Testing & implementation system 1-wm

Testing & Implementation System
WIWIK MUSLEHATIN
11453201902
CHAPTER 1
Fundamentals of Testing
Departement of Information System
Faculty of Science and Technology
UIN SUSKA RIAU
2017

Agenda :
Introduction
Software System Contex
Causes of software defects
Role of testing in software
development, maintenance and
operations

Testing is Necessary,
Because :
1. Describe, with examples, the way in which a defect in software can cause harm
to a person, to the environment or to a company. (K2)
2. Distinguish between the root cause of a defect and its effects. (K2)
3. Give reasons why testing is necessary by giving examples. (K2)
4. Describe why testing is part of quality assurance and give examples of how
testing contributes to higher quality. (K2)
5. Recall the terms 'mistake', 'defect', 'fault', 'failure' and the corresponding terms
'error' and 'bug'. (K1)
6. Explain the fundamental principles in testing. (K2)

Introduction
• Testing is necessary because we all make mistakes.
• Some of those mistakes are unimportant, but some of
them are expensive or dangerous. We need to check
everything and anything we produce because things can
always go wrong
• Humans make mistakes all the time.

Introduction
• Because we should assume our work contains mistakes,
• we all need to check our own work.
• However, some mistakes come from bad assumptions and
blind spots,
• we might make the same mistakes when we check our
own work as we made when we did it

Software System Contex
Testing Principle - Testing is context dependent
• Not all software systems carry the same level of risk and not all
problems have the same impact when they occur.
• A risk is something that has not happened yet and it may never
happen; it is a potential problem

Causes of software defects
• If someone makes an error or mistake in using the
software, this may lead directly to a problem - the
software is used incorrectly and so does not behave as
we expected.
• These are called defects or sometimes bugs or faults.
Remember, the software is not just the code; check the
definition of software again to remind yourself.
• When the software code has been built, it is executed
and then any defects may cause the system to fail to
do what it should do (or do something it shouldn't),
causing a failure. Not all defects result in failures; some
stay dormant in the code and we may never notice
them.

• Difficult for people to find their own mistakes while building a
product. Defects in software, systems or documents may result in
failures, but not all defects do cause failures. We could argue that if a
mistake does not lead to a defect or a defect does not lead to a
failure, then it is not of any importance - we may not even know
we've made an error.
• Our fallibility is compounded when we lack experience, don't have the
right information, misunderstand, or if we are careless, tired or under
time pressure. All these factors affect our ability to make sensible
decisions - our brains either don't have the information or cannot
process it quickly enough.

• Additionally, we are more likely to make errors when dealing with
perplexing technical or business problems, complex business
processes, code or infrastructure, changing technologies, or many
system interactions.
• This is because our brains can only deal with a reasonable amount of
complexity or change - when asked to deal with more our brains may
not process the information we have correctly.

When we think about what might go wrong we have to consider defects
and failures arising from:
1. errors in the specification, design and implementation
of the software and system;
2. errors in use of the system;
3. environmental conditions;
4. intentional damage;
5. potential consequences of earlier errors, intentional
damage, defects and failures.

Role of testing in software development,
maintenance and operations
• Rigorous testing is necessary during development and maintenance to identify
defects, in order to reduce failures in the operational environment and increase the
quality of the operational system.
• This includes looking for places in the user interface where a user might make a
mistake in input of data or in the interpretation of the output, and looking for
potential weak points for intentional and malicious attack.
• Executing tests helps us move towards improved quality of product and service, but
that is just one of the verification and validation methods applied to products.
Processes are also checked, for example by audit. A variety of methods may be
used to check work, some of which are done by the author of the work and some
by others to get an independent view

Graham, Dorothy, et al. “Foundation of software Testing ISTBQ
Sertification”. Chapter 1 Fundamentals of Testing. 2011

Testing & implementation system 1-wm

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