Testing & Software Quality


Nov 5, 2013 (4 years and 8 months ago)


Testing & Software Quality

Seminar on software quality


Karipekka Kaunisto


Role of testing in quality assurance

Challenges of software testing

What is test automation?

Test automation: Possible benefits

Common pitfalls of test automation



Role of testing in quality assurance

Quality controlling

Final product meets it’s requirements

Find potential errors and flaws

Enforce standards and good design

Regression testing

Improving quality

Preventive testing

Find cause of an error not just symtoms

Role of testing...

Testing as supportive action

Data collected during testing can be used
to develop various quality metrics

These can be used to some extend when
evaluating system quality and maturity

However, numbers alone don’t solely
assure good quality!

Examples of poor testing

A major U.S. retailer was hit with a large govermental
fine in October of 2003 due to web site errors that
enabled customers to view one anothers' online orders

In early 1999 a major computer game company recalled
all copies of a popular new product due to software
problems. The company made a public apology for
releasing a product before it was ready

A retail store chain filed suit in August of 1997 against a
transaction processing system vendor (not a credit card
company) due to the software's inability to handle credit
cards with year 2000 expiration dates

Challenges of software testing

Complexity of testing

Even in a seemingly simple program
there can be potentially infinite number
of possible input and output
permutations to test

What about large software systems with
complex control logic and numerous
dependencies on other modules and
entire systems?

Complexity of testing

=> It is not feasible to get even close to
testing all combinations and thus finding all
possible errors!

Tester needs to carefully create test set in
a way that minimises risk of fatal errors in
final product

Related problem: How do you know when
to stop testing?

Acceptable risk level

Managing large test sets

Various general techniques have been
introduced for managing test sets

Partitioning to smaller subsets

Testing special cases (boundaries,
special values etc.)

Testing most important functions only
(focus testing)

Invalid inputs and data

Program flow and code coverage testing

Are we ready to ship?

Even with all the techniques available it will
require tester’s personal expertise and
domain knowledge to create test plan and
make the final decision to approve the

Business issues may also affect on this:
Risk of errors vs. risk of delay

Plan and test effort correlate quite well to
quality controlling role of testing

Other challenges

Testing activities require significant amount
of time and resources of the project =>
Delays, hasty testing

Testing is often regarded as dull,
monotonous and laborous part of software
development => Poor effort

System architecture is often quite complex,
which require special testing effort =>
Reliability suffers, all tests not even
possible manually

What is test Automation?

”The management and performance of
test activities to include the
development and execution of test
scripts so as to verify test requirements,
using an automated test tool”.

Rashka & Paul

”Testing supported by software tool”.

Faught, Bach

Automation in practice

Tester describes the test cases for tool by
using special scripting language designed
by tool developers

Some tools may also include graphical
interface and recording options but in
practise scripting has to be used

Script should also specify how tool is
supposed to interpret the correct results of
any given test case

Tool then takes care of executing specified
tests and examining the results

Automation in practise (cont.)

Result validation includes text outputs,
elapsed time, screen captures etc.

Can be very challenging part to do
automatically and may require some
human intervention in some cases!

Evaluation results are presented in clear
test reports that can be used to examine
results of test round

Produced reports can also be used to
gather data for various quality metrics

Areas of test automation

Automation suits mainly on testing
that requires repeated effort of
similar tests cases

Regression testing

Portability testing

Performance and stress testing

Configuration testing

Smoke testing


Possible benefits

More reliable system

Improved requirements definition

Improved performance (load & stress)

Better co
operation with developers

Quality metrics & Test optimisation

Enchanced system development life cycle

Benefits (2)

More effective testing process

Improved effort in various sub
areas like
regression, smoke, configuration and
platform compatibility testing

Ability to reproduce errors

Dull routine tests can be executed
without human intervention

hours testing”

More effective...

Execution of tests that are not possible

Better focus on more advanced testing

Enchanced business expertise

Benefits (3)

Reduced test effort and schedule

Initial costs of automation are usually
very high

Payback comes later on (possibly quite
much later) when team has adopted the
process and use of tools

Pitfalls of test automation

Automatic test planning and design

There are no tools that can generate
these automatically!

Requires human expertise and domain

Tool just does what it is scripted to do
and nothing else

Pitfalls (2)

Immeadiate cost and time savings

On the contrary introduction of
automation and new tools will increase
the need of resources!

Automation process must be planned,
test architecture created, tools
evaluated, people trained, scripts

= Lot’s of work


Potential savings will be archieved
(much) later on when organisation has
’learned’ the process and created needed
infrastructure for it

If automation is introduced poorly,
savings will never be gained at all!

In the worst case automation can just
mess things up

Pitfalls (3)

One tool does it all

Wide array of operating systems,
hardware and programming languages

Very different systems and architectures
are often used

Testing requirements differ depending on
system and project

Result analysis differ (graphical, text,
time etc.)

Pitfalls (4)

Automation requires no technical skill

Tools rely solely on scripts when
executing tests

Maintainable and reusable script building
requires good programming skills and
knowledge of the tool

Testers may have to be able to use
several different tools with different
scripting technologies!

Pitfalls (5)

100% test automation

Even if automation succeeds it cannot
completely replace manual testing

Some tests must be conducted manually
and others require at least some human

Automation is really useful only with test
cases that are executed repeatedly over
time (regression)

Other related tools

Code analyzers

Coverage analyzers

Memory analyzers (purifiers)

Web test tools

Test management tools


Testing has significant role in software
quality assurance

Automation, when implemented properly
can further improve test effort and thus
lead to improved quality

However many automation attempts have
failed because of unrealistic expectations
and inproper introduction of automation


Dustin E., Rashka J., Paul J.: Automated
Software Testing: Introduction,
Management and Performance. Adison
Wesley, 1999

Craig R. and Jaskiel S.: Systematic
Software Testing, Artech House Publishing,

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