software testing new

8/8/2019 Software Testing New

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SOFTWARETESTING

Table Of Contents

1. Introduction to Software Testing

2. Building Software Testing Strategy

3. Establishing a Software Testing Methodology

4. Determining Your Software TestingTechniques

Introduction to Software

Testing

Testing Myths

Testing is nothing but Debugging

Testing is not the job of the programmer

Testing is done to prove that software

³works´

Testing is done to prove that software

doesn¶t ³work´

Testing activities start only after the coding iscomplete

Testing is not a creative Task

Testing Realities

Testing is a structured process of uncovering the defects in a system

Testing is an integral part of SDLC

Testing can be started early in the life

The purpose of testing is to have all the

bugs known before release

Introduction

Software testing is a vital part of the software

lifecycle. To understand its role, it is instructive toreview the definition of software testing in theliterature.

Among alternative definitions of testing are the

following:

"..the process of exercising or evaluating a system or system component by manual or automated means to

verify that it satisfies specified requirements or to identify differences between expected and actual results ..."

contd...

"... any activity aimed at evaluating an attribute or capability of a program or system and determining that it meets its required results. Testing is the measurement of software quality ..."

"... the process of executing a program with the

intent of finding errors..."

contd..

-Software testing is defined as 'the executionof a program to find its faults'.

- A successful test is one that finds a defect.

- Besides finding faults, a software can alsobe tested for performance, safety, fault-

tolerance or security.

Why Test?

No matter how well software has beendesigned and coded, it will inevitably still

contain defects

Testing is the process of executing a program

with the intent of finding faults

A ³successful´ test is one that finds errors, not

one that doesn¶t find errors

Testing can ³prove´ the presence of faults(bugs), but can not ³prove´ their absence

What is a Defect?

A defect is a variance from a desired product

attribute. There are two categories of defects:

± variance from product specifications

± variance from customer/user expectation

Defects generally fall into one of the following three

categories: ± Wrong

± Missing

± Extra

Defects versus Failures

While the defect is a flaw in the software system, it

has no impact until it affects the user/customer and

the operational system.

A defect that causes an error in operation or

negatively impacts a user/customer is called a failure.

Software Quality

Subjective ± as it depends on customer satisfaction

Bug free delivered on time

within budget

meets requirements

maintainable

Building a SoftwareTesting Strategy

Computer System Strategic Risks

- A risk is a condition that can result in a loss.

- The development and installation of a computer

system introduces risks into the organization.

- We cannot eliminate risks, but we can mitigate them.- One of the most effective methods to reduce computer

system strategic risk is testing.

Types of strategic risk:

Incorrect results will be produced

Unauthorized transactions will be accepted by the

system.

Continued . . .

Computer file integrity will be lost.

Processing cannot be reconstructed.Continuity of processing will be lost.

Service provided to the user will degrade to an

unacceptable level.

Security of the system will be compromised.

Processing will not comply with organizational

policy or governmental regulation.

Continued . . .

Results of the system will be unreliable.

System will be difficult to use. Programs will be unmaintainable.

System will not be portable to other hardware an

software.

System will not be able to interconnect with othecomputer systems.

Performance level will be unacceptable.

System will be difficult to operate.

Continued . . .

- An effective approach to testing is to identify andevaluate the risks in a computer system.

- Those risks deemed important to reducebecome the areas for testing.

- A decision can be made as to how much risk isacceptable and then a test plan designed toachieve that goal.

Economics of Testing

"Too little testing is a crime - Too muchtesting is a sin."

480 12

1680 0

NORMAL SDLC SDLC TESTING ACCUMULATED ACCUMULATED ACCUMULATED ACCUMULATED

TEST ERRORS/1000 ERRORS/1000 TEST

COST LINES CODE LINES CODE COST

DESIGN 20

ERRORS

CODE 20

ERRORS

TEST 80%ERROR

REQUIREMENTS

20 ERRORS

PRODUCTION

³0³ ERRORS

Structured Approach to Testing

Requirements Design Code

(Build / Construction)

Test Operation &

Maintenance

Traditional software development life cycle

- All too often, testing after coding is the only

verification technique used to determine the adequacy

of the system.

- When testing is constrained to a single phase and

confined to the later stages of development, severe

consequences can develop.

- It is usual to hear of testing consuming 50% of

the development budget.

- All errors are costly, but the later in the life cycle

that the error discovery is made, the more costly

the error.

- An error discovered in the latter parts of the life

cycle must be paid for four different times.

CODING ERRORS

ANALYSIS AND

DESIGN ERRORS64%

Analysis and design errors are the most numerous

- The recommended testing process is presented in

previous diagram as a life cycle chart showing the

verification activities for each phase.

- The success of conducting verification throughout the

development cycle depends upon the existence of

clearly defined and stated products at each development

stage.

- The recommended test process involves testing in

every phase of the life cycle. Life cycle verification

activities table

Structured Approach to TestingLIFE CYCLE PHASE EMPHASIS VERIFICATION ACTIVITIES

Requirements Upon validation to determine that the defined

requirements meet the needs of the

organization.

Determine verification approach

Determine adequacy of

requirements Generate functional test data

Determine consistency of design

with requirements

Design On verification to ensure that the design

accomplish the defined requirements.

Determine adequacy of design

Generate structural and functional

test data

Determine consistency withdesign

Program (build /

construction)

On verification to ensure that the programs

accomplish the defined requirements.

Determine adequacy of

implementation

Generate structural and functional

test data for programs

Test On inspection to determine that the

implemented system meets the systemspecification.

Test application system

Installation On inspection to determine that the

implemented system meets the system

specification.

Place tested system into

production

Maintenance Retesting to determine that the changes work

and that the unchanged portion continuesto work.

Modify and retest

Test Strategy

The objective of testing is to reduce the risksinherent in computer systems.

The strategy must address the risks and presenta process that can reduce those risks.

The system concerns or risks then establish theobjectives for the test process.

The two components of the testing strategy arethe test factors and the test phase.

Test factor:The risk or issue that needs to be addressed as

part of the test strategy. The strategy will select

those factors that need to be addressed in the

testing of a specific application system.

Test phase:

The phase of the systems development life cyclein which testing will occur.

Not all test factors will be applicable to all

software systems.

The development team will need to select and

rank the test factors for the specific software

system being developed. Once selected and

ranked, the strategy for testing will be partially

defined.

The test phase will vary based on the testing

methodology used.

Ex: The test phases in a traditional waterfalllifecycle methodology will be much different from

the phases in a Rapid Application Development

methodology.

Test Factors

CorrectnessFile Integrity

Authorization

Audit Trail

Continuity of processingService levels

Access control

Compliance

ReliabilityEase of use

Test Factors

Continued . . .

Maintainability

Portability

Coupling

Performance

Ease of

Operation

Developing a Test Strategy

A generic test strategy is illustrated in the figurewhich is a test_factor/test_phase matrix. However,

this strategy will need to be customized for any

specific software system.

Four steps must be followed to develop a customizedtest strategy.

Select and rank test factors

Identify the system development phases

Identify the business risks associated with the

system under development

Place risks in the matrix

Test Strategy Matrix

FACTORS

(high to low)

Factor or

RisksTest

Concerns

Testing Methodology

The testing methodolgy we propose

incorporates both testing strategy and testing

tactics. The tactics add the test plans, test

criteria, testing techniques, and testing toolsused in validating and verifying the software

system under development.

Establishing a SoftwareTesting Methodology

Establishing a Software Testing

Methodology

The testing methodology is the means bywhich the test strategy is achieved.

Testers Job.

What Are You Testing For?

Variance from specifications

Variance from what is desired

Testers need to identify both types of

defect.

Why Are Defects Hard to Find?

Not Looking.

Looking, but not seeing.

The four testing tactics of validation,

verification, functional test, and structuraltest, which are the bread and butter of

testing can be separated into two groups:

(1) validation and verification

(2) functional and structural testing

Verification and Validation

Verification :

"Did we build the right system?

Validation :

"Did we build the system right?³

VERIFICATION

EXAMPLE

PERFORMED BY EXPLANATION DELIVERABLE

Requirements reviews Developers, Users The study & discussion

of the computer system reqs to ensure

they meet stated user

needs & are feasible

Reviewed statement of

requirements, ready tobe translated into

system design.

Design Reviews Developers The study & discussion

of the computer

system design toensure it will support

the system

requirements

System design, ready

to be translated into

computer programs,hardware configs,

docs, and training.

Code Walkthroughs Developers An informal analysis of

the program source

code to find defects

and verify codingtechniques.

Computer software

ready for testing or

more detailed

inspections by thedeveloper.

Code Inspections Developers, Subject

Matter Experts

A formal analysis of the

program source code

to find defects as

defined by meeting

computer designs ecifications.

Computer software

ready for testing by the

developer.

Computer SystemVerification Examples

VALIDATION

EXAMPLE

PERFORMED BY EXPLANATION DELIVERABLE

Unit Testing Developers The testing of a single

program, module, or unitof code. Validates that the

unit performs as designed.

Software unit ready for

testing with other systemcomponent, such as other

units, hardware, docs, or

users.

Integrated Testing Developers, Testers The testing of related

programs, modules, or

units of code. Validates

that multiple parts of thesystem interact according

to the system design.

Portions of the system

ready for testing with other

portions of the system.

System Testing Developers, Testers The testing of an entire

computer system. This

kind of testing can include

functional and structural

testing, such as stress

testing. Validates the

system reqs.

A tested computer system,

based on what was

specified to be developed

or purchased.

User Acceptance

Testing

Testers, Users The testing of a computer

system or parts of a

computer system to make

sure it will work in the

system regardless of what

the system requirementsindicate.

A tested computer system,

based on user needs.

Computer SystemValidation Examples

Functional and Structural Testing

What is Functional Testing?

What is Structural Testing?

Functional Testing

Advantages :

- Simulates actual system usage.

- Makes no system structure assumptions.

Disadvantages :

- Potential of missing logical errors in software.

- Possibility of redundant testing.

Structural Testing

Advantages :

- Software¶s structure logic can be tested.

- Areas not covered in functional testing can be

tested.

Disadvantages :

- Doesn¶t ensure that software meets user requirements.

- Its tests may not mimic real-world situations.

Considerations in Developing

Testing Methodologies

Following are considerations to convert the

developed test strategy, into test tactics or test

plan that will be followed in executing the day-to-

day testing.

1. Acquire and study the test strategy

2. Determine the type of development Project.3. Determine the type of software system.

4. Determine the project scope.

Considerations in Developing

Testing Methodologies

Continued . . .

5. Identify the tactical risks.

6. Determine when testing should occur.

7. Build the system test plan.

8. Build the unit test plan.

Determining Your Software TestingTechniques

Determining Your Software

Testing Techniques

Common testing techniques used in evaluatingcomputerized applications are divided into threecategories:

(1) System structural testing techniques

(2) System functional techniques

(3) Unit testing techniques.

We would also see the interrelationship betweenthe test factors and the techniques in order toillustrate the purpose for which each of thedescribed techniques is most valuable.

Testing Concepts

1. Structural Vs functional testing

2. Dynamic Vs static testing3. Manual Vs automatic testing

Structural Vs Functional Testing

Structural Testing

Properties of TEST SET derived from the

program's internal structure.

Functional Testing

Properties of TEST SET derived from a

description of the program's function.

Structural Testing

Structural analysis based test sets tend touncover errors that occur during "coding" of the

program.

Functional Testing

Functional analysis-based test sets tend to

uncover errors that occur in implementingrequirements or design specifications.

Structural Testing

Structural testing ensures sufficient testing of the

implementation of a function.

It is used primarily during the coding phase,

structural analysis should be used in all phases

of the life cycle where the software is

represented formally in some algorithmic,design, or requirements language.

Continued . . .

The intent of structural testing is to assess theimplementation by finding test data that will forcesufficient coverage of the structures present in

the implemented application.

Structural testing evaluates both that all aspectsof the structure have been tested and that the

structure is sound. Determining that all tasksthrough a structure are tested is a difficultprocess and one requiring extensive test data.However, determining if the structure functionsproperly is a test task that is more easily

accomplished.

Functional Testing

Functional testing ensures that the requirements

are properly satisfied by the application system.

The functions are those tasks that the system is

designed to accomplish.

Functional testing is not concerned with howprocessing occurs, but rather, with the results of

processing.

Dynamic Vs Static Testing

TEST METHODS can be classified into Dynamic

and Static techniques.

Dynamic Testing

Dynamic analysis requires that the program be

executed and hence involves the traditional

notion of program testing.

i.e. The program is run on some test cases and

the results of the program's performance are

examined to check whether the program

operated as expected.

Static Testing

Static analysis does not usually involve actual

program execution. Common static analysis

techniques include such tasks as syntax

checking.

Dynamic Testing

Exhaustive Testing:

It is a Dynamic analysis technique.

It is infinite and infeasible.

Static Testing ± Carried out during initial phases

of SDLC

Dynamic Testing ± Carried out during Later

phases of SDLC.

- Find criteria for choosing representative test

cases from the total population of test

conditions.

- Normally a c ombination of stati c and dynami c

tests is used, selecting a reasonable subset of

test conditions to provide a high probability that

the system will perform correctly in an

operational status.

Manual Vs Automated Tests

- Manual techniques are performed by people,

and automated techniques by the computer.

- This classification is made on the basis of

whether the method is a manual one, such as

structured walkthrough or code inspections, or

whether the method is automated.

Manual Vs Automated Tests

- The more automated the developmental

process, the easier it becomes to automate the

test process.

- On the other hand, the greater reliance on

people to analyze, document, and develop

computer system manually, the more it becomes

necessary to test manually.

Testing

SELECT TEST FACTOR

DETERMINE SDLC PHASE

IDENTIFY CRITERIA TO TEST

SELECT TYPE OFTEST

UNIT TEST TECHNIQUE

SELECT TESTMETHOD

SELECT MANUALOR

AUTOMATED

SELECT MANUALOR

AUTOMATED

SELECT MANUALOR

AUTOMATED

SELECT MANUALOR

AUTOMATED

SELECT MANUALOR

AUTOMATED

SELECT MANUALOR

AUTOMATED

SELECT TESTMETHOD

SELECT TECHNIQUE SELECT TECHNIQUE

SYSTEM STRUCTURAL SYSTEM FUNCTIONAL

DYNAMIC DYNAMIC DYNAMISTATIC STATIC STATIC

Testing

Techniques

Selection

Process

Structural System Testing

Techniques

- Structural system testing is designed to verifythat the developed system and programs work.

- The objective is to ensure that the productdesigned is structurally sound and will functioncorrectly.

-It attempts to determine that the technology hasbeen used properly and that when all thecomponent parts are assembled they function asa cohesive unit.

Structural System Testing

Techniques

Continued . . .

- The structural system testing techniques provide

the facility for determining that the implementedconfiguration and its inter -relationship of partsfunctions so that they can perform the intendedtasks.

- The techniques are not designed to ensure thatthe application system is functionally correct, butrather, that it is structurally sound.

TECHNIQUE DESCRIPTION EXAMPLE

STRESS Determine system performs

with expected volumes

Sufficient disk space

allocated

Communication lines

adequate

EXECUTION System achieves desired level

of proficiency

Transaction turnaround time

adequate

Software/hardware use

optimized

RECOVERY System can be returned to anoperational status after a failure

Induce failureEvaluate adequacy of

backup data

OPER ATIONS System can be executed in a

normal operational status

Determine systems can run

using document

JCL adequate

COMPLIANCE System is developed in

accordance with standards and

procedures

Standards followed

Documentation complete

SECURITY System is protected in

accordance with importance to

organization

Access denied

Procedures in place

Functional System Testing

Techniques

- Functional system testing is designed to ensure

that the system requirements and specifications

are achieved.

- The process normally involves creating test

conditions for use in evaluating the correctness

of the application.

REQUIREMENTS System performs as

specified

Prove system requirements

Compliance to policies,

regulations

REGRESSION Verifies that anything

unchanged still performs

correctly

Unchanged system segments

function

Unchanged manual

procedures correct

ERROR HANDLING Errors can be prevented or

detected, & then corrected

Error introduced into test

Errors re-entered

MANUAL SUPPORT The people-computer interaction works

Manual procedures developed

People trained

INTERSYSTEMS Data is correctly passed

from system to system

Intersystem parameters

changed

Intersystem docs updated

CONTROL Controls reduce system risk

to an acceptable level

File reconciliation procedures

Manual controls in place

PARALLEL Old & new system are run &

the results compared to

detect unplanned difference

Old & new system can

reconcile

Operational status of old

system maintained

T hanks- Q A Team

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