1841f07subdomains2aug23 question u what is the main purpose of software testing?

1841f07subdomains2Aug23

Question

What is the main purpose of software testing?


Testing Basics

Subdomains


Failure Set

The failure set for a fault is the set of points in the program domain that display the fault, that is, cause the output to be different from specified.


Programming task

Who had the smallest failure set?

Who had the largest failure set?

Who had a strange failure set?


Failure Set

-15

-10

-5

0

5

10

15

-15 -10 -5 0 5 10 15

Series1


Subdomain

A subdomain is a set of input points (data points, tests, etc) that are treated identically by the program. That is, they take the same path through the program and the same operations are applied to the values.

Or a set of such subdomains Sometimes called a partition


Different uses in the literature

Much like mine – with mutual exclusion Arbitrary division of the input domain Any definable subset of the input domain

Other?


Example - Payroll Problem

Wages must be greater than zero and less than 100

Hours must be greater than zero and less than 80

Time and a half is paid on hours over 40


Subdomains of Example

I II

0,0

0,100

40,0 80,0


TTYP – how do faults affect the subdomains?

Pay = hours * wage

If hours > 40 then pay = pay + .5*(hours-40)*wage Consider some possible faults in the payroll

program– Can you find faults that affect a whole subdomain?

– Can you find faults that move the boundaries?

– Can you find faults that make bigger changes?


Boundary Testing Example - 2on/1off

V

I II

I-V : (0,100),(40,100),(20,99)

II-V : (41,100),(79,100),(60,99)

I-II : (40,1),(40,99),(41,50)


Triangle Example

cin >> a >> b >> c ;type = “scalene”;if (a == b || a == c || b == c) type= “isosceles”;if (a == b && a == c) type = “equilateral”;if (a >= b+c || b >= a+c || c >= a+b) type=“not a triangle”;if (a <= 0 || b <= 0 || c <= 0) type=“bad input”;cout<< type;


Triangle Domain : a = b plane

a=b

c

a=b=c

a=b=.5c

not a triangle

isosceles

bad inputs

isosceles

bad inputs


Triangle Domain : a = .5b plane

a=.5b

c

a=.5b=.5c

not a triangle

scalene

bad inputs

isosceles

bad inputs

a+b=c

a=b+c

scalene

not a triangle


Control Flow Graph

I: cout

B: type = isoscles

D: type = equilateral

F: type = not a triangle

H: type = bad input

A: type = scalene

C: if

E: if

G: if


TTYP - subdomains

Are paths the best subdomains? Would a functional decomposition be

better? Should we re-define the term subdomain?


For Tuesday, Aug 28

Read ch28 – Shrostrup’s chapter on testing

1841f07subdomains2aug23 question u what is the main purpose of software testing?

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