11 12 14 13 16 15 17 18 19

6. RUMUS • V(G) = R • V(G) = E – N +2 • V(G) = P + 1 • Keterangan • V(G) = cyclometic complexity metric • R = jumlah region dalam program flow graph • Setiap area yang melingkungi graph disebutsebuah region • E = Jumlah Edge (garis) • N = Jumlah node • P= Jumlah decision

7. Structural test - Simple control structures(Static point of view) 1 1 1 2 3 2 2 3 3 if... else... v(G)=2 if... .. v(G)=2 4 while ... v(G)=2

8. b d e c f g Structural test - Independence of control paths(Static point of view) a v(g)=10-7+2=5 This graph has 5 independent paths: C1 abcbcg C2 abefg C3 adfg C4 adefg C5 abcg All the other paths are derived from the preceding 5 by linear combination example: abcbcbefg=C1+C1+C2-C5-C5

9. 1 2 4 3 5 6 7 8 Path coverage testing Next, we derive the independent paths: Since V(G) = 4, there are four paths Path 1: 1,2,3,6,7,8 Path 2: 1,2,3,5,7,8 Path 3: 1,2,4,7,8 Path 4: 1,2,4,7,2,4…7,8 Finally, we derive test cases to exercise these paths, i.e. choose inputs that lead to traversing the paths

10. White BoxLogic-Coverage Testing Statement coverage Decision coverage Condition coverage Decision-condition coverage Multiple-condition coverage

11. Consideration • complete path testing is not a realistic goal for a program with loops.

12. Statement coverage (1/3)

13. Statement Coverage (2/3) • writing a single test case that traverses path ace. • by setting A=2, B=0, and X=3 at point a, • Every statement would be executed once (actually, X could be assigned any value).

14. Statement Coverage (3/3) • Unfortunately, this criterion is a rather poor one. • Perhaps the first decision should be an or rather than an and • Perhaps the second decision should have stated X>0 • Also, there is a path through the program in which X goes unchanged (the path abd) • the statement coverage criterion is so weak that it generally is useless.

15. decision coverage orbranch coverage. • This criterion states that you must write enough test cases that each decision has a true and a false outcome at least once. • each branch direction must be traversed at least once. • Decision coverage usually can satisfy statement coverage.

16. decision coverage orbranch coverage. • decision coverage requires that each decision have a true and a false outcome, and • that each statement be executed at least once. • has to be modified for programs that contain multiway decisions. • Java programs containing select (case) statements,

17. decision coverage orbranch coverage. • decision coverage can be met by two test cases covering paths • ace and abd or, • alternatively, acd and abe • A = 3, B = 0, X = 3 • A = 2, B = 1, and X = 1.

18. decision coverage orbranch coverage. • stronger criterion than statement coverage, • but it still is rather weak. • there is only a 50 percent chance that we would explore the path where X is not changed (abd) • only if we chose the former alternative • ace and abd

19. Condition Coverage • A criterion that is sometimes stronger than decision coverage is condition coverage. • write enough test cases to ensure that each condition in a decision takes on all possible outcomes at least once. • this does not always lead to the execution of each statement, • an addition to the criterion is that each point of entry to the program or subroutine, as well as ON units, be invoked at least once.

20. Condition Coverage • Figure 4.1 has four conditions: A>1, B=0, A=2, and X>1. • enough test cases are needed to force the situations where A>1, A<=1, B=0, and B<>0 are present at point a and • where A=2, A<>2, X>1, and X<=1 are present at point b. • 1. A=2, B=0, X=4 ace • 2. A=1, B=1, X=1 abd

21. Condition Coverage • Alternative • 1. A=1, B=0, X=3 • 2. A=2, B=1, X=1 • cover all condition outcomes, • but they cover only two of the four decision outcomes. • both of them cover path abe

22. decision/condition coverage. • requires sufficient test cases that each condition in a decision takes on all possible outcomes at least once, • Each decision takes on all possible outcomes at least once, • and each point of entry is invoked at least once.

23. decision/condition coverage • A weakness with decision/condition coverage is that, • although it may appear to exercise all outcomes of all conditions, • it frequently does not because certain conditions mask other conditions.

25. Figure 4.2 is the way a compiler would generate machine code • A more thorough test coverage, appears to be the exercising of all possible outcomes of each primitive decision • The two previous decision coverage test cases do not accomplish this; they fail to exercise the false outcome of decision H and the true outcome of decision K.

26. Multiple Condition Coverage • This criterion requires that you write sufficient test cases that all possible combinations of condition outcomes in each decision, and all points of entry, are invoked at least once.

27. Multiple Condition Coverage • It should be easy to see that a set of test cases satisfying the multiple condition criterion also satisfies • the decision-coverage, • condition coverage, • and decision/condition-coverage criteria.

28. Multiple Condition Coverage

29. Multiple condition Coverage • These combinations to be tested do not necessarily imply that eight test cases are needed. • In fact, they can be covered by four test cases. • A=2, B=0, X=4 Covers 1, 5 • A=2, B=1, X=1 Covers 2, 6 • A=1, B=0, X=2 Covers 3, 7 • A=1, B=1, X=1 Covers 4, 8

30. Multiple condition Coverage • The fact that there are four test cases and four distinct paths in Figure 4.1 is just coincidence. • In fact, these four test cases do not cover every path; • they miss the path acd.

31. ConclusionLogic Coverage vs Path • In the case of loops, the number of test cases required by the multiple-condition criterion is normally much less than the number of paths.