Test design techniques

Presented to Dr. Ghazy Assassa

Benha University, Shoubra faculty of engineering, Department of computer engineering,

Software Engineering course. March 2013

By : Mohamed Mahmoud El-shenawy

Test Design Techniques

A test design technique basically helps us to select a good set of tests from the total number of all possible tests for a given system.

There are two main categories:1. Static technique2. Dynamic techniquei. Specification-based (black-box, also known as

behavioral techniques)ii. Structure-based (white-box or structural

techniques)iii. Experience- based

Categories of test design techniques?

Static (non-execution)• examination of documentation,

source code listings, etc.

Functional (Black Box)• based on behaviour /

functionality of software

Structural (White Box)• based on structure

of software

Three types of systematic technique

Some test techniquesStaticStatic DynamicDynamic

StructuralStructural

BehaviouralBehavioural

FunctionalFunctionalNon-functionalNon-functional

ReviewsReviews

WalkthroughsWalkthroughs

Desk-checkingDesk-checking

DataFlowDataFlow

SymbolicExecutionSymbolicExecution

Definition-UseDefinition-Use

StatementStatement

Branch/DecisionBranch/Decision

Branch ConditionBranch Condition

Branch ConditionCombinationBranch ConditionCombination

LCSAJLCSAJ

ArcsArcs

EquivalencePartitioningEquivalencePartitioning

BoundaryValue AnalysisBoundaryValue Analysis

Cause-Effect GraphingCause-Effect Graphing

RandomRandom

UsabilityUsability

PerformancePerformance

Static AnalysisStatic AnalysisInspectionInspection

ControlFlowControlFlow

etc.etc.

etc.etc.

etc.etc.

etc.etc.

etc.etc.

State TransitionState Transition

There are four specification-based or black-box technique:

Equivalence partitioningBoundary value analysisDecision tablesState transition testing

Black-box, Specification-based, also known as behavioral testing techniques

divide (partition) the inputs, outputs, etc. into areas which are the same (equivalent)

assumption: if one value works, all will workone from each partition better than all from

one

Equivalence partitioning (EP)

1 100 1010

valid invalidinvalid

Boundary value analysis (BVA)

faults tend to lurk near boundariesgood place to look for faultstest values on both sides of boundaries

1 100 1010

valid invalidinvalid

Example: Loan applicationCustomer Name

Account number

Loan amount requested

Term of loan

Monthly repayment

Term:

Repayment:

Interest rate:

Total paid back:

6 digits, 1stnon-zero£500 to £9000

1 to 30 years

Minimum £10

2-64 chars.

Account number

5 6 7invalid

validinvalid

number of digits:

first character:invalid: zero

valid: non-zero

Conditions ValidPartitions

InvalidPartitions

ValidBoundaries

InvalidBoundaries

Accountnumber

6 digits1st non-zero

< 6 digits> 6 digits1st digit = 0non-digit

100000999999

5 digits7 digits0 digits

If you do boundaries only, you have covered all the partitions as welltechnically correct and may be OK

if everything works correctly!if the test fails, is the whole

partition wrong, or is a boundary in the wrong place - have to test mid-partition anyway

Why do both EP and BVA?

explore combinations of inputs, situations or events,

it is very easy to overlook specific combinations of input

Decision tables provide a systematic way of stating complex business rules, which is useful for developers as well as for testers.

they help testers explore the effects of combinations of different inputs and other software states that must correctly implement business rules.

Decision table

If you are a new customer and you want to open a credit card account then there are three conditions first you will get a 15% discount on all your purchases today, second if you are an existing customer and you hold a loyalty card, you get a 10% discount and third if you have a coupon, you can get 20% off today (but it can’t be used with the ‘new customer’ discount). Discount amounts are added, if applicable.

Credit card example:

A state transition model has four basic parts: The states that the software may occupy

(open/closed or funded/insufficient  funds); The transitions from one state to another (not

all transitions are allowed); The events that cause a transition (closing a

file or withdrawing money); The actions that result from a transition (an

error message or being given your cash).

State transition

Figure 4.2 below, shows an example of entering a Personal Identity Number (PIN) to a bank account.

PIN Example