White box testing

White Box Testing
Purvi Sankhe

Software Testing
Two Techniques:
1. White Box Testing
2. Black Box Testing
2

 White-box testing
 Tests that concentrate on close examination of
procedural details are conducted
 Logical paths through the software are tested
 Test cases exercise specific sets of conditions and
loops
3
Testing Techniques

Testing Techniques contd..
 Black-box testing
 Tests are conducted to see if specified functions for
which product has been designed is fully operational and
error free
 Tests conducted at the software interface
 Tests related to internal logical structure of the software
are not conducted
4

White-box Testing
 Uses the control structure part of component-level design to derive
the test cases
 These test cases
 Guarantee that all independent paths within a module have
been exercised at least once
 Exercise all logical decisions on their true and false sides
 Execute all loops at their boundaries and within their
operational bounds
 Exercise internal data structures to ensure their validity
6

Basis Path Testing
 White-box testing technique proposed by Tom McCabe
 Enables the test case designer to derive a logical complexity
measure of a procedural design
 Uses this measure as a guide for defining a basis set of execution
paths
 Test cases derived to exercise the basis set are guaranteed to
execute every statement in the program at least one time during
testing
7

Flow Graph Notation
 A circle in a graph represents a node, which stands for a sequence of
one or more procedural statements
 A node containing a simple conditional expression is referred to as a
predicate node
 Each compound condition in a conditional expression containing
one or more Boolean operators (e.g., and, or) is represented by a
separate predicate node
 A predicate node has two edges leading out from it (True and
False)
8

Flow Graph Notation
 An edge, or a link, is a an arrow representing flow of control in a
specific direction
 An edge must start and terminate at a node
 An edge does not intersect or cross over another edge
 Areas bounded by a set of edges and nodes are called regions
 When counting regions, include the area outside the graph as a region,
too
9

Flow Graph Example
10
1
2
0
3
4
5
6
7 8
9
1011
1
2
3
46
7 8 5
9
1011
R1
R2
R3
R4
FLOW CHART FLOW GRAPH
0

Independent Program Paths
 Defined as a path through the program from the start node until the end node that
introduces at least one new set of processing statements or a new condition (i.e., new
nodes)
 Must move along at least one edge that has not been traversed before by a previous
path
 Basis set for flow graph on previous slide
 Path 1: 0-1-11
 Path 2: 0-1-2-3-4-5-10-1-11
 Path 3: 0-1-2-3-6-8-9-10-1-11
 Path 4: 0-1-2-3-6-7-9-10-1-11
 The number of paths in the basis set is determined by the cyclomatic complexity
11

Cyclomatic Complexity
 Provides a quantitative measure of the logical complexity of a program
 Defines the number of independent paths in the basis set
 Provides an upper bound for the number of tests that must be conducted to ensure all
statements have been executed at least once
 Can be computed three ways
 The number of regions
 V(G) = E – N + 2, where E is the number of edges and N is the number of nodes in graph
G
 V(G) = P + 1, where P is the number of predicate nodes in the flow graph G
 Results in the following equations for the example flow graph
 Number of regions = 4
 V(G) = 14 edges – 12 nodes + 2 = 4
 V(G) = 3 predicate nodes + 1 = 4 12

Deriving the Basis Set and Test
Cases
1) Using the design or code as a foundation, draw a corresponding
flow graph
2) Determine the cyclomatic complexity of the resultant flow graph
3) Determine a basis set of linearly independent paths
4) Prepare test cases that will force execution of each path in the
basis set
13

A Second Flow Graph Example
14
1 int functionY(void)
2 {
3 int x = 0;
4 int y = 19;
5 A: x++;
6 if (x > 999)
7 goto D;
8 if (x % 11 == 0)
9 goto B;
10 else goto A;
11 B: if (x % y == 0)
12 goto C;
13 else goto A;
14 C: printf("%dn", x);
15 goto A;
16 D: printf("End of listn");
17 return 0;
18 }
3
4
5
6
7
16
17
8
9
11
12
14
15
13
10

A Sample Function to Diagram and Analyze
15
1 int functionZ(int y)
2 {
3 int x = 0;
4 while (x <= (y * y))
5 {
6 if ((x % 11 == 0) &&
7 (x % y == 0))
8 {
9 printf(“%d”, x);
0 x++;
1 } // End if
2 else if ((x % 7 == 0) ||
3 (x % y == 1))
4 {
5 printf(“%d”, y);
6 x = x + 2;
7 } // End else
8 printf(“n”);
9 } // End while
0 printf("End of listn");
1 return 0;
2 } // End functionZ

A Sample Function to Diagram and Analyze
16
1 int functionZ(int y)
2 {
3 int x = 0;
4 while (x <= (y * y))
5 {
6 if ((x % 11 == 0) &&
7 (x % y == 0))
8 {
9 printf(“%d”, x);
0 x++;
1 } // End if
2 else if ((x % 7 == 0) ||
3 (x % y == 1))
4 {
5 printf(“%d”, y);
6 x = x + 2;
7 } // End else
8 printf(“n”);
9 } // End while
0 printf("End of listn");
1 return 0;
2 } // End functionZ
3
4
6 7
9
10
12 13
15
16
18
20
21

Graph Matrices
17
 To develop s/w tool that assist in basis path testing, a DS called graph
matrix is quite useful.
 Is a square matrix whose size is equal to no of nodes on the flow
graph
 Each node is identified by nos. & each edge is identified by letters
 Letter entry is made to correspond to a connection between two
nodes.
 Link weights is a 1 or 0. (connection matrix)
 Provides other way to determine cyclomatic complexity

White box testing

More Related Content

What's hot (20)

Similar to White box testing (20)

Recently uploaded (20)

White box testing