Software TestingWhite Box Testing

Agenda

• What is White Box Testing

• Correctness Tests and Path Coverage

• Correctness Tests and Line Coverage

• McCabe Cyclomatic Complexity

• Software Qualification and Reusability Testing

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Test

Mappin

g

3

Test classificationMcCall Req. Model

White Box Testing

Black Box Testing

Output Correctness Tests +

Documentation Tests +

Availability Tests +

Data Processing and Calculation Correctness +

Software Qualification Tests +

Reliability Tests +

Stress Tests +

Software System Security Tests +

Training Usability Tests +

Operational Usability Tests +

Maintainability Tests + +

Flexibility Tests +

Testability Tests +

Portability Tests +

Reusability Tests +

Software Interoperability Tests +

Equipment Interoperability Tests +

White Box Testing – Data Processing and Calculation Correctness

Data processing and calculation correctness tests

• Every operation in the sequence created by each test case (path) must be tested

• Done to verify whether processing operations and their sequences were programmed correctly

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White Box Testing – S/W Qualification

Software Qualification Tests

• Examine software code including comments

• Comply with the coding standard and work instructions

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White Box Testing – Maintainability

Maintainability Tests

• Check special features

• Installed for detection of causes of failure

• Modules to support software adaptation

• Modules to support software improvements

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White Box Testing – Reusability

Reusability Tests

• Extent of reuse software integrated in the software

• Adaptations performed to make the reusable component work with the project

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• Check data processing for each test case

• Coverage

Path Coverage: Test cases should cover all paths.

Coverage is the percentage of paths covered from the

total

Line Coverage: Test all program code lines. Coverage is

the percentage of lines covered.

Data Processing & Calculation Correctness

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Path Coverage

9IF – THEN - ELSE

LOOP

Paths are created in a program whenever we use looping

statements or conditional statements

• Test completeness is the percentage of paths

executed during the test.

• Sometimes impractical to test all paths.

• Example:

Imagine a program with 10 conditional statements with

two options = 1024 different paths.

25-50 lines of code has 1024 test cases

Path Coverage

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• Every line of code be executed at least once during

the process of testing.

• Completeness of line testing is the percentage of

lines executed during tests.

Line Coverage

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Path coverage using flowchart

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1. Charge min fare

2. DIST3 4

5. WAIT

8. SUIT

6 7

910

11. Print Receipt

D > 1000 D <= 1000

W > 3 W <= 3

S > 1 S <= 1

Path coverage using flowchart

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Test Case Path 2.

Dist5.

Wait 8. Suit

1 1-2-3-5-6-8-9-11 T T T

2 1-2-3-5-6-8-10-11 T T F

3 1-2-3-5-7-8-9-11 T F T

4 1-2-3-5-7-8-10-11 T F F

5 1-2-4-5-6-8-9-11 F T T

6 1-2-4-5-6-8-10-11 F T F

7 1-2-4-5-7-8-9-11 F F T

8 1-2-4-5-7-8-10-11 F F F

x = No. of decision elementsNo. of Paths = 2x (Max)

Line coverage using flow graph

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1

2

3 4

6 7

5

8

9 10

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Line coverage using flow graph

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Test Case Path

1 1-2-3-5-6-8-9-11

2 1-2-4-5-7-8-10-11

Proportion of Test Cases

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Line Coverage Path Coverage

2 8

1 : 4For each line coverage, I have four paths.

• Maximum paths needed for full line coverage

• No. of independent paths needed

Based on Graph Theory

Graph Elements

N is the Number of Nodes

E is the Number of Edges

P is the Number of Decision Elements (2 arrows leaving the element)

Formula

V(G) = E - N + 2

V(G) = P + 1

McCabe’s Cyclomatic Complexity

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For example

V(G) = 13-11+2 = 4 V(G) = 3+1 = 4

Definition

Any path on the program flow graph that includes at least one edge

that is not included in any of the former independent paths

It is defined in reference to the previous independent paths gathered

Independent Path

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Path Edges addedNo. of edges

added

1-2-3-5-6-8-9-111-2, 2-3, 3-5, 5-6, 6-8, 8-9, 9-11

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1-2-4-5-6-8-9-11 2-4, 4-5 2

1-2-3-5-7-8-9-11 5-7, 7-8 2

1-2-3-5-6-8-10-11 8-10,10-11 2

Program Complexity

Based on empirical results (repeated experiments)

Cyclomatic Complexity

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McCabe CC Program Complexity

< 5Simple, Easy to understand

>=5 && < 10 Not too difficult

> 20 High

> 50 Untestable

S/W Qualification Testing

Code should be written according to standards – easier to check the

software.

Easier to debug, update the code in maintenance and understand by

new programmers.

Questions

Does the code follow the structure – module size, use of reused code

Is the coding style according to guidelines?

Is the internal program documentation according to the procedure

defined?

Qualification Tests

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Can be done automatically or manually

If manually, need Code Auditors

Advantages

Reduces project resource requirements

Improve quality of new systems

Shortens the development time

What is done?

Packages and documentation for reuse conform to standard and

procedures

Reusability Tests

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White Box Testing

Advantages

• Direct statement-by-statement testing

• Check algorithms are correctly defined and coded

• List of paths / lines that are not executed or covered by test cases

• Measure coding quality

• Adherence to coding standards

Disadvantages

• Vast resources needed

• Cannot test performance in terms of availability (response

time) Reliability Load durability

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When to use- High Risk Modules- High Cost of Failure