software methadology

International Journal of Soft Computing and Engineering (IJSCE)

ISSN: 2231-2307, Volume-2, Issue-3, July 2012

251



Abstract— In recent years, software testing is becoming more popular and important in the software development industry.

Indeed, software testing is a broad term encircling a variety of

activities along the development cycle and beyond, aimed at

different goals. Hence, software testing research faces a collection

of challenges. A consistent roadmap of most relevant challenges is

proposed here. In it, the starting point is constituted by some

important past achievements, while the destination consists of two

major identified goals to which research ultimately leads, but

which remains as reachable as goals. The routes from the

achievements to the goals are paved by outstanding research

challenges, which are discussed in the paper along with the

ongoing work.

Software testing is as old as the hills in the history of digital

computers. The testing of software is an important means of

assessing the software to determine its quality. Since testing

typically consumes 40~50% of development efforts, and consumes

more effort for systems that require higher levels of reliability, it is

a significant part of the software engineering

Software testing is a very broad area, which involves many

other technical and non-technical areas, such as specification,

design and implementation, maintenance, process and

management issues in software engineering. Our study focuses on

the state of the art in testing techniques, as well as the latest

techniques which representing the future direction of this area.

Today, testing is the most challenging and dominating activity

used by industry, therefore, improvement in its effectiveness, both

with respect to the time and resources, is taken as a major factor

by many researchers

The purpose of testing can be quality assurance, verification,

and validation or reliability estimation. It is a tradeoff between

budget, time and quality. Software Quality is the central concern

of software engineering. Testing is the single most widely used

approach to ensuring software quality.

(Keywords: SDLC, Software quality, Testing techniq

Technique .)

I. INTRODUCTION

I. Introduction: Software Testing

Software testing is the process of executing a program or

system with the intent of finding errors. Software is not unlike

other physical processes where inputs are received and

outputs are produced. Where software differs is in the manner

in which it fails. Most physical systems fail in a fixed (and

reasonably small) set of ways. By contrast, software can fail in

Manuscript received: on July, 2012

Maneela Tuteja, Department of Information TechnologyDronacharya

College of Engineering, Gurgaon, Haryana,.

Gaurav Dubey, Amity School of Computer Sciences, Amity University,

Uttar Pradesh,India.,

.

many bizarre ways. Detecting all of the different failure

modes for software is generally infeasible.

Discovering the design defects in software, is equally

difficult, for the same reason of complexity. Because software

and any digital systems are not continuous, testing boundary

values are not sufficient to guarantee correctness. All the

possible values need to be tested and verified, but complete

testing is infeasible. Exhaustively testing a simple program to

add only two integer inputs of 32-bits (yielding 2^64 distinct

test cases) would take hundreds of years, even if tests were

performed at a rate of thousands per second.

The iterative process of software testing consists of

1. Designing tests

2. Executing tests

3. Identifying problems.

4. Getting problems fixed.

A. Objective of Testing

The objective of testing is to find problems and fix them to

improve quality. Software testing typically represents 40% of

a software development budget. There are four main

objectives of testing:

(a) Demonstration: It shows that, system can be used for

integration with acceptable risk. It demonstrates

functions under special conditions and shows that

products are ready for integration or use.

(b) Detection: It discovers defects, errors and deficiencies.

Determines system capabilities and limitations quality

of components, work products and the system.

(c) Prevention: It provides information to prevent or reduce

the number of errors clarify system specifications and

performance. Identify ways to avoid risk and problems

in the future.

(d) Improving Quality: By doing effective testing, we can

minimize errors and hence improve the quality of

software.

II. TYPES OF SOFTWARE TESTING

There are various types of testing techniques that have been

invented. Each testing technique serves a different purpose for

testing different artifacts like designing, coding and planning

software requirement specification.

All the testing techniques are divided into mainly three

categories, black box, white box or grey box testing.

Techniques which tests external behavior of the system are

categorized in Black box testing and which tests internal

behavior of the system are termed as white box testing and

A Research Study on importance of Testing and

Quality Assurance in Software Development

Life Cycle (SDLC) Models

Maneela Tuteja, Gaurav Dubey

A Research study on Importance of Testing and Quality Assurance in Software Development Life Cycle (SDLC)

Models

252

which tests both internal and external behavior are called grey

box testing.

Software Testing Techniques

Black

box

Testing

White box

Testing

Grey

box

Testing

Function

al and

system

testing,

Stress

testing,

Performa

nce

testing,

Usability

testing,

Acceptan

ce

Testing,

Beta

testing,

Ad hoc

Testing,

Regressi

on

testing,

Intersyst

em

testing,

Volume

testing,

Parallal

testing,

Boundar

y value

Unit testing,

Error

handling

testing, Desk

checking,

Code walk

through,

Code

reviews and

inspection,

Code

coverage

testing,

Statement/

Path/

Function/

Condition

testing,

complexity

testing/

Cyclomatic

complexity,

Mutation

testing

Integrati

on

Testing,

Regressi

on

Testing.

III. SDLC AND QUALITY ASSURANCE

SDLC refers to software development life cycle, i.e. the

various stages used in the life cycle of software development.

There are various software development approaches defined

and designed which are used during development process of

software, these approaches are also referred as “Software

Development Process Models”.

A. SDLC Models

Software development life cycle is basically a systematic way

of developing software. It includes various phases starting

from the functional requirement of software (means what

software is supposed to do). After that designing takes place

then development and then testing. After testing is finished,

the source code is generally released for Unit Acceptance

Testing (UAT) in client testing environment. After approval

from client, the source code is released into production

environment [1]. There is various software development

approaches defined and designed which are used during

development process of software, these approaches are also

referred as "Software Development Process Models". Each

process model follows a particular life cycle in order to

ensure success in process of software development.

Various types of SDLC Models are :

 Water-fall Model

 Prototype Model

 RAD Model

 V Model

 The waterfall Model

Waterfall approach was first process model to be introduced

and followed widely in software engineering to ensure

success of the project. In "The Waterfall" approach, the

whole process of software development is divided into

separate process phases. The phases in Waterfall model

are: Requirement Specifications phase, Software Design,

Implementation, Testing, Deployment of system &

Maintenance [1]. All these phases are cascaded to each

other so that second phase is started as and when defined set

of goals are achieved for first phase and it is signed off, so

the name “Waterfall Model”. Fig 3.1 shows all the phases in

water fall model.

Com m unic a t ion

Planning

Mode ling

Const r uc t ion De ploy m e nt

analysis

design code

t est

proje c t init ia t ion

re quire m e nt ga t he ring estimating

scheduling

tracking

de liv e ry

s upport

f e e dba c k

Fig (a) : The phases of Waterfall Model

Advantages

In W ater fall model, every phase is implemented in a

sequential order. Waterfall model is used where the duration

of project is very less, and it is best suited for small projects.

Also, Waterfall model is suitable when the specification and

requirements are clearly stated for the software project.

Disadvantages

In Waterfall model, the output of one phase forms the

input of the next phase. This concept actually turns a s i t s

d i s a d v a n t a g e i . e . When a mi s t a k e o c c u r s i n a

particular phase, the same mistakes gets carried over to the

last phase. Waterfall model is time intensive process and

almost provides little or no option to change user

requirements. This model is useful only when the

requirements are free zed.

 The Prototyping Model

A prototype is a working model that is functionally

equivalent to a component of the product. In many instances

the client only has a general view of what is expected from

the software product [27]. In such a scenario where there is

an absence of detailed information regarding the input to the

system, the processing needs and the output requirements,

International Journal of Soft Computing and Engineering (IJSCE)

ISSN: 2231-2307, Volume-2, Issue-3, July 2012

253

the prototyping model may be employed.

Co m m u n icat io n

Q u i ck p l an

Co n st r u ct io n

o f

p r o t o t yp e

Mo d e l i n g

Q u i ck d e si g n

De live r y

& Fe e d b ack

Deployment

Fig. (b) The Prototyping Model

Advantages

With reduced time and costs, Prototyping can improve the

quality of requirements and specifications provided to

developers. Prototyping requires user involvement and

allows them to see and interact with a prototype allowing

them to provide better and more complete feedback and

specifications.

Disadvantages

Insufficient analysis: The focus on a limited prototype can

distract developers from properly analyzing the complete

project. User can begin to think that a prototype, intended

to be thrown away, it is actually a final system that merely

needs to be finished or polished developer attachment to

prototype.

 The Spiral Model The spiral model, also known as the spiral lifecycle model,

is a systems development method (SDM) used in

information technology (IT) [1]. This model of

development combines the features of the prototyping

model and the waterfall model. The spiral model is

intended for large, expensive, and complicated projects.

Fig (c) The Spiral Model

Advantages

Estimates (i.e. budget, schedule, etc.) Become more

realistic as work progresses, because important issues are

discovered earlier. It is more able to cope with the (nearly

inevitab le ) c h a n g e s t h a t software d e v e l o p me n t

generally entails. Software engineers (who can get restless

with protracted design processes) can get their hands in and

start working on a project earlier.

Disadvantages

As it is highly customized so there is limiting re-usability. It

is applied differently for each application. There is a risk of

not meeting budget or schedule.

B. Quality Assurance

Everyone is committed to quality; however, the following

statement shows some of the confusing ideas shared by

many individuals that inhibit achieving a quality

commitment: Quality requires a commitment, particularly

from top management. Close cooperation of management

and staff is required in order to make it happen.

• Many individuals believe that defect-free products and

services are impossible, and accept certain levels of defects

as normal and acceptable [1].

• Quality is frequently associated with cost, meaning that

high quality equals high cost. This is confusion between

quality of design and quality of conformance [2].

• Quality demands requirement specifications in enough

detail that the products produced can be quantitatively

measured against those specifications. Many organizations

a r e n o t capable or willing to expend the effort to

produce specifications at the level of detail required [3].

Technical personnel often believe that standards stifle their

creativity, and thus do not abide by standards compliance.

However, for quality to happen, well-defined standards and

procedures must be followed [1].

Quality cannot be achieved by assessing an already

completed product. The aim therefore, is to prevent quality

defects or deficiencies in the first place, and to make the

products assessable by quality assurance measures. Some

quality assurance measures include: structuring the

development process with a software development standard

and supporting the development process with methods,

techniques, and tools. The undetected bugs in the software

that caused millions of losses to business have necessitated

the growth of independent testing, which is performed by

a company other than the developers of the system [8].

In addition to product assessments, process assessments are

essential to a quality management program. Examples

include documentation of coding standards, prescription

and use of standards, methods, and tools, procedures for data

backup, test methodology, change management, defect

documentation, and reconciliation. Quality management

decreases production costs because the sooner a defect is

located and corrected, the less costly it will be in the long

run [7]. With the advent of automated testing tools, although

the initial investment can be substantial, the long-term result

will be higher-quality products and reduced maintenance

costs. The total cost of effective quality management is

the sum of four component costs: prevention, inspection,

internal failure, and external failure. Prevention costs

consist of actions taken to prevent defects from occurring in

the first place. Inspection costs consist of measuring,

evaluating, and auditing products or services for

conformance to standards and specifications [9]. Internal

A Research study on Importance of Testing and Quality Assurance in Software Development Life Cycle (SDLC)

Models

254

failure costs are those incurred in fixing defective products

before they are delivered.

IV. PROBLEM STATEMENT

A. Problem Definition

The study of various software development process

models reveal that in almost all these models, software

testing is included as one phase, but testing is required at

each phase and not at a particular stage. The main purpose of

software testing is to uncover errors which are not simply

syntax errors in code but various other types of errors in all

the documents produced during the software

development ,e.g. software requirements document, design

document, test plan etc. Various types of software testing

techniques have been developed till date, but which type of

testing technique will be suitable and sufficient for checking

a particular document in which phase of software

development life cycle (SDLC) is not yet clear. So here the

problem is to

1. Identify the testing techniques which can be applied

at different levels and phases of software development

life cycles

Also, software quality is an essential part of any software

project. Various quality assurance and control activities may

be used to ensure quality in the software project. Different

quality attributes need different types of testing to measure

software quality. The problem is that out of numerous

testing techniques possible, which testing technique should

be applied to measure which quality attribute is not very

clear. So the next problem takes here is

2. Identify the testing techniques which can be

applied to measure which software quality attribute

B. Justification

By categorizing which type of testing to be applied at

which phase of software development will help us plan for

testing in that phase efficiently and to take full advantage of

all the types of testing techniques to improve quality in that

phase and consequently the overall quality of the software

project. The relation between various quality attributes and

the testing techniques required for each of these will help

save time and produce quicker results and streamlined

testing of the project for that particular software quality

attribute.

This defines the statement of problem. Next we’ll

describes the Proposed Solutions according to the problem of

statement.

C. Proposed solution

According to the problem statement above, a model

“Software Development Life Cycle Testing Model” is

proposed in which all types of testing techniques related to

test all phases of SDLC are specified. V model of testing

given by Mr. Perry includes only 5 phases of SDLC. Here

this model is extended to include more phases of SDLC and

select the types of testing technique that can be applied in

each phase.

1. Apply Testing on all Phases of SDLC

It has always been a big question when to start testing.

Experts suggest that every step taken in the development of

the system must be tested thoroughly in a formal manner. It

means that testing must be done for requirements gathering,

designing, coding, and even for testing phase. Testing of

testing efforts may seem to be unusual and surprising but

it is an important effort because one needs to be sure about

the testing efforts to be able to rely on its reports. A good

testing life cycle begins during the requirements elicitation

phase of software development, and concludes when the

product is ready to install or ship, following a successful

system test. Fig given below shows that testing applied on all

the phases (Requirement gathering, Designing, Coding,

Testing, Implementation and Maintenance) of SDLC, not a

particular stage. The study of various software development

process models reveal that in almost all these models,

software testing is included as one phase, but testing is

required at each phase and not at a particular stage. In this

SDLC testing model we applied the testing at all the phases

of SDLC. By categorizing which type of testing technique

to be applied at which phase of software development life

cycle will help us plan for testing in that phase efficiently

and to take full advantage of all the types of testing

techniques to improve quality in that phase and consequently

the overall quality of the software project. Well-defined

traceable and controllable processes are required for

enhancing the quality of the software products and gaining

optimum benefits from applied effort. Software process is a

stepwise sequence of activities carried with the focus of

producing quality software in an economic manner it will be

possible when we applied testing at all the phases of software

development life cycle. Software testing is recommended to

be started as early as possible in the earliest phases of the

SDLC, most preferably in the requirement analysis phase

itself and should be performed by skilled testers only and

not by developers. Software development life cycle (SDLC)

processes involve activities of software requirements,

analysis, requirement specification, design, coding, testing,

delivery, and maintenance. The testing phase can be used in

all of these life cycle phases as an umbrella activity.

Fig. (d) Applying testing on all phases of SDLC

International Journal of Soft Computing and Engineering (IJSCE)

ISSN: 2231-2307, Volume-2, Issue-3, July 2012

255

2. Identifying Testing Techniques according to Phase of SDLC We identifying that which type of testing technique can be applied to which phase of SDLC. Fig (e) shows the phases of SDLC

and according to testing technique.

Fig (e) : SDLC Testing Model

3. Application of Testing to Measurement of Quality

Attributes

Different quality attributes need different types of testing

to measure software quality. Various types of testing

according to the quality feature it applies to in the table 6.3.

In given table we identified that for a particular software

quality feature which type of software testing technique can

be applied:

A Research study on Importance of Testing and Quality Assurance in Software Development Life Cycle (SDLC)

Models

256

Table 1: Testing Technique According to Quality Features

Quality

Attribute

Testing

Types

Performance Performance testing

Compatibility Compatibility testing

Reliability Stress testing,

Robustness testing, load testing

Vulnerability Penetrati

on

testing

Consistency Database testing, Table testing

Correctness Database testing, Table testing

Portability

Portabilit

y Testing

Recovery

Recove

ry

testing

Completeness

Boundary/Statement/Loo

p/Condition/Path

coverage testing

V. CONCLUSION & FUTURE WORK

Software testing is the activity that executes software with

an intention of finding errors in it. Testing should be

performed at different levels, including module level testing,

unit level testing, interface testing and system level testing.

Testing is done both at developer end and customer end and

it is performed by testers as well as the customer before

delivery of the product but it can ensure a fair level of

confidence in the predictable behaviour of the product in the

provided conditions.

Quality is the main focus of any software engineering

project. Without measuring, we cannot be sure of the level

of quality in software. So the methods of measuring the

quality are software testing techniques. This thesis report

relates various types of testing technique that we can apply

in measuring various quality attributes. Also which testing

are related to various phase of SDLC. General SDLC

processes are applied to different type of projects under

different conditions and requirements. There are various

type of SDLC model (Waterfall Model, RAD Mode,

Iterative Model, Proto Type Model, Spiral Model,

V-Model, etc). But in all these models, testing is applied

after a particular stage and not in all the phases. In this thesis

report, it is concluded that testing should be applied in all the

phases of SDLC and not at a particular stage. Which type

of testing technique can be applied to which type of SDLC

phase is also summarized.

Future work for this area will be to take more new coming

testing techniques and relating these to the phases of SDLC.

This will help taking the maximum advantage of that testing

technique. And this will be helpful to conclude that.

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International Journal of Soft Computing and Engineering (IJSCE)

ISSN: 2231-2307, Volume-2, Issue-3, July 2012

257

Maneela Tuteja, M-Tech (Computer Science Engineering)

from Amity School of Engineering &

Technology, Amity Unicersity Noida,

B-Tech (Information Technology) from

Kurukshetra University.

Having more than 5 years of professional

experience in IT, Services & Education.