Development and Testing

7/28/2019 Development and Testing

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Development and testing

Done by: Anwaar al-hajri Grade:12/b

School: Madinat Al-Sultan Qaboos


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Introduction

Designing a system requires three stages:

Creating the system

Testing the system

Improving the system

The second and third stages may be repeated due to the

first stage being altered because of change in test results.

So they will be repeated until the system is complete.


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Creating data structures and program

modules

The data structures that have been designed will be

created using the software or programming language

recommended by system analyst.

The programmer will produce the program code to solve

the problem. The nature of the problem will determine the

amount of programming needed.


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Testing strategies

To make sure the system works, atest plan is produced by the system

analyst.

The test plan includes:

List of test data Expected results

Actual results

Comment on differences

between actual results andexpected results.


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Test data

There are three types of test data:

Normal data: the data that is acceptable or valid to the

system.

Extreme data: only used where a range of data is input.

Abnormal data: the data which is not acceptable or valid

to the system.


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Normal data

This type of data should not produce error messages from the

system.

Example:

In a payslip nobody works for more than 65 hours in a week,

and the lowest number of hours is zero if the worker is ill.

The normal data would be any number between 0 and 65,

including 0 and 65.

If these types of data produced error messages then there is a

problem with the system.


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Extreme data

Names and addresses can not be extreme data because

they have no ranges. Extreme data are the values at either

ends of the acceptable range.

Example:

In the payslip example the extreme data would be 0 and

65 only.


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Abnormal data

Abnormal data include letters when entered in a numericfield. Where a range of numbers is used abnormal data

would be numbers outside the range or letters.

Example:

In the payslip example abnormal data would be -1, 66,140 or Reem.


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Example of test plan for the payslip example

Test Testdata

Expectedresults

Actual results comment

Inputhours

worked

-1 Rejected Error message Abnormal data- the system

worked as expected

65 Accepted Wages calculated Extreme data- the system

worked as expected

0 Accepted Wages calculated

but result was 0

Extreme data- the system

worked as expected

40 Accepted Wages calculated Normal data- the system

worked as expected

140 Rejected Error message Abnormal data- the systemworked as expected

Reem Rejected Error message Abnormal data- the system

worked as expected


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Live data

Live data are those that have been used in the existing

system. It will be used because the outputs are already

known.

The original output will be compared with the output that

the new system has produced, if the outputs dont matchamendments will be made for the new system


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Improvements that could be needed as a

result of testing

The next step is to correct any mistakes before the system

is implemented. The analyst will correct any faults that were

identified as a result of testing.

The test plan should help in identifying the faults since it

shows the difference between expected and actual results.

If faults can still not be identified the next step is to see

where and when the differences occurred which can be

achieved using a process called single stepping.


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The End

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Development and Testing