Lect5 6a Test Debug

8/10/2019 Lect5 6a Test Debug

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Software Engineering

2013

Lecture 5 & 6:Unit testing & debugging


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2013 FIT330 Software Engineering 2

Outline

What is testing?

Test (stand-alone) procedures:

Blac bo! "s #hite bo! testing

$e"elop and run tests using %Unit

$eensi"e progra''ing

$ebugging


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What is testing?

or' o progra' "alidation alidation 'eans to "alidate our belie that a

progra' unctions correctl*:

i+e+ satisies its speciication in practice, #e can best increase our conidence

Testing to use real data to test a progra' to'eet its speciication

1


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Testing 'ethod

Test incrementally

Three techni.ues:

unit testing:test each 'odule in isolation

integration testing: test a group o 'odules regression testing: re-run tests ater 'odiications

T#o basic steps:

generate test cases de"elop & run tests


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Test case

/!hausti"e testing is i'practical 0oal: ind a s'all, representati"e set o test

cases

Test case is a set o input data "alues o agi"en test unit

Belie: succeeds #ith T1s 2 succeeds #ith allinput


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Test case

int

?

Test cases someMethod(int x, int[] a)

int[]

3nput do'ains


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Test stand-alone procedures

0enerate test cases: blac-bo! "s+ #hite-bo!

$e"elop and run test:

use %Unit

2



0enerate test cases

Ob4ecti"e: ind approximationso the inputdo'ains

ppro!i'ation based on representati"e testdata sets (T$s)

T#o basic steps:

0enerate T$s

1o'bine T$s to or' test cases

2a



0enerate T$s

intGenerate TDSs

x1

x2

int[]

a1

a2

a3

a4

a5

someMethod(int x, int[] a)

TDS



1o'bine T$s

intGenerate TDSs

Combine TDSs

x1

x2

int[]

a1

a2

a3

a4

a5

...

someMethod(int x, int[] a)



Test cases

intGenerate TDSs

Combine TDSs

x1

x2

int[]

a1

a2

a3

a4

a5

...

Test cases someMethod(int x, int[] a)



0enerate T$s

T$ is a sub-set o "alues o an input do'ain

One input do'ain 'a* contain se"eral T$s

teps to generate T$s:

identi* the input ranges

deine a T$ per range

using representati"e data "alues

x1

x2



Techni.ues

T#o techni.ues: blac-bo! testing (BBT)

glass-bo! (a++a #hite-bo!) testing (0BT)

BBT uses progra' speciication 0BT uses progra' te!t



Blac bo! testing

How do we test this method ?

/*** @effects* if a is null* tho!s "ull#ointe$x%e&tion* else if x is in a

* etuns i su%h that a[i] ' x* else* tho!s "otound$x%e&tion*/publicstaticintsea%h(int[] a, intx)

throws"ull#ointe$x%e&tion, "otound$x%e&tion



Other e!a'ples: st

/*** @requires x >' ++ .1 < e&silon < .1* @effects etun n su%h that* xe&silon < n-2


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BBT: input range criteria

re.uires: constraint e!pressions eects:

output conditions

e!ceptional conditions

1onsider relationships bet#een inputs ineects

Written using se'i-inor'al set notation

nu'ber range notation


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sea%h

/*** @effects* if a is null* tho!s "ull#ointe$x%e&tion* else if x is in a

* etuns i su%h that a[i] ' x* else* tho!s "otound$x%e&tion*/publicstaticintsea%h(int[] a, intx)

7anges: a: 8null9, 8;9 < 8x

1,...,x

n; = x

iare integers9

x: 8= * in a9 < 8= not in a9


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st

/*** @requires x >' ++ .1 < e&silon < .1

* @effects etunn su%h that

* xe&silon < n-2


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is#ime

/*** @effects* if & is a &ime* etuns tue* else

* etuns false*/publicstaticbooleanis#ime(int&)

7anges:

pri'es: 8A,,C,5,+++9 non-pri'es: 8D,6,E,F,+++9


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BBT: T$ or'ation criteria

@or each range use: data t*pe (incl+ arra*)

t*pical and at*pical data o the t*pe

0tindata t*pe: treated as an arra*-t*pe

Other t*pes (later):

iterator

data abstraction t*pe hierarch*


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T*pical "s+ t*pical data

u'eric data t*pe: t*pical: a e# nu'bers in the range

at*pical: s'allest and largest "alues o the range

rra* data t*pe: t*pical: arra*s containing a e# ele'ents

at*pical:

null, e'pt*, one-ele'ent arra* arra*s containing no#n "alues at speciic indices


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T$ e!a'ples: sea%h

7anges: a: 8null9, 8;9 < 8x

1,...,x

n; = x

iare integers9

x: 8= * in a9 < 8= not in a9

T$(s): a: 8null, ;, A;, C,A;, C,A,D;, C,5,A,D;9

x: 8A,9


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st

7anges: x: >,>>>A, +>>A)

T$(s): x: 8>, >+>>A, >+>A, >+>F, >+5,

A, , A>, A>>, ADGDEC6>>9

e&silon: 8+>>>>, +>>>A, +>>>F9

y?


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is#ime

7anges: pri'es: 8,C,5,+++9

non-pri'es: 8D,6,E,F,+++9

T$(s): pri'es: 8,C,5,CA,655CG9

non-pri'es: 8D,C,655CE9 y?


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BBT pros & cons

d"antages: ease T1 generation

robust against i'ple'entation changes

ease result interpretation $isad"antages:

path inco'plete i speciication is la#ed,inco'plete or not obser"ed


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0lass bo! testing

staticintmaxfhee(intx,int,int) if(x > ) if(x > ) returnx6 elsereturn6 7 else

if( > ) return6 elsereturn6

77

How do we test this method ?


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0BT: input range criteria

Use the logic paths ound in: conditional

loop

recursion 1riteria:

conditional e!pression

nu'ber o iterations (loop & recursion onl*)


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1onditional

if#(x) // do this

elseif8(x)

// do thatelse

// do somethinelse

7ange(s):

all xs+t H(x)

all xs+t I(x)

all xs+t+ H(x) && I(x)


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/!a'ple: conditional

staticintmaxfhee(intx,int,int) if(x > ) if(x > ) returnx6 elsereturn6 7 else // x


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deter'inistic loop

staticintsomeMethod(intn) for(inti ' 16 i


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recursion

staticintfa%t(intn) if(n < 1)

return16

else if(n '' 1)

return16 else

returnn * fact(n1)6

7

7ange(s) or n: (-3@,A)

8A9

(A,


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0BT: T$ or'ation criteria

$epends on the range: conditional: data t*pe

loopNrecursion: nu'ber o iterations & ter'ination

7easonable nu'bers o iterations: loop: >, A,

recursion: >, A (base), (inducti"e once), C(inducti"e t#ice)

Ter'ination:

ter'ination "alues

include e!ceptional cases


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T$ e!a'ple: conditional

staticintmaxfhee(intx,int,int) if(x > ) if(x > ) returnx6 elsereturn6 7 else // x


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deter'inistic loop

staticintsomeMethod(intn) for(inti ' 16 i


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non-deter'inistic loop

staticintsomeMethod(intx) while(x > ) // do somethin 7

7

7ange(s) or x:

(-3@,>;

A,,A,9 y?


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recursion

staticintfa%t(intn) if(n < 1)

return16

else if(n '' 1)

return16 else

returnn * fact(n1)6

7

7ange(s) or n: (-3@,A)

8A9

(A,


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conditional & loop (A)

staticintsomeMethod(intx) while(x > ) // %he%9s x modulo 1 if(x : 1 '' 5)

break6 x6 77

7ange(s) or x: (-3@,>; 8 * = * A> 9 8 * = * A> 9

T$(s) or !: 8>, 5,A5,A,9 y?


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conditional & loop ()

staticvoidmMethod(intn, intm) for(inti ' 16 i


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conditional & loop (): T$

staticvoidmMethod(intn, intm) for(inti ' 16 i


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0BT pros & cons

d"antages: useul #hen speciication is la#ed, inco'plete or

not obser"ed

aid code anal*sis and debug

$isad"antages:

re.uires no#ledge o the i'ple'entation

not robust against i'ple'entation changes


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$e"elop and run tests

Testing tass are repetitious

@ull* auto'ated testing is diicult

tep A is diicult to auto'ate

speciications are not al#a*s precise

Step 2can be auto'ated (our ocus here)

using %Unit

2b


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0eneral approach

$e"elop test driversto: realise the test cases

auto'ate the e!ecution o tests

Test run run the test dri"er


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Test dri"er

s'all progra' peciied as a data abstraction

na'ing con"ention:xxxTest

Tass include: initialise the T$s and test cases

initialise the e!pected test results

test each unit Use assertionto chec test results

Pa* or' a t*pe hierarch*


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/!a'ple: dri"er or procedure

One dri"er per procedure

Test< s.uare7oot()

SquareRootTest


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/!a'ple: dri"er or data abstraction

One dri"er per class

- tc3nt5et: int;;- tcRA: int;;- tcR: int;;


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3'ple'ent a test dri"er

Use a third-part* pacage na'ed %Unit T#o "ersions:

%Unit C+5: test dri"ers as sub-t*pes

!"nit #$0(%d K A+5): test dri"ers as annotatedprocedures


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ssertion

boolean state'ent "alidated auto'aticall* b*the run-ti'e en"iron'ent

%a"a e*#ord: asset

"ariants: asset$uals, asset;a$uals Usage:

"alidate test results

deensi"e progra''ing (later)


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ssertion e!a'ple

nt0et s ' ... // initialise sassert(s.e&=() '' true)6

assert(s.sie() '' 2) ?in@alid sie ?s.sie()6

assertthat s.e&=is tre

ot%erwisethro#s an ;ssetion$o

assertthat shas t#o ele'entsot%erwisethro#s ;ssetion$o#ith 'essage in@alid sie ...


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Test dri"er or procedure

a'ed ater the procedure Brie initial speciication onl*:

no @ and rep in"ariant

Test 'ethod: is annotated #ith Aest

thro#s ;ssetion$o

Pa* be para'eterised or each test case


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/!a'ple: 0uaeBootest

%h1.Cunit4.0uaeBootest ote:

arra*s are used to initialise

test cases and results a or loop is used to run each

test case

use static 'ethod;sset.asset$uals

toease assertion test

Test< s.uare7oot()

SquareRootTest


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peciication

/**

* @overview; test di@e fo the "um.st method*/publicclass0uaeBootest /**

* @modifies0stem.out

* @effects* fo ea%h test %ase t% ' < x,e, >* if D"um.st(x)-2 -2D > e* tho!s ;ssetion$o* else

* dis&las "um.st(x) on the std out&ut *

*/ Aest publicvoidsuaeBoot() throws;ssetion$o7

y?


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3'ple'entation

Aest //(timeout ' 5) publicvoidsuaeBoot() throws;ssetion$o //... (%ode omitted) ...

// test %ases

float[] t%$&s ' .2f, .1f, .Ef 76

float[] t%F ' f, .1f, .1f, .Ef, .5f,1f, 2f, 1f, 1f,214G4H3If 76

// test esults float[] esults ' newfloat[t%F.lenth]6

for(inti ' 6 i < t%F.lenth6 i) esults[i] ' (float) Math.sqrt(t%F[i])6

76


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floatx,e,6 for(inti ' 6 i < t%F.lenth6 i) x ' t%F[i]6 ' esults[i]6 for(intC ' 6 C < t%$&s.lenth6 C) 0stem.out.&intln(?>>est %ase ?

((i*t%$&s.lenth)C))6 e ' t%$&s[C]6 floatesult ' "um.sqrt(x, e)6 // assume same delta eo J/! t!o esults assertEquals( * , esult * esult, 2 * e)6

0stem.out.&intf(?st(:f,:f) ' :f ??(ex&e%ted ' :f) :n?, x, e, esult, )6

7 7

7 // end suaeBoot

DE&'


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%h1.Cunit4.0uaeBootest

H i d d i


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Hara'eterised test dri"er

nnotated #ithABunKith(#aameteied.%lass)

7ep deines a test case and e!pected output

constructor to initialise rep #ith suitable args 'ethod to set up the test cases:

annotated #ith A#aametes

stati% return t*pe: Lolle%tion

Test 'ethod operates directl* on the rep

/ lDE&'


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/!a'ple

%h1.Cunit4.0uaeBoot#aameteisedest

$ i i3


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$eensi"e progra''ing

Being e!tra careul #hen progra''ing Three additional VchecsV:

chec rep in"ariant

chec the re.uires constraints e!hausti"e testing o all conditionals

Use assertion to le!ibl* i'ple'ent the checs

3

Th th V h V


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The three VchecsV

1hec rep in"ariant: i'ple'ents repOS

1hec re.uires:

checs input "alues against the pre-condition /!hausti"e testing o conditionals:

co"ers all possible cases (including unspeciied)

/ l


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/!a'ple

0tin s ' Lomm.receive

()6

if(s.euals(?deli@e?))

// %a out the deli@e euest

7 elseif(s.euals(?examine?))

// %a out the examine euest

7

/ l d i


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/!a'ple: deensi"e

0tin s ' Lomm.receive

()6





7 else

// handle eo %ase

7

U ti


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Use assertion

0tin s ' Lomm.receive()6





7 else

// this %an ne@e ha&&en

assertfalse6

7

/ bl Ndi bl ti


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/nableNdisable assertions

ssertions are disabled b* deault To enable (disable) use %PVs option ea(da)

To enable assertions:Ca@a ea M#oam

To disable assertions:

Ca@a da M#oam

$ i i i


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$eensi"e progra''ing issues

7e.uire 'ore progra''ing eortect run-ti'e peror'ance

eed to balance:

code .ualit* costNti'e

peror'ance

$ b i#


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$ebugging

To unco"er and correct bugs (errors) /!a'ine the inter'ediate states

eed test cases that produce the bugs

/icienc* depends on: design

i'ple'entation

docu'entation (e+g+ speciications)

#

$ b i t


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$ebugging steps

@ind bug-producing T1s Locate bugg* code regions

@i! bugg* code regions

7etest progra' (regression testing)

$ebugTestprogra'


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glo#-chart

Debugging

@ind bug-producing TCs

(o)atebugg* code regions

*i+bugg* regions

bugg*?

/nd test

@ind bug producing T1s1


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@ind bug-producing T1s

@or' a h*pothesis consistent #ith the testresult

$esign and run tests that can reute theh*pothesis

7epeat steps A & until a h*pothesis isestablished

0enerate bug-producing T1s ro' the

h*pothesis use t*picalNat*pical "alue rule

1

@lo# chart (A)


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@lo# chart (A)

@or' a h*pothesis

7eute h*pothesis "ia

testing

0enerate bug-producingT1s

reuted?

/!a'ple: (bugg*) "um sea%h


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/!a'ple: (bugg*) "um.sea%h

7un 0ea%hest.sea%h 7un 0ea%hest.Ju0ea%h

What are the bug-producing T1s ?

nother (bugg*) "um sea%h
http://data/projects/hanu/SEG/fall2013/java/src/ch10/junit4/SearchTest.javahttp://data/projects/hanu/SEG/fall2013/java/src/ch10/junit4/SearchTest.javahttp://data/projects/hanu/SEG/fall2013/java/src/ch10/junit4/SearchTest.javahttp://data/projects/hanu/SEG/fall2013/java/src/ch10/junit4/SearchTest.java


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nother (bugg*) "um.sea%h

7un 0ea%hest.Ju0ea%h2 What are the bug-producing T1s ?

Locate bugg* code regions2
http://data/projects/hanu/SEG/fall2013/java/src/ch10/junit4/SearchTest.javahttp://data/projects/hanu/SEG/fall2013/java/src/ch10/junit4/SearchTest.java


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Locate bugg* code regions

Trace the progra' #ith the T1s /!a'ine the inter'ediate results top-do#n

$ata abstraction: chec procedure groups

Hrocedure: chec re.uires 2 eects 1ode region: chec "ariables

ided b* a debugger (e+g+ %a"a debugger)

2

@loat chart ()


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@loat chart ()

Trace the !rogra"with the T#s

E$a"ine inter"e%iate res&ts

co%eregionfon%'

(

)

*se a%e+gger

$ebugDE&'


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$ebug

%h1."um.sea%h Use /clipseVs debugger

$ebug-runs 0ea%hest.Ju0ea%h

What is the bug ?

@i! bugg* code regions3


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@i! bugg* code regions

1areull* anal*se each region 1o''on progra''ing pitalls:

s*ntacticall* correct t*ping errors

re"erse the order o input argu'ents loop one inde! too ar

ail to reinitialise a "ariable

inco'plete code cop*

incorrect use o parentheses in an e!pression

3

$ebug guidelines (A)


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$ebug guidelines (A)

Use a debugger (i one a"ailable)

/nsure the right source code

3'ple'ents sensible to0tin'ethods

bug 'a* occur ar ro' its irst 'aniestation

$eter'ine the progra' assu'ptions

1hec careull* the input (against re.uires)

/li'inate possible code regions

0et help ro' others

Tae a breaX

$ebug guidelines ()


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$ebug guidelines ()

Pae sure the bug 'atches its s*'pto's

Understand #h* the bug occurred #here it is

$eter'ine the i'pacts o code 'odiications

u''ar*


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u''ar*

Testing is a practical 'ethod o "alidating a progra'Vscorrectness

Test cases are generated ro' speciication (BBT)andNor code (0BT)

Test dri"ers are data abstractions i'ple'ented using%Unit

$eensi"e progra''ing in"ol"es inserting checs todetect errors

$ebugging is a 'ethod to unco"er bugs and correct theaected code regions

Iuestions?


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Iuestions?

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