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Whitebox Testing

http://flic.kr/p/ ohtmj. Whitebox Testing. SWEBOK Knowledge Areas. Software Requirements Software Design Software Construction Software Testing Software Maintenance Software Configuration Management Software Engineering Management Software Engineering Process

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Whitebox Testing

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  1. http://flic.kr/p/ohtmj Whitebox Testing

  2. SWEBOK Knowledge Areas • Software Requirements • Software Design • Software Construction • Software Testing • Software Maintenance • Software Configuration Management • Software Engineering Management • Software Engineering Process • Software Engineering Models and Methods • Software Quality • Software Engineering Professional Practice • Software Engineering Economics • Computing Foundations • Mathematical Foundations • Engineering Foundations Today’s topic

  3. Recall: Common approaches forchoosing test cases • Blackbox testing: Choose based on module’s possible inputs and outputs • Do not use code • Often test boundary cases • White-box testing: Uses internal logic to choose tests • Different levels of code coverage • Aka glass box testing, clear box testing • Regression testing: Keep tests that reveal old bugs • Rationale: “Fixed” bugs come back!

  4. Criteria for choosing test cases:Coverage Measures • Degree to which the source code of a program is tested by a test suite • Examples: • Statement coverage • Condition coverage • Path coverage Some examples will clarify, but first…

  5. Control Flow Graphs –Frequently used to calculate coverage Control Flow Graph int foo(int x, int y) { int z = 0; if ((x>0) && (y>0)) { z = x; } return z; } int z = 0; if ((x>0) && (y>0)) { true z = x; false return z; Basic blocks: straight-line pieces of code without any jumps or jump targets Jumps: control branches

  6. Statement Coverage • Set of test cases such that…Each program statement (line or basic block) is executed at least once

  7. Define a test suite that provides statement coverage for this code int foo(int x, int y) { int z = 0; if ((x>0) && (y>0)) { z = x; } return z; } ✔ Control Flow Graph int z = 0; if ((x>0) && (y>0)) { ✔ true z = x; ✔ false return z;

  8. Now try this code… public int bar(int x) { int result=0; if (x < 69) { if (x % 2 == 0) { result = x/2; } else { result = x*2; } } else if (x > 6969) { x = 69; } else { x = 6969; } return result; } Control Flow Graph int result=0; result = x*2; F T x < 69 x % 2 == 0 T F result = x/2; T x > 6969 x = 69; F return result; x = 6969;

  9. Now try this code… Control Flow Graph ✔ ✔ int result=0; result = x*2; ✔ F ✔ T x < 69 x % 2 == 0 T ✔ F result = x/2; ✔ ✔ T x > 6969 x = 69; ✔ F return result; ✔ x = 6969;

  10. Condition Coverage • Set of test cases such that…Each boolean expression (in control structures) evaluates to true at least once and to false at least once

  11. Define a test suite that provides condition coverage for this code int foo(int x, int y) { int z = 0; if ((x>0) && (y>0)) { z = x; } return z; } Control Flow Graph ✔ int z = 0; if ((x>0) && (y>0)) { ✔ true z = x; false return z;

  12. Now try this code… public int bar(int x) { int result=0; if (x < 69) { if (x % 2 == 0) { result = x/2; } else { result = x*2; } } else if (x > 6969) { x = 69; } else { x = 6969; } return result; } Control Flow Graph int result=0; result = x*2; F T x < 69 x % 2 == 0 T F result = x/2; T x > 6969 x = 69; F return result; x = 6969;

  13. Now try this code… Control Flow Graph int result=0; result = x*2; ✔ ✔ F T x < 69 x % 2 == 0 ✔ T ✔ F result = x/2; ✔ T x > 6969 x = 69; ✔ F return result; x = 6969;

  14. Path Coverage • Set of test cases such that…Each possible path through a program’s control flow graph is taken at least once

  15. Define a test suite that provides path coverage for this code int foo(int x, int y) { int z = 0; if ((x>0) && (y>0)) { z = x; } return z; } Control Flow Graph int z = 0; if ((x>0) && (y>0)) { (c) (a) true (b) z = x; false return z; • Paths: • a , b • c ✔ ✔

  16. Now try this code… public int bar(int x) { int result=0; if (x < 69) { if (x % 2 == 0) { result = x/2; } else { result = x*2; } } else if (x > 6969) { x = 69; } else { x = 6969; } return result; } Control Flow Graph int result=0; result = x*2; F T x < 69 x % 2 == 0 T F result = x/2; T x > 6969 x = 69; F return result; x = 6969;

  17. Now try this code… Control Flow Graph int result=0; result = x*2; (a) (f) F T • Paths: • a , d , f , h • a , d , g , i • a , b , e , j • a , b , c , k x < 69 (d) x % 2 == 0 ✔ (h) T (g) ✔ (b) F ✔ result = x/2; ✔ (i) T x > 6969 x = 69; (e) (j) F (c) return result; (k) x = 6969;

  18. BONUS QUESTION

  19. Given this code • Draw a control flow graph • Define test suites that provide: • Statement coverage • Condition coverage • Path coverage int myF(int x, int y) { while (x > 10) { x = x – 10; if (x == 10) { break; } } if (y < 20 && x%2 == 0) { y = y + 20; } else { y = y – 20; } return 2*x + y; }

  20. int myF(int x, int y) { while (x > 10) { x = x – 10; if (x == 10) { break; } } if (y < 20 && x%2 == 0) { y = y + 20; } else { y = y – 20; } return 2*x + y; } while (x > 10) F T x = x – 10; if (x == 10) F T break; if (y < 20 && x%2 == 0) F T y = y – 20; y = y + 20; return 2*x + y; Here’s the CFG

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