05-Testing - dolinski.co.uk | home

• Importance of testing
• Difference between Errors and Faults
• The purpose of test data
• Importance of:
– Testing
– Test Plans
• Whenever a system has been implemented it
needs to be thoroughly tested to ensure it works.
• The amount of testing that takes place depends
on the system:
– A system which monitors nuclear reactions in a power
station needs to be more thoroughly tested compared
to a simple stock take system, for example.
• In any case, all new systems should be tested
using a particular procedure.
• A testing procedure is created which forms a test plan.
• Through testing you can establish:
– That the new system meets the end-user’s requirements.
– That the new system processes data and outputs correct
• Testing can also help boost the confidence of the enduser’s. If they know the system has worked under
testing they will be more confident in using it!
• It is important to understand the difference
between an error and a fault.
– These are human mistakes. If a user
inputs data into the system in the
incorrect format the system will
return an error.
– Computer systems should prevent
users doing this were possible
through validation checks and by
restricting access to particular
features of an application when they
are not needed for the current
– Faults are embedded within the system.
– They can cause system failures.
– They are often called ‘bugs’.
• The ‘blue screen of death’ is an error message
that appears when Microsoft’s operating
systems are not able to recover from an error.
• If your system can minimise human error and
doesn’t contain bugs then you could consider
it to be a reliable system.
• Testing ensures that a system is reliable.
• If testing doesn’t take place then you can’t
claim a system is reliable.
• When a new system is released it often
contains bugs that weren’t discovered in
• The software developers often release a series
of patches or updates to address these
• The data that is selected for testing is really
• There are three types of test data which
should be used for each particular thing you
are testing:
– Normal data
– Extreme data
– Erroneous (or abnormal) data
• This is data which is:
– Correct
– Which should not generate any errors
– Data which is likely to be used everyday
• This is data which is:
– Correct
– Tests the boundaries of a range
• For example, data inputted into a field might need to
be within a range of 1-100. Two tests should be carried
out – Test the input of 1 and test the input of 100.
• This is data which is:
– Incorrect
– Outside of boundary tolerances
– Making use of incorrect data types
– Making use of invalid characters ([? # + \] etc)
• Test plans need to be created before any testing takes
• These should be well thought out so that all aspects of
the system are tested.
• Test plans should ensure that tests cover:
The requirements
Validation Routines
A comparison of the actual performance against the design
Test #
Description of test
Type of test
Data used
Expected Result
A unique identifier for each test
Simple description of what is being tested
Normal, Extreme, Erroneous
What data will be entered to run the test and where it is to be
What you expect to happen when you run the result. If normal or
extreme, you expect a correct result. If erroneous it should return
an error.
• The test plan needs to be detailed enough to
allow someone else to look at it and
understand what tests took place.
• Any test which returns an unexpected result
will need to be analysed and retested after
modifications have taken place.
• Describe the importance of a test plan.
• Explain when a test plan needs to be
• Explain the purpose of test data.
• Explain the difference between normal,
extreme and erroneous test data.

similar documents