Rajiv Chopra - Software Testing

SOFTWARE
TESTING

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SOFTWARE
TESTING

A Self-Teaching Introduction

RAJIV CHOPRA, PhD

MERCURY LEARNING AND INFORMATION

Dulles, Virginia
Boston, Massachusetts
New Delhi

Copyright 2018 by MERCURY LEARNING AND INFORMATION LLC. All rights reserved.

Original Title and Copyright: Software Testing, 4/e. 2014 by S.K. Kataria & Sons.

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R. Chopra. Software Testing: A Self-Teaching Introduction.
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CONTENTS

CHAPTER 1

INTRODUCTION TO SOFTWARE TESTING

Inside this Chapter:

1.0. INTRODUCTION

Testing is the process of executing the program with the intent of finding faults. Who should do this testing and when should it start are very important questions that are answered in this text. As we know software testing is the fourth phase of the software development life cycle (SDLC). About 70% of development time is spent on testing. We explore this and many other interesting concepts in this chapter.

1.1. THE TESTING PROCESS

Testing is different from debugging. Removing errors from your programs is known as debugging but testing aims to locate as yet undiscovered errors. We test our programs with both valid and invalid inputs and then compare our expected outputs as well as the observed outputs (after execution of software). Please note that testing starts from the requirements analysis phase only and goes until the last maintenance phase. During requirement analysis and designing we do static testing wherein the SRS is tested to check whether it is as per user requirements or not. We use techniques of code reviews, code inspections, walkthroughs, and software technical reviews (STRs) to do static testing. Dynamic testing starts when the code is ready or even a unit (or module) is ready. It is dynamic testing as now the code is tested. We use various techniques for dynamic testing like black-box, gray-box, and white-box testing. We will be studying these in the subsequent chapters.

1.2. WHAT IS SOFTWARE TESTING?

The concept of software testing has evolved from simple program check-out to a broad set of activities that cover the entire software life-cycle.

There are five distinct levels of testing that are given below:

a. Debug: It is defined as the successful correction of a failure.

b. Demonstrate: The process of showing that major features work with typical input.

c. Verify: The process of finding as many faults in the application under test (AUT) as possible.

d. Validate: The process of finding as many faults in requirements, design, and AUT.

e. Prevent: To avoid errors in development of requirements, design, and implementation by self-checking techniques, including test before design.

There are various definitions of testing that are given below:

Testing is the process of exercising or evaluating a system or system component by manual or automated means to verify that it satisfies specified requirements.

[IEEE 83a]

OR

Software testing is the process of executing a program or system with the intent of finding errors.

[Myers]

OR

It involves any activity aimed at evaluating an attribute or capability of a program or system and determining that it meets its required results.

[Hetzel]

Testing is NOT:

a. The process of demonstrating that errors are not present.

b. The process of showing that a program performs its intended functions correctly.

c. The process of establishing confidence that a program does what it is supposed to do.

So, all these definitions are incorrect. Because, with these as guidelines, one would tend to operate the system in a normal manner to see if it works. One would unconsciously choose such normal/correct test data as would prevent the system from failing. Besides, it is not possible to certify that a system has no errorssimply because it is almost impossible to detect all errors.