Levels of Testing

Chapter 12

Beyond unit testing

LOT–2

Life cycle models

What is a life cycle model of software development?

What is the traditional life cycle model?

LOT–3

V-Model – development & testing

Requirements

DetailedDesign

Moduleimplementation Unit test

Integration test

System test

Acceptancetest

Run

testsW

rite tests

Customer

Developer

Functional

Structural

ArchitecturalDesign

LOT–4

Traditional model

How well do the levels of the traditional Waterfall modelcorrelate with testing?

In what way?

LOT–5

Traditional model – 2

How well do the levels of the traditional Waterfall modelcorrelate with testing?

In what way? Levels correlate with levels of testing

Functional testing is implied

Bottom up testing is implied

LOT–6

Developer – unit testing stage

What is unit testing?

How do we do unit testing?

LOT–7

What is unit testing?

How do we do unit testing?

Testing of individual components

Unit is best understood

Have both functional and structural testing

Developer – unit testing stage – 2

LOT–8

Developer – integration testing stage

What is integration testing?

How do we do integration testing?

LOT–9

What is integration testing?

How do we do integration testing? Testing to expose problems arising from the

combination of components Bottom up

Combine smaller units into larger ones, untilsystem level is reached

Developer – integration testing stage – 2

LOT–10

Developer – system testing stage

What is system testing?

How do we do system testing?

LOT–11

What is system testing?

How do we do system testing?

Testing the complete system prior to delivery

Functional testing

No good structural notation for descriptions

Developer – system testing stage – 2

LOT–12

Acceptance testing stage

What is acceptance testing?

Who does it?

LOT–13

What is acceptance testing?

Who does it?

Testing by clients / users to check that the systemsatisfies requirements

Sometimes called alpha testing

Acceptance testing stage – 2

Basic development methods

What are the three basic methods that can be used todevelop a system?

LOT–14

LOT–15

What are the three basic methods that can be used todevelop a system?

Top down

Bottom up

Big Bang

Basic development methods – 2

LOT–16

Top-down development

How does top-down development work?

LOT–17

Top-down development – 2

How does top-down development work?

Build upper level Test using stubs

Throw away Repeat with next lower level

LOT–18

Bottom-up development

How does bottom-up development work?

LOT–19

Bottom-up development – 2

How does bottom-up development work?

Build lower levels

Test with drivers Throw away Repeat with next higher level

LOT–20

Big bang development

How does big-bang development work?

LOT–21

Big bang development

How does big-bang development work?

Build everything

Then test

No stubs or drivers

LOT–22

Problems with waterfall model

What are the problems with the waterfall model?

LOT–23

Problems with waterfall model – 2

What are the problems with the waterfall model? Too slow Too rigid Too focused on top-down functional development and

bottom-up testing Not the way people work Staffing levels of different types batched at different

times with the levels requiring large resource shiftsfrom low to high and back.

LOT–24

Waterfall spin-off models

Development in stages Level use of staff What types of testing is done?

LOT–25

Waterfall spin-off models – 2

Development in stages Level use of staff What types of testing is done?

Testing now entails both

Regression

Progression

LOT–26

Waterfall spin-off models – 3

What are the major types of spin off models?

LOT–27

Waterfall spin-off models – 4

What are the major types of spin off models? Variations involve constructing a sequence of

systems Incremental

Evolutionary

Spiral

LOT–28

Waterfall spin-off models – 5

What is their common modus operandi?

LOT–29

Waterfall spin-off models – 6

What is their common modus operandi?

Waterfall model is applied to each build

Smaller problem than original

System functionality does not change during abuild

LOT–30

Incremental model

Have high-level design at the beginning

Low-level design results in a series of builds Incremental testing is useful System testing is not affected

Level off staffing problems

LOT–31

Evolutionary model

First build is defined

Priorities and customer define next build

Difficult to have initial high-level design Incremental testing is difficult System testing is not affected

LOT–32

Spiral model

Combination of incremental and evolutionary

After each build assess benefits and risks Use to decide go/no-go and direction

Difficult to have initial high-level design Incremental testing is difficult System testing is not affected

LOT–33

Spiral model – advantage

Earlier synthesis and deliverables

More customer feedback

Risk/benefit analysis is rigorous

LOT–34

Rapid prototyping

Specification based life cycle model

Build quick and dirty system Good for risk analysis

Customer feedback

LOT–35

Rapid prototyping – 2

System testing is difficult Where is the specification?

Good for acceptance testing Emphasis is behaviour, not structure

LOT–36

Executable specifications

Specification based life cycle model

Extension of rapid prototyping

Specific behavioural models are built and executed Statecharts Finite state machines Petri nets Z specification language

Customer feedback as for rapid prototyping

LOT–37

Integration & system testing

Need to know difference between integration and systemtesting Avoid gaps and redundancies across levels Set testing goals appropriate for each level

Structural & behavioural views separate integration andsystem testing goals

LOT–38

Threads

What are threads?

LOT–39

Threads – 2

What are threads? Use cases Describe behaviour

Have threads at different levels What are the levels?

LOT–40

Thread levels

Have threads at different levels What are the levels?

Unit

Integration

System

LOT–41

Thread levels – 2

What are the threads at each level? Unit

??? Integration

??? System

???

LOT–42

Thread levels – 3

Unit Path in a program graph

Integration Path in a finite state machine

System level Data context and sequence of port events

LOT–43

Structural insights – integration testing

Assumes unit level testing completed

Can be seen as interface testing What about algorithms at higher levels?

Uses preliminary design What is preliminary design?

LOT–44

Structural insights – system testing

Requirements level

What is the difference between the following? Requirements Preliminary design

What-how and other definitions too vague Inevitability of intertwining specification and design

LOT–45

Behavioural insights

System level Deals with port boundaries

What the user sees and does Sequences of integration-level threads

Integration level Deals with boundaries between port and unit

Within the system Sequences of unit-level threads