conventional method (muhammad muchtar aham_108091000071)

8/7/2019 Conventional Method (Muhammad Muchtar Aham_108091000071)

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These courseware materials are to be used in conjunction with Software Engineering: A Practitioners Approach, 5/e and areprovided with permission by R.S. Pressman & Associates, Inc., copyright 1996, 2001

Supplementary Slides for Supplementary Slides for Software Engineering:Software Engineering:A Practitioner's Approach, 5/eA Practitioner's Approach, 5/e

copyright 1996, 2001R.S. Pressman & Associates, Inc.

For University Use OnlyMay be reproduced ONLY for student use at the university level

when used in conjunction with Software Engineering: A Practitioner's Approach.

Any other reproduction or use is expressly prohibited.This presentation, slides, or hardcopy may NOT be used for

short courses, industry seminars, or consulting purposes.


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D esign Concepts and PrinciplesD esign Concepts and Principles


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Analysis to D esignAnalysis to D esign

En t i ty-

elat io nsh ipDiagra

Data F lo Diagra

t a t e -Trans i t ionD i a g r a

Data Dic t ion ary

r o c e s s

pec i f i ca t ion (

EC )

Co ntro l

p ecifi cation (C S P E C )

D a t a b j ec t Desc r ip t ion

THE

L

SIS DEL

p r o c e d u r a ldes ign

in ter facedes ign

a rch i t ec tu ra ldes ign

data

des ign

THE DESIG DEL


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W here D o W e Begin?W here D o W e Begin?

Spec

PrototypePrototype

esign

esign

modeling


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D esign PrinciplesD esign PrinciplesThe design process should not suffer from tunnel vision.The design process should not suffer from tunnel vision.The design should be traceable to the analysis model.The design should be traceable to the analysis model.The design should not reinvent the wheel.The design should not reinvent the wheel.The design should minimize the intellectual distance [DAV9 5] between the softwareThe design should minimize the intellectual distance [DAV9 5] between the softwareand the problem as it exists in the real world.and the problem as it exists in the real world.The design should exhibit uniformity and integration.The design should exhibit uniformity and integration.

The design should be structured to accommodate change.The design should be structured to accommodate change.The design should be structured to degrade gently, even when aberrant data, events,The design should be structured to degrade gently, even when aberrant data, events,or operating conditions are encountered.or operating conditions are encountered.Design is not coding, coding is not design.Design is not coding, coding is not design.The design should be assessed for quality as it is being created, not after the fact.The design should be assessed for quality as it is being created, not after the fact.The design should be reviewed to minimize conceptual (semantic) errors.The design should be reviewed to minimize conceptual (semantic) errors.

From

avis [

AV95]


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F undamental ConceptsF undamental Conceptsabstractionabstraction data, procedure, controldata, procedure, controlrefinementrefinement elaboration of detail for all abstractionselaboration of detail for all abstractionsmodularitymodularity compartmentalization of data andcompartmentalization of data andfunctionfunctionarchitecturearchitecture overall structure of the softwareoverall structure of the software

Structural propertiesStructural propertiesExtraExtra- -structural propertiesstructural propertiesStyles and patternsStyles and patterns

procedureprocedure the algorithms that achieve functionthe algorithms that achieve functionhidinghiding controlled interfacescontrolled interfaces


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D ata AbstractionD ata Abstractiondoor

implemented as a data structure

manufacturer model number type

swing directioninsertslights

typenumber

weightopening mechanism


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Procedural AbstractionProcedural Abstraction

open

implemented with a "knowledge" of theobject that is associated with enter

details of enter algorithm


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Stepwise RefinementStepwise Refinementopen

walk to door;reach for knob;

open door;

walk through;close door.

repeat until door opensturn knob clockwise;if knob doesn't turn, then

take key out;find correct key;insert in lock;

endif pull/push door move out of way;end repeat


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M odular D esignM odular D esigneasier t ild, easier t ange, easier t f ix ...


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M odularity: TradeM odularity: Trade- -offsoffsWhat i the "r i ht" numb e r of modu l es What i s the " r i ht" numb e r of modu l es for a spe ci f i c s of twa r e d es i ? for a spe ci f i c s of twa r e d es i ?

o pt i m a l numb e r o pt i m a l numb e r of modu l es of modu l es

co st

of c

o st

of s of twa r e s of twa r e

n umb e r of modu l es n umb e r of modu l es

modu l e modu l e i nteg r at i o n i nteg r at i o n

co st co st

modu l e d e ve l o p m ent co st modu l e d e ve l o p m ent co st


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Sizing M odules: Two ViewsSizing M odules: Two Views

MODULE

What'sinside??

How bigis it??


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Functional Independence

Functional Independence

COHESION - the degree to which amodule performs one and only onefunction.COUPLING - the degree to which amodule is "connected" to other modules in the system.


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Information HidingInformation Hiding

modulemodulecontrolledcontrolledinterfaceinterface

"secret""secret"

algorithm algorithm data structure data structure details of external interface details of external interface resource allocation policy resource allocation policy

clientsclients

a specific design decisiona specific design decision


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W hy Information Hiding?W hy Information Hiding?reduces the likelihood of side effectsreduces the likelihood of side effectslimits the global impact of local designlimits the global impact of local designdecisionsdecisions

emphasizes communication throughemphasizes communication throughcontrolled interfacescontrolled interfacesdiscourages the use of global datadiscourages the use of global dataleads to encapsulationleads to encapsulation an attribute of an attribute of

high quality designhigh quality designresults in higher quality softwareresults in higher quality software


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Architectural D esignArchitectural D esign


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W hy Architecture?W hy Architecture?

The architecture is not the operational software. Rather, it is aThe architecture is not the operational software. Rather, it is arepresentation that enables a software engineer to: representation that enables a software engineer to:

(1) analyze the effectiveness of the design in meeting its stated(1) analyze the effectiveness of the design in meeting its statedrequirements,requirements,

(2) consider architectural alternatives at a stage when making design(2) consider architectural alternatives at a stage when making designchanges is still relatively easy, andchanges is still relatively easy, and

(3) reduce the risks associated with the construction of the software.(3) reduce the risks associated with the construction of the software.


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D ata D esignD ata D esign

refine data objects and develop a set of datarefine data objects and develop a set of dataabstractionsabstractionsimplement data object attributes as one or implement data object attributes as one or

more data structuresmore data structuresreview data structures to ensure thatreview data structures to ensure thatappropriate relationships have beenappropriate relationships have beenestablishedestablishedsimplify data structures as requiredsimplify data structures as required


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D ata D esignD ata D esign Component LevelComponent Level1. The systematic analysis principles applied to function and behavior should alsobe applied to data.2. All data structures and the operations to be performed on each should beidentified.3. A data dictionary should be established and used to define both data andprogram design.4 . Low level data design decisions should be deferred until late in the designprocess.5 . The representation of data structure should be known only to those modulesthat must make direct use of the data contained within the structure.6. A library of useful data structures and the operations that may be applied tothem should be developed.7. A software design and programming language should support the specificationand realization of abstract data types.


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Architectural StylesArchitectural Styles

D ataD ata--centered architecturescentered architecturesD ata flow architecturesD ata flow architecturesCall and return architecturesCall and return architectures

ObjectObject- -oriented architecturesoriented architecturesLayered architecturesLayered architectures

Each style describes a system category that encompasses: (1) a set of components(e.g., a database, computational modules) that perform a function required by asystem, (2) a set of connectors that enable communication, coordination andcooperation among components, (3) constraints that define how components can beintegrated to form the system, and (4) semantic modelsthat enable a designer tounderstand the overall properties of a system by analyzing the known properties of itsconstituent parts.


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D ataD ata--Centered ArchitectureCentered Architecture


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D ata F low ArchitectureD ata F low Architecture


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Call and Return ArchitectureCall and Return Architecture


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Layered ArchitectureLayered Architecture


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Analyzing Architectural D esignAnalyzing Architectural D esign1. Collect scenarios.1. Collect scenarios.2. E licit requirements, constraints, and environment description.2. E licit requirements, constraints, and environment description.3. escribe the architectural styles/patterns that have been chosen to address3. escribe the architectural styles/patterns that have been chosen to addressthe scenarios and requirements: the scenarios and requirements:

module view module view process view process view data flow view data flow view

4 . Evaluate quality attributes by considered each attribute in isolation.4 . Evaluate quality attributes by considered each attribute in isolation.5 . Identify the sensitivity of quality attributes to various architectural attributes for 5 . Identify the sensitivity of quality attributes to various architectural attributes for a specific architectural style.a specific architectural style.6. Critique candidate architectures (developed in step3) using the sensitivity6. Critique candidate architectures (developed in step3) using the sensitivity

analysis conducted in step5.analysis conducted in step

5.


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An Architectural D esign M ethodAn Architectural D esign M ethod

"four bedrooms, three baths,lots of glass ..."

customer requi remen ts

archi tectural desi gn


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D eriving ProgramD eriving Program

ArchitectureArchitecture

ProgramProgramArchitectureArchitecture


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Partitioning the ArchitecturePartitioning the Architecture

horizontal and vertical partitioninghorizontal and vertical partitioningare requiredare required


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Horizontal PartitioningHorizontal Partitioning

define separate branches of the moduledefine separate branches of the modulehierarchy for each major functionhierarchy for each major functionuse control modules to coordinateuse control modules to coordinatecommunication between functionscommunication between functions

function 1function 1 function 3function 3

function 2function 2


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Vertical Partitioning:Vertical Partitioning:F

actoringF

actoringdesign so that decision making and workdesign so that decision making and workare stratifiedare stratified

decision making modules should residedecision making modules should resideat the top of the architectureat the top of the architecture

workersworkers

decisiondecision- -makersmakers


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W hy Partitioned Architecture?W hy Partitioned Architecture?

results in software that is easier to testresults in software that is easier to testleads to software that is easier to maintainleads to software that is easier to maintain

results in propagation of fewer sideresults in propagation of fewer sideeffectseffectsresults in software that is easier to extendresults in software that is easier to extend


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Structured D esignStructured D esign

objective:objective: to derive a programto derive a programarchitecture that is partitionedarchitecture that is partitionedapproach:approach:

the DFD is mapped into a program architecturethe DFD is mapped into a program architecturethe PSPEC and ST D are used to indicate thethe PSPEC and ST D are used to indicate thecontent of each modulecontent of each module

notation:notation: structure chartstructure chart


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F low CharacteristicsF low Characteristics

Transform flow

Transactionflow


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General

Mapping Approach

General

Mapping Approachisolate incoming and outgoing flowisolate incoming and outgoing flow

boundaries; for transaction flows, isolateboundaries; for transaction flows, isolatethe transaction center the transaction center

working from the boundary outward, mapworking from the boundary outward, mapF transforms into corresponding modulesF transforms into corresponding modules

add control modules as requiredadd control modules as required

refine the resultant program structurerefine the resultant program structureusing effective modularity conceptsusing effective modularity concepts


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Transform M appingTransform M apping

data flo odel

"Transfor " apping

ab

c

d ef

g h

ij

x1

x2 x3 x4

b c

a

d e f g i

h j


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F actoringF actoring

typical "worker" modules

typical "decisionmaking" modules

direction of increasingdecision making


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First Level

Factoring

First Level

Factoring

mainprogramcontroller

inputcontroller

processingcontroller

outputcontroller


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Second Level M appingSecond Level M apping

D

BA

A

B

Dm apping from the

flo boundary out ard

main

control


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Transaction F lowTransaction F low

T

incoming flow

action path


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Transaction ExampleTransaction Example

operator commands

processoperator commands

fixture setting

report

robot control

fixtureservos

displayscreen

robotcontrolsoftware

in reality, other commandswould also be shown

assemblyrecord


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Refining the Analysis M odelRefining the Analysis M odelwrite anEnglish language processing narrativewrite anEnglish language processing narrativefor the level 01 flow modelfor the level 01 flow model

apply noun/verb parse to isolate processes, dataapply noun/verb parse to isolate processes, dataitems, store and entitiesitems, store and entities

develop level 02 and 03 flow modelsdevelop level 02 and 03 flow models

create corresponding data dictionary entriescreate corresponding data dictionary entries

refine flow models as appropriaterefine flow models as appropriate

... now, we're ready to begin design! ... now, we're ready to begin design!

1.1.

2.2.

3.3.

4 .4 .

5 .5 .


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D eriving Level 1D eriving Level 1P ro cess i ng na rr at iv e for " p ro cess o pe r at or comm an d s"

P ro cess o pe r at or comm an d s of t wa r e r ea d s o pe r at or comm an d s from t he ce llo pe r at or . An e rror m essage i s d i sp la ye d for i n v a li d comm an d s .The comm an d t ype i s d ete rm i ne d for v a li d comm an d s an d app ro p r i ate a ct i o n i s ta ken . When f i xt ur e comm an d s a r e en co unte r e d , f i xt ur e stat us i s ana lyze d an d a f i xt ur e sett i ng i s o utp ut t o t he f i xt ur e se r v o s .When a r ep or t i s se le cte d , t he asse m blyr e cord f i le i s r ea d an d a r ep or t i s gene r ate d an d d i sp la ye d o n t he o pe r at or d i sp la y s cr een .

When ro bo t co nt ro l s wi t ches a r e se le cte d , co nt ro l v a lues a r e sent t o t he ro bo t co nt ro l s yste m .

P ro cess i ng na rr at iv e for " p ro cess o pe r at or comm an d s"

P ro cess o pe r at or comm an d s of t wa r e r ea d s o pe r at or comm an d s from t he ce ll o pe r at or . An e rror m essage i s d i sp la ye d for i n v a li d comm an d s .The comm an d t ype i s d ete rm i ne d for v a li d comm an d s an d app ro p r i ate a ct i o n i s ta ken . When f i xt ur e comm an d s a r e en co unte r e d , f i xt ur e stat us i s ana lyze d an d a f i xt ur e sett i ng i s o utp ut t o t he f i xt ur e se r v o s .When a r ep or t i s se le cte d , t he asse m blyr e cord f i le i s r ea d an d a r ep or t i s gene r ate d an d d i sp la ye d o n t he o pe r at or d i sp la y s cr een .When ro bo t co nt ro l s wi t ches a r e se le cte d , co nt ro l v a lue s a r e sent t o t he ro bo t co nt ro l s yste m .

n o un -v e r bpa r se


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Level 1 D ata F low D iagramLevel 1 D ata F low D iagram

operator comm ands

readoperator

comm ands

deter m inecomm and

type

analyzefixturestatus

generatereport

sendcontrol

value

fixtureservos

displayscreen

robotcontrolsystem

asse mblyrecord

valid comm and

rror msg

fixture setting

report

robot control

fixture

select report

controlrobot

status


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Level 2 D ata F low D iagramLevel 2 D ata F low D iagram

readcommand

produceerror msg

validatecommand

determine

type

readfixturestatus

determinesetting

formatsetting

readrecord

calculateoutputvalues

formatreport

reportvalues

record

assemblyrecord

command

command invalid command

status

error msg

robot control

sendcontrolvalue

start /stop

combinedstatus

raw setting

fixture setting


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Transaction M apping PrinciplesTransaction M apping Principles

isolate the incoming flow pathisolate the incoming flow path

define each of the action paths by looking for define each of the action paths by looking for the "spokes of the wheel"the "spokes of the wheel"

assess the flow on each action pathassess the flow on each action path

define the dispatch and control structuredefine the dispatch and control structure

map each action path flow individuallymap each action path flow individually


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Transaction M appingTransaction M apping

data fl w del

ab

t

d e f

i

jl

appi

b

a

x1

t

x2

d e f

x3

g h x3.1

i j

x4

l


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Isolate F low PathsIsolate F low Paths

readcommand

produceerror msg

validatecommand

determine

type

readfixturestatus

determinesetting

formatsetting

readrecord

calculateoutputvalues

formatreport

reportvalues

record

assemblyrecord

command

command invalid command

status

error msg

robot control

sendcontrolvalue

start /stop

combinedstatus

raw setting

fixture setting


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M ap the F low M odelM ap the F low M odelprocessoperator

commands

command

inputcontroller

readcommand

validatecommand

produceerror

message

determine

type

fixturestatus

controller

reportgenerationcontroller

sendcontrolvalue

each of the action paths must be expanded further


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Refining the Structure ChartRefining the Structure Chartprocess operator

comm ands

comm and input

controller

read comm and

validate comm and

produce error

message

deter m ine t pe

send controlvalue

read fi ture status

deter m ine se tting

f or m atse tting

read record

calculate outputvalues

f or matrepor t

fi ture status

controller

repor tgeneration controller


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Interface Are D esignedInterface Are D esigned

intermodular interface designintermodular interface designdriven by data flow between modulesdriven by data flow between modules

external interface designexternal interface designdriven by interface between applicationsdriven by interface between applicationsdriven by interface between software and nondriven by interface between software and non- -humanhumanproducers and/or consumers of informationproducers and/or consumers of information

humanhuman- -computer interface designcomputer interface designdriven by the communication between human anddriven by the communication between human andmachinemachine


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U ser Interface D esignU ser Interface D esign


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Interface D esignInterface D esign

Easy to use?Easy to use?Easy to understand?Easy to understand?

Easy to learn?Easy to learn?


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Interface D esignInterface D esign

lack of consistencylack of consistencytoo much memorizationtoo much memorization

no guidance / helpno guidance / helpno context sensitivityno context sensitivitypoor responsepoor responseArcane/unfriendlyArcane/unfriendly

Ty p i ca l es i gn E rror s Ty p i ca l es i gn E rror s


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G olden RulesG olden Rules

Place the user in controlPlace the user in controlReduce the users memory loadReduce the users memory loadM ake the interface consistentM ake the interface consistent


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Place the U ser in ControlPlace the U ser in Control

Define interaction modes in a way that does not force a user into unnecessary or Define interaction modes in a way that does not force a user into unnecessary or undesired actions.undesired actions.

Provide for flexible interaction.Provide for flexible interaction.

Allow user interaction to be interruptible and undoable.Allow user interaction to be interruptible and undoable.

Streamline interaction as skill levels advance and allow the interaction to beStreamline interaction as skill levels advance and allow the interaction to becustomized.customized.

ide technical internals from the casual user.ide technical internals from the casual user.

Design for direct interaction with objects that appear on the screen.Design for direct interaction with objects that appear on the screen.


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Reduce the U sers M emory LoadReduce the U sers M emory Load

Reduce demand on shortReduce demand on short--term memory.term memory.

Establish meaningful defaults.Establish meaningful defaults.

Define shortcuts that are intuitive.Define shortcuts that are intuitive.

The visual layout of the interface should be based on a real worldThe visual layout of the interface should be based on a real worldmetaphor.metaphor.

Disclose information in a progressive fashion.Disclose information in a progressive fashion.


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M ake the Interface ConsistentM ake the Interface Consistent

Allow the user to put the current task into a meaningful context.Allow the user to put the current task into a meaningful context.

Maintain consistency across a family of applications.Maintain consistency across a family of applications.

If past interactive models have created user expectations, do not makeIf past interactive models have created user expectations, do not makechanges unless there is a compelling reason to do so.changes unless there is a compelling reason to do so.


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U ser Interface D esign M odelsU ser Interface D esign M odels

System perceptionSystem perception the users mental imagethe users mental imageof what the interface isof what the interface isU ser modelU ser model a profile of all end users of thea profile of all end users of thesystemsystemSystem imageSystem image the presentation of thethe presentation of thesystem projected by the complete interfacesystem projected by the complete interfaceD esign modelD esign model data, architectural, interfacedata, architectural, interfaceand procedural representations of theand procedural representations of the

softwaresoftware


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U ser Interface D esign ProcessU ser Interface D esign Process


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Task Analysis and M odelingTask Analysis and M odeling

All human tasks required to do the job (of theAll human tasks required to do the job (of theinterface) are defined and classifiedinterface) are defined and classifiedObjects (to be manipulated) and actionsObjects (to be manipulated) and actions(functions applied to objects) are identified(functions applied to objects) are identifiedfor each taskfor each taskTasks are refined iteratively until the job isTasks are refined iteratively until the job iscompletely definedcompletely defined


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Interface D esign ActivitiesInterface D esign Activities1. Establish the goals and intentions for each task.

2. Map each goal/intention to a sequence of specific actions.

3. Specify the action sequence of tasks and subtasks, also called a user scenario, asit will be executed at the interface level.4 . Indicate the state of the system, i.e., what does the interface look like at the timethat a user scenario is performed? 5 . Define control mechanisms, i.e., the objects and actions available to the user toalter the system state.

6. Show how control mechanisms affect the state of the system.

7. Indicate how the user interprets the state of the system from information providedthrough the interface.


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D esign Evaluation CycleD esign Evaluation Cyclepreliminarydesign

buildprototype #1

interface

evaluationis studied by

designer

designmodifications

are made

buildprototype # n

interface

user evaluate'sinterface

Interface designis complete


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ComponentComponent- -Level D esignLevel D esign


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ComponentComponent- -Level D esignLevel D esign

the closest design activity to codingthe closest design activity to codingthe approach:the approach:

review the design description for thereview the design description for thecomponentcomponent

use stepwise refinement to develop algorithmuse stepwise refinement to develop algorithmuse structured programming to implementuse structured programming to implementprocedural logicprocedural logicuse formal methods to prove logicuse formal methods to prove logic


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Stepwise RefinementStepwise Refinement

openopen

walk to door;walk to door;reach for knob;reach for knob;

open door;open door;

walk through;walk through;close door.close door.

repeat until door opensrepeat until door opensturn knob clockwise;turn knob clockwise;if knob doesn't turn, thenif knob doesn't turn, then

take key out;take key out;find correct key;find correct key;insert in lock;insert in lock;

endif endif pull/push door pull/push door move out of way;move out of way;end repeatend repeat


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The ComponentThe Component- -LevelLevelD esign M odelD esign M odel

represents the algorithm at a level of detailrepresents the algorithm at a level of detailthat can be reviewed for qualitythat can be reviewed for qualityoptions:options:

graphical (e.g. flowchart, box diagram)graphical (e.g. flowchart, box diagram)pseudocode (e.g., P D L)pseudocode (e.g., P D L) ... choice of many... choice of manyprogramming languageprogramming languagedecision tabledecision tableconduct walkthrough to assess qualityconduct walkthrough to assess quality


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Structured ProgrammingStructured Programmingfor Procedural D esignfor Procedural D esign

uses a limited set of logical constructs: uses a limited set of logical constructs: sequencesequenceconditionalconditional if if--thenthen--else, selectelse, select--casecase

loop sloop s dodo--while, rep eat untilwhile, rep eat untilleads to more readable, testable codeleads to more readable, testable code

imp ortant for achieving high quality,imp ortant for achieving high quality,but not enoughbut not enough


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A Structured Procedural D esignA Structured Procedural D esign

a

x1

x2b

3x

4

5

c

d

ef

g

x

x

add a condition Z,if true, exit the progra


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Program D esign Language (P D L)Program D esign Language (P D L)

if-then-else

if condition xthen process a;else process b;

endif

PDL

easy to combine with source codemachine readable, no need for graphics input

graphics can be generated from PDL

enables declaration of data as well as procedure

easier to maintain


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W hy D esign Language?W hy D esign Language?can be a derivative of the OL of choicee.g., Ada PDL

machine readable and processable

can be embedded with source code,therefore easier to maintain

can be represented in great detail, if designer and coder are different

easy to review


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Software Testing TechniquesSoftware Testing Techniques


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Software TestingSoftware Testing

Testing is the process of exercising aTesting is the process of exercising aprogram with the specific intent of findingprogram with the specific intent of findingerrors prior to delivery to the end user.errors prior to delivery to the end user.


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TestabilityTestabilityOperabilityOperability it operates cleanlyit operates cleanlyObservabilityObservability the results of each testthe results of each testcase are readily observedcase are readily observedControlabilityControlability the degree to which testingthe degree to which testing

can be automated and optimizedcan be automated and optimizedD ecomposabilityD ecomposability testing can be targetedtesting can be targetedSimplicitySimplicity reduce complex architecturereduce complex architectureand logic to simplify testsand logic to simplify testsStabilityStability few changes are requestedfew changes are requestedduring testingduring testingU nderstandabilityU nderstandability of the designof the design


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W hat Testing ShowsW hat Testing Shows

errorserrors

requirements conformancerequirements conformance

performanceperformance

an indicationan indicationof qualityof quality


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W ho Tests the Software?W ho Tests the Software?

d e v e l o pe r d e v e l o pe r i n d epen d ent teste r i n d epen d ent teste r

Un d e r st an d s t he s yste mUn d e r st an d s t he s yste mbut , will test "gent l y"but , will test "gent l y"

an d , i s dr iv en by "d e liv e r y"an d , i s dr iv en by "d e liv e r y"

Must l e ar n abo ut t he s yste m,Must l e ar n abo ut t he s yste m,but , will atte mpt t o br e ak i t but , will atte mpt t o br e ak i t

an d , i s dr iv en by quali t yan d , i s dr iv en by quali t y


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Exhaustive TestingExhaustive Testing

loop < 20 Xloop < 20 X

There are 10 possible paths! If we execute oneThere are 10 possible paths! If we execute onetest per millisecond, it would take3,170 years totest per millisecond, it would take3,170 years totest this program!! test this program!!

1414


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Selective TestingSelective Testing

loop < 20 Xloop < 20 X

Selected pathSelected path


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Software TestingSoftware Testing

Methods

Strategies

white-boxmethods

black-boxmethods


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Test Case D esignTest Case D esign

"Bugs lurk in corners"Bugs lurk in cornersand congregate atand congregate atboundaries ..."boundaries ..."

Boris Beizer Boris Beizer

OBJECTI VE OBJECTI VE

CRIT ERIACRIT E RIA

CON STRAINT CON STRAINT

to uncover errorsto uncover errors

in a complete manner in a complete manner

with a minimum of effort and timewith a minimum of effort and time


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W hiteW hite--Box TestingBox Testing

... our goal is to ensure that all... our goal is to ensure that all

statements and conditions havestatements and conditions havebeen executed at least once ...been executed at least once ...


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W hy Cover?W hy Cover?

logic errors and incorrect assumptionslogic errors and incorrect assumptionsare inversely proportional to a path'sare inversely proportional to a path'sexecution probabilityexecution probability

we oftenwe often believebelieve that a path is notthat a path is notlikely to be executed; in fact, reality islikely to be executed; in fact, reality isoften counter intuitiveoften counter intuitive

typographical errors are random; it'stypographical errors are random; it'slikely that untested paths will containlikely that untested paths will containsomesome


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Basis Path TestingBasis Path Testing

First, we compute the cyclomaticcomplexity:

number of simple decisions + 1

or

number of enclosed areas + 1

In this case, V( ) = 4


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Cyclomatic ComplexityCyclomatic ComplexityA number of industry studies have indicatedA number of industry studies have indicatedthat the higher V( ), the higher the probabilitythat the higher V( ), the higher the probabilityor errors.or errors.

V( )V( )

modulesmodules

modules in this range aremodules in this range aremore error pronemore error prone


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Basis Path TestingBasis Path Testing

Next, we derive theNext, we derive theindependent paths: independent paths:

Since V( ) = 4 ,Since V( ) = 4 ,there are four pathsthere are four paths

Path 1: 1,2,3,6,7,8Path 1: 1,2,3,6,7,8Path 2: 1,2,3,5 ,7,8Path 2: 1,2,3,5 ,7,8Path 3: 1,2,4 ,7,8Path 3: 1,2,4 ,7,8Path 4 : 1,2,4 ,7,2,4 ,...7,8Path 4 : 1,2,4 ,7,2,4 ,...7,8

Finally, we derive testFinally, we derive testcases to exercise thesecases to exercise thesepaths.paths.

11

22

3344

55 66

77

88


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Basis Path Testing NotesBasis Path Testing Notes

you don't need a flow chart,you don't need a flow chart,but the picture will help whenbut the picture will help whenyou trace program pathsyou trace program paths

count each simple logical test,count each simple logical test,compound tests count as 2 or compound tests count as 2 or moremore

basis path testing should bebasis path testing should be

applied to critical modulesapplied to critical modules


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Loop TestingLoop Testing

NestedNestedLoopsLoops ConcatenatedConcatenated

LoopsLoops UnstructuredUnstructuredLoopsLoops

SimpleSimplelooploop


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Loop Testing: Simple LoopsLoop Testing: Simple Loops

M i n i mum co n d i t i o ns M i n i mum co n d i t i o ns Si m p l e Loo ps Si m p l e Loo ps

1. s ki p t he l oo p ent i r e l y1. s ki p t he l oo p ent i r e l y2. o n l y o ne p ass t hr ou gh t he l oo p 2. o n l y o ne p ass t hr ou gh t he l oo p

3. t wo p asses t hr ou gh t he l oo p 3. t wo p asses t hr ou gh t he l oo p 4 . m p asses t hr ou gh t he l oo p m < n 4 . m p asses t hr ou gh t he l oo p m < n 5 . (n 5 . (n --1), n , an d (n +1) p asses t hr ou gh1), n , an d (n +1) p asses t hr ou ght he l oo p t he l oo p

whe r e n i s t he m axi mum n um be r whe r e n i s t he m axi mum n um be r o f all o wabl e p asses o f all o wabl e p asses


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Loop Testing: Nested LoopsLoop Testing: Nested Loops

Start at the innermost loop. Set all outer loops to their Start at the innermost loop. Set all outer loops to their minimum iteration parameter values.minimum iteration parameter values.Test the min+1, typical, maxTest the min+1, typical, max--1 and max for the1 and max for theinnermost loop, while holding the outer loops at their innermost loop, while holding the outer loops at their minimum values.minimum values.Move out one loop and set it up as in step 2, holding allMove out one loop and set it up as in step 2, holding allother loops at typical values. Continue this step untilother loops at typical values. Continue this step untilthe outermost loop has been tested.the outermost loop has been tested.

If the loops are independent of one another If the loops are independent of one another then treat each as a simple loopthen treat each as a simple loopelse* treat as nested loopselse* treat as nested loopsendif*endif*

for example, the final loop counter value of loop 1 isfor example, the final loop counter value of loop 1 isused to initialize loop 2.used to initialize loop 2.

N ested LoopsN ested Loops

Concatenated LoopsConcatenated Loops


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Equivalence PartitioningEquivalence Partitioning

user user queriesqueries mousemouse

pickspicks

outputoutputformatsformats

promptsprompts

FKFKinputinput datadata


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Sample EquivalenceSample EquivalenceClassesClasses

user supplied commandsuser supplied commandsresponses to system promptsresponses to system promptsfile namesfile namescomputational datacomputational data

physical parametersphysical parametersbounding valuesbounding valuesinitiation valuesinitiation values

output data formattingoutput data formattingresponses to error messagesresponses to error messagesgraphical data (e.g., mouse picks)graphical data (e.g., mouse picks)

data outside bounds of the programdata outside bounds of the programphysically impossible dataphysically impossible dataproper value supplied in wrong placeproper value supplied in wrong place

Valid dataValid data

I nvalid dataI nvalid data


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Boundary Value AnalysisBoundary Value Analysis

user user queriesqueries mousemousepickspicks

outputoutputformatsformats

promptsprompts

FKFKinputinput datadata

outputoutputdomaindomaininput domaininput domain


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Other Black Box TechniquesOther Black Box Techniqueserror guessing methodserror guessing methodsdecision table techniquesdecision table techniques

cause effect graphingcause effect graphing


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Software Testing StrategiesSoftware Testing Strategies


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Testing StrategyTesting Strategy

unit testunit test integrationintegrationtesttest

validationvalidationtesttestsystemsystemtesttest


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U nit TestingU nit Testing

modulemoduleto beto betestedtested

test casestest cases

resultsresults

softwaresoftwareengineer engineer


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U nit TestingU nit Testing

interfaceinterfacelocal data structureslocal data structuresboundary conditionsboundary conditionsindependent pathsindependent pathserror handling pathserror handling paths

modulemoduleto beto betestedtested



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U nit Test EnvironmentU nit Test Environment

ModuleModule

stubstub stubstub

driver driver

R ESULT SR ESULT S

interfaceinterface

local data structureslocal data structures

boundary conditionsboundary conditions

independent pathsindependent paths

error handling pathserror handling paths



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Integration Testing StrategiesIntegration Testing StrategiesOptions:Options:

the big bang approachthe big bang approach an incremental construction strategyan incremental construction strategy


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Top D own IntegrationTop D own Integration

top module is tested withtop module is tested withstubsstubs

stubs are replaced one atstubs are replaced one ata time, "depth first"a time, "depth first"

as new modules are integrated,as new modules are integrated,some subset of tests is resome subset of tests is re--runrun

AA

BB

CC

DD EE

FF


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BottomBottom- -U p IntegrationU p Integration

drivers are replaced one at adrivers are replaced one at atime, "depth first"time, "depth first"

worker modules are grouped intoworker modules are grouped intobuilds and integratedbuilds and integrated

AA

BB

CC

DD EE

FF

cluster cluster


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Sandwich TestingSandwich Testing

Top modules areTop modules aretested with stubstested with stubs

Worker modules are grouped intoWorker modules are grouped intobuilds and integratedbuilds and integrated

AA

BB

CC

DD EE

FF

cluster cluster


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High Order TestingHigh Order Testing

validation testvalidation test

system testsystem test

alpha and beta testalpha and beta test

other specialized testingother specialized testing

D b iD b i


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D ebugging:D ebugging:A D iagnostic ProcessA D iagnostic Process


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The D ebugging ProcessThe D ebugging Process


resultsresults

Debugging

Debugging

suspectedsuspectedcausescauses

identifiedidentifiedcausescauses

correctionscorrections

regressionregressionteststests

new testnew testcasescases


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D ebugging EffortD ebugging Effort

time requiredtime requiredto diagnose theto diagnose thesymptom andsymptom anddetermine thedetermine thecausecause

time requiredtime required

to correct the error to correct the error and conductand conductregression testsregression tests


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Symptoms & CausesSymptoms & Causes

symptomsymptomcausecause

symptom and cause may besymptom and cause may begeographically separatedgeographically separated

symptom may disappear whensymptom may disappear whenanother problem is fixedanother problem is fixed

cause may be due to acause may be due to a

combination of noncombination of non--errorserrorscause may be due to a systemcause may be due to a systemor compiler error or compiler error

cause may be due tocause may be due toassumptions that everyoneassumptions that everyonebelievesbelieves

symptom may be intermittentsymptom may be intermittent


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Consequences of BugsConsequences of Bugs

damagedamage

mildmild annoyingannoying

disturbingdisturbingseriousserious

extremeextremecatastrophiccatastrophic

infectiousinfectious

Bug TypeBug Type

BugC ategories: BugC ategories: functionfunction--related bugs,related bugs,systemsystem--related bugs, data bugs, coding bugs,related bugs, data bugs, coding bugs,design bugs, documentation bugs, standardsdesign bugs, documentation bugs, standardsviolations, etc.violations, etc.


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D ebugging TechniquesD ebugging Techniques

brute force / testingbrute force / testing

backtrackingbacktracking

inductioninduction

deductiondeduction


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D ebugging: F inal ThoughtsD ebugging: F inal Thoughts

Don't run off half Don't run off half--cocked,cocked, thinkthink about theabout thesymptom you're seeing.symptom you're seeing.

Use toolsUse tools (e.g., dynamic debugger ) to gain(e.g., dynamic debugger ) to gainmore insight.more insight.

If at an impasse,If at an impasse, get helpget help from someone else.from someone else.

Be absolutely sure toBe absolutely sure to conduct regression testsconduct regression tests

when you do "fix" the bug.when you do "fix" the bug.

1.1.

2.2.

3.3.

4 .4 .


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Software Quality AssuranceSoftware Quality Assurance


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W hy SQA Activities Pay Off?W hy SQA Activities Pay Off?cost to findcost to find

and fix a defectand fix a defect100100

1010

l og l og

scal escal e

11

Req.Req.Desig nDesig n

codecodetesttest systemsystem

testtestfiel dfiel d

useuse

0.750.75 1.001.001.501.50

3.003.00

10.0010.00

60.0060.00--100.00100.00


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Quality ConceptsQuality Concepts

general objective: reduce the variationgeneral objective: reduce the variationbetween samples ... but how does this applybetween samples ... but how does this applyto software?to software?quality control: a series of inspections,quality control: a series of inspections,reviews, testsreviews, testsquality assurance: analysis, auditing andquality assurance: analysis, auditing andreporting activitiesreporting activitiescost of qualitycost of quality

appraisal costsappraisal costs

failure costsfailure costsexternal failure costsexternal failure costs


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Software Quality AssuranceSoftware Quality Assurance

FormalTechnicalReviews

SQASQA

TestPlanning& ReviewMeasurement

Analysis&

Reporting

ProcessDefinition &Standards


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Reviews & InspectionsReviews & Inspections

... there is no particular reason... there is no particular reason

why your friend and colleaguewhy your friend and colleaguecannot also be your sternest critic.cannot also be your sternest critic.Jerry W einbergJerry W einberg


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W hat Are Reviews?W hat Are Reviews?a meeting conducted by technical people for a meeting conducted by technical people for technical peopletechnical peoplea technical assessment of a work producta technical assessment of a work productcreated during the software engineeringcreated during the software engineeringprocessprocessa software quality assurance mechanisma software quality assurance mechanisma training grounda training ground


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W hat Reviews Are Not!W hat Reviews Are Not!

T he y a r e n o t : T he y a r e n o t :

a pro je ct budget summa r y a pro je ct budget summa r y a sche dulin g a sse ssment a sche dulin g a sse ssment

an o ve r a ll pro gr e ss r e por t an o ve r a ll pro gr e ss r e por t a me chan ism f or r e pr isa l or po lit ica la me chan ism f or r e pr isa l or po lit ica lint r igue!!int r igue!!


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The PlayersThe Players

reviewreviewleader leader

producer producer

recorder recorder reviewer reviewer

st an dards b earer (SQA) st an dards b earer (SQA)

m aint en an cem aint en an ceoracleoracle

us er repus er rep

C d i h R iC d i h R i


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Conducting the ReviewConducting the Reviewbe preparedbe preparedevaluateevaluate

product before the reviewproduct before the reviewreview the product, notreview the product, notthe producer the producer

keep your tone mild, askkeep your tone mild, askquestions instead of questions instead of making accusationsmaking accusations

stick to the review agendastick to the review agenda

raise issues, don't resolve themraise issues, don't resolve them

avoid discussions of styleavoid discussions of stylestick to technicalstick to technical

correctnesscorrectnessschedule reviews as project tasksschedule reviews as project tasks

record and report all review resultsrecord and report all review results

1.1.

2.2.

3.3.

4 .4 .

5 .5 .

6.6.

7.7.

8.8.


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Review Options M atrixReview Options M atrix

trained leader trained leader agenda establishedagenda establishedreviewers prepare in advancereviewers prepare in advanceproducer presents productproducer presents productreader presents productreader presents productrecorder takes notesrecorder takes noteschecklists used to find errorschecklists used to find errorserrors categorized as founderrors categorized as foundissues list createdissues list createdteam must signteam must sign--off on resultoff on result

IPRIPRinformal peer review WTinformal peer review WTWalkthroughWalkthroughININInspection RRRInspection RRRround robin reviewround robin review

IPRIPR WTWT ININ RRRRRR

nonomaybemaybemaybemaybemaybemaybe

nonomaybemaybenononononononono

yesyesyesyesyesyesyesyes

nonoyesyesnonononoyesyesyesyes

yesyesyesyesyesyesnono

yesyesyesyesyesyesyesyesyesyesyesyes

yesyesyesyesyesyesnono

nonoyesyesnonononoyesyesmaybemaybe

**

*


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M etrics D erived from ReviewsM etrics D erived from Reviews

inspection time per page of documentationinspection time per page of documentationinspection time per KLOC or FPinspection time per KLOC or FP

errors uncovered per reviewer hour errors uncovered per reviewer hour errors uncovered per preparation hour errors uncovered per preparation hour errors uncovered per SE task (e.g., design)errors uncovered per SE task (e.g., design)number of minor errors (e.g., typos)number of minor errors (e.g., typos)

number of errors found during preparationnumber of errors found during preparation

number of major errorsnumber of major errors

(e.g., nonconformance to req.) (e.g., nonconformance to req.)

inspection effort per KLOC or FPinspection effort per KLOC or FP


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Statistical SQAStatistical SQA

ProductProduct& Process& Process

measurement

... an understandi ng of h ow to i mp rov e quali ty ...

co ll ect i nf ormati on on all co ll ect i nf ormati on on all def ectsdef ects

f i nd th e causes o f th ef i nd th e causes o f th edef ectsdef ects mo v e to p rovi de f i xes f or mo v e to p rovi de f i xes f or th e p rocessth e p rocess

conventional method (muhammad muchtar aham_108091000071)

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