White Box Testing
• Software testing method in which the internal design/implementation that is , the internal logic of the item
being tested should be known to the tester.
• A tester, usually a developer as well, studies the implementation code of certain module and hence decides all
valid and invalid inputs to cover the paths through the code and determine the appropriate outputs and
verifies them.
White Box Testing: Steps
• Source code understanding
 To understand the source code of the application being tested.
 The tester should know the programming language that is being used in developing the application.
 The tester should know the internal structure of the code.
• Creation and execution of test cases
 To write test cases based on Statement/Decision/Condition/Branch coverage &
 actual execution of test cases for maximum testing coverage of the software application.
White Box Testing: Code coverage techniques
• Statement Coverage
 Whitebox testing technique where every statements, i.e each and every line of code is executed at least
once during the testing process.
• Branch/Decision Coverage
 Branch coverage covers every possible path ( true/false, or if-else and other conditional loops ).
 It covers all the possible outcomes of each condition at least once.
 It ensures that every possible branch from each decision point in the code is executed at least once.
• Path Coverage
 Every path is executed at least once.
 It ensures that every statement in the program is guaranteed to be executed at least one time.
• Other Coverage techniques
 Condition coverage, Multiple Condition coverage, Function coverage, etc.
White Box Testing: Code coverage Example
False
True
C1
A
B
if condition C1
then
operation A
else
operation B
endif
C2
if condition C2
then
operation C
True
False
C
White Box Testing: Code coverage Example
False
True
C1
A
B
if condition C1
then
operation A
else
operation B
endif
C2
if condition C2
then
operation C
True
False
C
Testcase1: Execute operation A
condition C1 = True.
Testcase2: Execute operation B
condition C1 = False.
White Box Testing: Code coverage Example
False
True
C1
A
B
if condition C1
then
operation A
else
operation B
endif
C2
if condition C2
then
operation C
True
False
C
Testcase3: Execute operation C
condition C2 = True.
White Box Testing: Code coverage Example
False
True
C1
A
B
if condition C1
then
operation A
else
operation B
endif
C2
if condition C2
then
operation C
True
False
C
Test cases = 3
Testcase
C1
C2
1
True
X
2
False
X
3
X
True
White Box Testing: Code coverage Example
False
True
C1
A
B
if condition C1
then
operation A
else
operation B
endif
C2
if condition C2
then
operation C
True
False
C
Test cases = 2
Testcase
C1
C2
1
True
True
2
False
True
Case3 same as Case1, with C2 = True.
White Box Testing: “Statement coverage” Example
if condition C1
then
operation A
else
operation B
if condition C1
then
operation A
else
operation B
endif
endif
if condition C2
then
operation C
if condition C2
then
operation C
Testcase
C1
C2
Testcase
C1
C2
1
True
True
2
False
True
White Box Testing: Code coverage Example
False
True
C1
A
B
if condition C1
then
operation A
else
operation B
endif
C2
Branch not
covered
if condition C2
then
operation C
True
False
C
Test cases = 3
Testcase
C1
C2
1
True
True
2
False
True
C2 = False. (Condition not covered)
White Box Testing: “Branch coverage” Example
False
True
C1
A
B
if condition C1
then
operation A
else
operation B
endif
C2
Branch
covered
if condition C2
then
operation C
True
False
C
Test cases = 3
Testcase
C1
C2
1
True
True
2
False
True
3
False
False
White Box Testing: “Branch coverage” Example
True
False
C1
C1
A
B
C2
False
C1
A
B
True
C2
A
B
True
C2
False
C
C
C
White Box Testing: “Path coverage” Example
True
C1
A
B
Test cases = 4
C2
False
C
Testcase
C1
C2
1
True
True
2
False
True
3
False
False
4
True
False
Missing Path covered.
White Box Testing
• Complexity
 The complexity or the number of factors involved depends upon the application being tested.
• Whitebox testing does not necessarily show if the program does work along the
functional requirement or not, but it does show what the developer wanted.
• Here comes in the Blackbox testing.
• It is based on Requirement specifications, also known as Behavioral Testing, is a
software testing method in which the internal structure/ design/ implementation
of the item being tested is not known to the tester.