1. White Box Testing
by :
Andika Bayu H

2. Introduction White Box Testing or Glass Box Testing
Test case design method that uses the control structure of the procedural design to derive test cases
SW Engineer can derive test cases that
guarantee that all independent paths within a module have been exercised at least once
exercise all logical decisions on their true and false bounds
execute all loops at their boundaries and within their operational bounds
exercise internal data structures to assure their validity
Why not just validate the requirement ?
Logic errors and incorrect assumptions are inversely proportional to the probability that a program path will be executed
We often believe that a logical path is not likely to be executed when, in fact, it may be executed on a regular basis
Typographical errors are random

3. Basis Path/Control Structure Testing
Proposed by Tom McCabe
The basis path method enables the test case designer to derive a logical complexity measure of a procedural design and use this measure as a guide for defining a basis set of execution paths
Flow Graph Notation:

4. Pseudo Code - Flow Chart
Procedure Sort
Flow Chart
Procedure Sort
1. do while not eof
2. Read Record
3. if record field 1 = 0
4. then process record
store in buffer;
increment counter
7. else if record field 2 = 0
then reset counter
else process record
store in file
endif
12. endif
13. enddo

5. Flow Chart - Flow Graph
Flow Chart
Flow Graph

6. Compound Logic
IF a or b
then procedure X
else procedure Y
endif

7. Cyclomatic Complexity ( V(G) )
software metric that provide a quantitative measure of the logical complexity of a program]
V(G) = E - N + 2
V(G) =
= 3
The number of regions of the flow graph correspond to the cyclomatic complexity.
V(G) = P + 1, where P is the number of predicate nodes

8. Independent Path path 1: 1-13 path 2: 1-2-3-7-8-11-12-1-13
An independent path is any path through the program that introduces at least one new set of processing statements or a new condition
An independent path must move along at least one edge that has not been traversed before the path is defined
path 1: 1-13
path 2:
path 3:
path 4:
Is the path
an independent path ?

9. Deriving Test Cases
Draw a corresponding flowgraph using the design or code as a foundation
Determine the cyclomatic complexity of the resultant flow graph (V(g))
Determine a basis set of linearly independent paths
Prepare test cases that will force execution of each path in the basis set
if we have 6 independent paths, then we should have at least 6 test cases. For each test cases, we should define
the input conditions and
the expected result.

10. Graph Matrices
Can automate derivation of flow graph and determination of a set of basis paths.
Software tools to do this can use a graph matrix.
Graph matrix:
is square with #sides equal to #nodes
Rows and columns correspond to the nodes
Entries correspond to the edges.
Can associate a number with each edge entry.
Use a value of 1 to calculate the cyclomatic complexity
For each row, sum column values and subtract 1.
Sum these totals and add 1.

11. Some other interesting link weights:
Probability that a link (edge) will be executed
Processing time for traversal of a link
Memory required during traversal of a link
Resources required during traversal of a link

12. Loop Testing Loop is fundamental to many algorithms.
Loop can be defined as simple, concatenated, nested, and unstructured.

13. Loop Testing (2) Simple Loops of size n: Nested Loops
To test:
Simple Loops of size n:
Skip loop entirely
Only one pass through loop
Two passes through loop
m passes through loop where m<n.
(n-1), n, and (n+1) passes through the loop.
Nested Loops
Start with inner loop. Set all other loops to minimum values.
Conduct simple loop testing on inner loop.
Work outwards
Continue until all loops tested.
Concatenated Loops
If independent loops, use simple loop testing.
If dependent, treat as nested loops.
Unstructured loops
Don't test - redesign.