White box testing involves designing test cases based on examining the internal structure and logic of a program. This includes: 1) Statement testing to execute all statements in a program. 2) Branch/decision testing to execute all outcomes of logical decisions. 3) Branch condition combination testing to test all combinations of conditions in decisions. 4) Modified condition combination testing to independently test each condition in decisions. 5) Loop testing to execute loops at their boundaries and within operational bounds. White box testing aims to thoroughly exercise a program's control flow and internal logic to uncover defects, whereas black box testing focuses only on inputs and outputs without examining internal structure. White box testing generally achieves higher coverage

1. SOFTWARE QUALITY
ASSURANCE
WHITE BOX
Seminar: Oana FEIDI
Quality Manager – Continental Automotive

2. BLACK-BOX VS. WHITE-BOX
 Test cases derived from specifications
 The focus is not the design, nor the implementation
 The focus is on the logic of implementation

3. WHITE BOX (STRUCTURAL
TESTING)
 Structural - test case selection is based on an
analysis of the internal structure of
component
 Control flow
 Statement testing
 Branch/Decision Testing
 Branch Condition Testing
 Modified Condition Combination Testing
 Data flow testing

4. WHITE BOX
 Using the white-box testing techniques outlined
in this seminar, a software engineer can design
test cases that
 exercise independent paths within a module or unit;
 exercise logical decisions on both their true and false side;
 execute loops at their boundaries and within their
operational bounds
 exercise internal data structures to ensure their validity

5. STATEMENT TESTING
 uses a model of the program’s control flow
 it is designed in order to execute all or selected statements of the
test object
Test cases are design to execute
each statement.
An entity in a programming
For each test case specify: language which is typically
the smallest indivisible unit of
• the input(s) of the component execution.
• identification of statement(s) to be
executed by the test case
• the expected outcome of the test
case
Test completeness criteria: the percentage of the statements in the
software which were executed at least at once (executing a statement
means that the statement was encountered and evaluated during testing).

6. EXAMPLE
float foo (int a, int b, int c, int d, float e)
{
float e;
if (a == 0) {
return 0;
}
int x = 0;
if ((a==b) OR ((c == d) AND bug(a) )) {
x=1;
}
e = 1/x;
statement
return e;
}

7. BRANCH/DECISION TESTING
 uses a model of the program’s flow
 it is designed in order to execute (each) outcome
of all or selected decision points in a test object
an executable statement
For each test specify:
which may transfer control
• the input(s) of the component to another statement,
depending upon the logic
• Identification of decision
of the decision statement
outcome(s) to be executed by
the test case
• the expected outcome of the
test case
Test completeness criteria: achievement of the test coverage – 100%
of the branches (one true and one false for each part of condition)

8. EXAMPLE
A = true and (B or C) = false
 A = false and (B or C) = true
if A and (B or C)
Case A B C Output
1 0 1 1 0
2 1 0 0 0

9. BRANCH CONDITION COMBINATION
 uses a model of the program flow where each
combination of the inputs for a decision/condition must
be tested, in order to check if each branch is covered
 For each test case specify:
 the input(s) of the component
 the expected outcome of the test case which can show which
branch is covered
Test completeness criteria: for a condition containing n
boolean operands → 2n test cases are required to achieve
100% coverage
Note: this coverage rapidly becomes unachievable for more
complex conditions.

10. WHITE BOX - SUMMARY
 Statement testing
 uses a model of the program’s control flow
 it is designed in order to execute all or selected statements of
the test object
 Branch/Decision Testing
 uses a model of the program’s flow
 it is designed in order to execute (each) outcome of all or
selected decision points in a test object
 Branch Condition Combination
 uses a model of the program flow where each combination
of the inputs for a decision/condition must be tested, in
order to check if each branch is covered

11. MODIFIED CONDITION COMBINATION
TESTING
 usesa model of the program’s flow where each
atomic condition is independently tested, in order
to show how the decision outcome is affected
 test
case are designed to show that each condition
independently affects the decision outcome
 For each test case specify:
 the input(s) of the component
 The expected outcome of the test case

12. MODIFIED CONDITION COMBINATION
TESTING
 Test completeness criteria
 for a condition containing n boolean operands, to achieve
100% coverage are necessary:
 minimum: n + 1 test cases
 maximum: 2n test cases
 Example: for 3 boolean operands, to achieve 100%
coverage are necessary:
 Minimum 4 test cases
 Maximum 6 test cases

13. EXAMPLE
Case A B B or C C Outcome
1 1 1 1 0 1 if (A and (B or C))
2 0 0
3 1 1 1 0 1
4 0 0 0
5 1 0 1 1 1
6 0 0 0

14. LOOP TESTING
 Simple Loops:- 'n' is the maximum number of allowable
passes
 skip the loop entirely.
 only one pass thru the loop.
 two passes thru the loop.
 m passes thru the loop where m< n.
 n-1,n,n+1 passes thru the loop
 Nested loops
 start with the innermost loop. Set all other loop to min. values.
 conduct simple loop tests for the innermost loop while holding the
outer loops at their min. iteration values.
 work outward, conducting tests for the next loop, but keeping all
the outer loops at their min. iteration count.
 continue until all loops have been tested.

15. EXERCISE
 1) Identify what scenarios have to be run to achieve
100% statement coverage and 100% branch coverage
on the following code
 2) Test the same examples on the following link.
Does white-box covers 100% the black-box?