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BMS Institute of Technology and MgmtDepartment of ISE

Software Testing

Module-1 : Basics of Software Testing

By, Dr.

Manjunath

T. N.

Professor

Dept. of Information Science &

Engg

BMS Institute of Technology, Bengaluru.

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Definition

¾Testing is the process of executing a program

with the intent of finding errors

¾Reasons for testing

¾To discover problems

¾To make judgment about quality or acceptability

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Definition

¾Testing is obviously concerned with

9Errors

9Faults

9Failures

9Incidents

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Definition

‡Errors

9Synonym mistake

9Mistakes while coding-bugs

9Tend to propagate

‡Fault

9Synonym defect

9Result/representation of error

9Modes of expression

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Definition

representationthatisincorrect information.

‡Failure

9Occurswhenfaultexecutes

9Applicabletoonlyfaultsofomission

‡Incident

9Symptomassociatedwithafailure

9Alertsusertooccurrenceofafailure

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Definition

‡Test

the act of exercising software with test caseswith an objective of

9Finding failure

9Demonstrate correct execution

‡Test case

9Has set of inputsand expected outputs.

9Has Identity associated with program behavior

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

A Testing Life Cycle

Requirement

Specs

Design

Coding

Testing

Fault

Resolution

Fault

Isolation

Fault

Classification

Error Fault Fault Fault Error Error incident Fix

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

A Testing Life Cycle

‡Errors-faults-failures propagates in development phases.

‡Testersummariseslifecycleas3phases

9PuttingbugsIN

9Testingphasetfindingbugs

9GettingbugsOUT

9Test planning

9Test case development

9Running test cases

9Evaluating test results.

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Test cases

‡Determine test cases for the item to be tested.

‡Have identity-reason for being

‡InputsPreconditions

Actual inputs

‡ExpectedActual outputs

outputsPost conditions

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Test cases

‡Act of testing entails

9Establishing necessary preconditions

9Providing the test case inputs

9Observing the outputs

9Comparing with the expected outputs

9Ensuring the existence of expected preconditions

‡Records the execution history of test cases

9When & by whom it was run

9Pass/fail results

9Version of software

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Test cases

Typical test case information

Test case ID

Purpose

Preconditions

Inputs

Expected outputs

Post conditions

Execution History

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Insight from Venn diagram

‡Two views

9Structural view -what it is

9Behavioral view -what it does ttesting

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Relationship tprogram behaviors

Program Behaviors

Specified

(expected)

Behavior

Programmed

(observed)

BehaviorFault

Of

Omission

Fault Of

Commission

Correct portion

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Relationship tTesting wrt Behavior

Program Behaviors

Specified

(expected)

Behavior

Programmed

(observed)

Behavior

Test Cases

(Verified behavior) 87
56
1 43
2

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

}všY

‡2, 5

±Specified behavior that are not tested

‡1, 4

±Specified behavior that are tested

‡2, 6

±Programmed behavior that are not tested

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

}všY

‡1, 3

±Programmed behavior that are tested

‡3, 7

±Test cases corresponding to unspecified behavior

‡4, 7

±Test cases corresponding to un-programmed

behaviors

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Inferences

‡If there are specified behaviors for which

there are no test cases, the testing is incomplete

‡If there are test cases that correspond to

unspecified behaviors

±Either such test cases are unwarranted

±Specification is deficient

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Test methodologies

‡Functional (Black box) testing

‡Structural (White box) testing

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Functional Testing/Black box

testing‡Program-a function that maps values from its input domain to values in its output range

‡Content/implementation is not known

‡Function is understood completely in terms of its inputs & outputs ‡For test case identification only specification of the software is used

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Advantages & Disadvantages of

Functional Testing

‡Advantages

9Independent of software implementation

9Test case development can occur in parallel

‡Disadvantage

9Redundancy among test cases.

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Functional Test cases

SpecifiedProgrammed

Test Cases Functional methods are based on the specified behaviors only

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Structural /white box /clear box

testing ‡Implementation is known and used to identify test cases

‡Concept of linear graph theory is required to

understand ‡Test coverage metrics tprovides way to state the extent to which the software item can be tested.

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Structural Test cases

SpecifiedProgrammed

Test Cases Structural methods are based on the programmed behaviors only

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Functional verses structural

‡Redundancy and gaps tproblems of functional testing ‡Functional test cases executed in combination with structural test coverage methods both problems can be recognized and solved. functionalStructural

Program Behaviors

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Errors and fault taxonomies

‡Process-how we do something

‡Product-end result of a process

‡Software quality assurance

9tries to improve product by improving process

9Concerned with reducing errors in development

phases

9Testing concerned with discovering faults in a

product-product oriented.

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Classification of faults

‡Based on Anomaly occurrence

9One time only

9Intermittent

9Recurring/repeatable

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Based on severity

ModerateMisleading or redundant information

DisturbingSome transactions not processed

SeriousLose a transaction

Very seriousIncorrecttransaction execution

IntolerableDatabase corruption

CatastrophicSystem shutdown

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

9Input / output faults

¾correct i/p not accepted

¾wrong format

¾wrong results

9Logic faults

¾missing condition

¾missing cases

¾Incorrect operand/operation

9Computational faults

¾incorrect algorithms

¾missing computations

¾Parenthesis error

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

9Interface faults

¾I/o timing

¾Incorrect i/p handling

¾Call to wrong procedure

9Data faults

¾Incorrect initialisation

¾Incorrect storage/access

¾Wrong flag/index value

¾Incorrect type

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Levels of testing

coding

Preliminary

design

Integration

testing

Detailed

design Unit testing

Requirement

specification

System

testing"""""""""""

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

Generalized pseudo code

‡WOE}À]^language neutral_ÁÇ

Program component

‡Levels of constructs

Unit component

traditional object oriented components components

Procedure & functions Class & object

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

The Triangle Problem

Problem statement

Simple version: The triangle program accepts three integers, a, b, and c, as input. These are taken to be sides of a triangle. The output of the program is the type of triangle determined by the three sides: Equilateral

Isosceles

Scalene

Not A Triangle.

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

The Triangle Problem

Improved version:^^]u‰oÀOE]}v_‰oµššOE definition of inputs: The integers a, b, and c must satisfy the following conditions:

9íXíGGîìì

9îXíGGîìì

9ïXíGGîìì

9c4. a < b + c

9c5. b < a + c

9c6. c < a + b

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

The Triangle Problem

Final Version: ^/u‰OE}ÀÀOE]}v_‰oµššOE definition of outputs:

9If an input value fails any of conditions c1, c2, or c3, the program

notes this with an output message ^soµ}(]v}š]všZOEvP }(‰OEu]ššÀoµX_ for example, If values of a, b, and c satisfy conditions c1, c2, and c3, one of four mutually exclusive outputs is given:

9If all three sides are equal, the program output is Equilateral.

9If exactly one pair of sides is equal, the program output is Isosceles.

9If no pair of sides is equal, the program output is Scalene.

9If any of conditions c4, c5, and c6 is not met, the program output is Not

a Triangle.

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

The Triangle Problem

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

BMS Institute of Technology and MgmtDepartment of ISE BMS Institute of Technology and MgmtDepartment of ISE BMS Institute of Technology and MgmtDepartment of ISE

BMS Institute of Technology and MgmtDepartment of ISEDepartment of ISEBMS Institute of Technology and Mgmt

The NextDate function

‡NextDate is a function of three variables:

9month

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