Lecture 15 - Software Testing (Part II)

Testing Techniques

Black Box Testing

Black box testing can be referred to as:

• Functional Testing
• Opaque Testing
• Closed Box Testing

Black Box Test design is usually described as focusing on testing functional requirements. Knowing the specified function that the product has been designed to perform , test can be conducted to demonstrate that each function is fully operational at the same time searching for errors in that function.

Since the system is black box its behavior can only be determined by studying its inputs and the related outputs.

The outcome of black box testing will be compared with the expected outcome which was generated by using the systems specification.



White Box Testing

White box testing can be referred as;

• Structural Testing
• Glass Box Testing
• Clear Box Testing

White box test design allows one to peak inside the function and it focuses specifically on using internal knowledge of the software, to guide the selection of test data. Knowing the internal working of a product, test can be conducted to ensure that the internal operations perform according to the specification.


White box testing confirms the following:

• All independent paths written in a module have been exercised at least once.
• Check all logical operations for their true false options Exercise internal data structures to ensure their validating.
• Exercise all the loops within their boundaries.

Static Verification
The process whereby programmers read the program before they are tested by running the code on computer can be categorized into two sections.

• Desk checking
• Dry Run

Desk Checking
Desk checking is used test the actrons or process of a program and should be carried out with the following guide lines. Desk checking is done by a manager or supervisor of work, who goes through the following items and report error to ihe programmer.

• Variable List
• Subroutines / Functions
• Constants
• Equation of variables

The next test after performing the desk check for the program design is dry running the corresponding code.

Dry Running
Dry running a program segment involves the execution of the segment with the programmer acting as a computer. The success of the technique depends updn the ability to simulate the computer's action wiihout making any assumption at all. The dry run table should have separate columns for the following instructions.

• Each instruction working
• Each variable declaration
• Each data structure such as arrays, linked Iist etc.

This is used to test the logic of the program.

V-Model (Link between design and testing)