EuroSTAR Software Testing Conference 2010 presentation on Branch out using Classification Trees for Test Case Design by Julie Gardiner. See more at: http://conference.eurostarsoftwaretesting.com/past-presentations/

1. Branch out using Classification Trees for test case design
1 © Grove Consultants UK
www.grove.co.uk
EuroSTAR 2010
Branch out using Classification
Trees for test case design
Julie Gardiner
Grove Consultants
26 Fallowfield
Orton Wistow
Peterborough
PE2 6UR. UK
Tel +44 7974 141436
email: julie@grove.co.uk
www.grove.co.uk
© Grove Consultants
Challenges we have as Test Managers
 convincing management scope of testing
 constant changes in projects
 explaining testing to others
 obtaining sign off from customers/business
 plus many others…

2. Branch out using Classification Trees for test case design
Hammer
(Boundary value analysis)
2 © Grove Consultants UK
www.grove.co.uk
Challenges we face in test design
 resources available
 time (design and execute)
 too many tests
 too few tests
 maintenance of the tests
 where to start
 lack of prioritisation
 what techniques to use
plan / control
analysis/design
impl / exec
exit / report
closure
Classification Trees
will focus on these
Hand drill
(Equivalence
classes)
The technique toolbox
Spanner/Wrench – (State
transition testing)
Screwdriver –
(Pairwise)

3. Branch out using Classification Trees for test case design
3 © Grove Consultants UK
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The power-tool in our toolbox
• variety of tools in one tool
• for different jobs
• variable speeds
• for different skills
• many functions
• sprit level, handle, wrist
strap, screwdriver holder etc
• mains and battery pack
• provides flexibility
• appeals to all people
• a MUST in your toolbox
Power tools are an essential item

4. Branch out using Classification Trees for test case design
4 © Grove Consultants UK
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Classification tree is the power tool
 a technique that EVERYONE needs
Fundamentals of Classification Trees
1. choose test object e.g. component or system
function
2. determine input domain
3. determine relevant factors affecting testing
4. form classifications by partitioning input domain
into classes
5. apply 3. and 4. recursively as appropriate
6. form combination table from classification tree and
identify test cases

5. Branch out using Classification Trees for test case design
Balance
enquiry
cash withdrawal
1
2
5 © Grove Consultants UK
Withdrawal
www.grove.co.uk
Example – ATM machine
Cash
Change pin
Statement
request
Another
transaction?
Classification tree - business tests (ATM)
type of transaction
3
4
statement
yes no
change pin
yes no
balance enquiry
screen print no
other
yes no valid invalid no

6. Branch out using Classification Trees for test case design
1
2
enough
funds?
1
2
6 © Grove Consultants UK
1.11
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Classification tree - system test
cash withdrawal
3
4
receipt?
yes no 10 100
amount
500
other
multiple
of 10
invalid
confirm
yes no yes cancel
5
Classification tree – component test
amount
digit
multiple of
10
not
multiple
of 10
special
chars
zero null chars
3
4
5
length
valid invalid
(2 or 3 digits)
<2 >3

7. Branch out using Classification Trees for test case design
early
bird discount
1
2
7 © Grove Consultants UK
www.grove.co.uk
Classification tree – EuroSTAR pricing
example pricing of conference
days at
conference
all days none
group
discount
yes no
tutorials days
chosen
on
date
none mon tues
member
supporting org
yes no after
date
3
4
5
before
date
both
one day
The “free battery pack” for flexibility
this power-technique has a free tool, providing:
• flexibility
• speed
• visibility
• interoperability with other tools

8. Branch out using Classification Trees for test case design
early
bird discount
1
2
8 © Grove Consultants UK
www.grove.co.uk
Test coverage
Class coverage
pricing of conference
days at
conference
all days none
group
discount
yes no
tutorials days
chosen
on
date
none mon tues
member
supporting org
yes no after
date
3
4
before
date
both
one day
Every class has been covered with these tests

9. Branch out using Classification Trees for test case design
early
bird discount
9 © Grove Consultants UK
Maximum
tests = 144
www.grove.co.uk
Combination coverage
pricing of conference
days at
conference
all days none
group
discount
yes no
tutorials days
chosen
on
date
none mon tues
member
supporting org
yes no after
date
before
date
both
one day
2 * 3 * 4 * 3 * 2
How can we reduce the test cases?
Test
Cases
Test
Cases
how?

10. Branch out using Classification Trees for test case design
10 © Grove Consultants UK
www.grove.co.uk
What the critics say…
 isn’t this just Equivalence partitioning
(classes)?
 what about Boundary Value analysis?
 how does it fit with other techniques?
 can you use it in exploratory testing?
 what about non-functional testing?
 too many tests are produced (some
unrealistic)
 can you assign risk?
 others?
When to use (or not use) CT

11. Branch out using Classification Trees for test case design
11 © Grove Consultants UK
www.grove.co.uk
Some of the industries actively using
Classification Trees
education
travel
retail
media
medical
financial
communications
airline
insurance
Summary: key points
 classification trees is a graphical way of
showing test cases
 can be applied at any level of testing
 it could be used in any organization
 it might complement other testing techniques
 use it to raise visibility of test cases and
improve maintainability

12. Branch out using Classification Trees for test case design
12 © Grove Consultants UK
www.grove.co.uk
Thank you!
Julie Gardiner
Grove Consultants
26 Fallowfield
Orton Wistow
Peterborough
PE2 6UR. UK
Tel +44 7974 141436
Email: julie@grove.co.uk
Resources:
Free tool: http://www.berner-mattner.com
Other tools: Hitex, Razorcat