The systems life cycle: development and testing Cambridge IGCSE Information & Communication Technology revision
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In plain words
A new system is built, and then people try hard to break it. Finding a fault before the system goes live costs little. Finding it afterwards, with real customers' data, can cost a great deal.
6 things to know
- A system is tested before implementation to make sure it works as intended and that errors are found and corrected.
- Each module is tested by itself, then each function, and finally the whole system.
- The data structures, file structures, input formats, output formats and validation routines are all tested.
- A test plan lists, for each test, the test data, the expected outcome, the actual outcome and any remedial action needed.
- Normal data is data that should be accepted. Abnormal data should be rejected. Extreme data is at the limits of what is accepted.
- Live data is real data that has been used with the existing system. Its results are already known, so the new system's results can be compared with them.
Worked example
A field accepts ages from 11 to 18. Suggest one item each of normal, abnormal and extreme test data.
- Normal: 14. It should be accepted.
- Abnormal: 25, or the word "twelve". It should be rejected.
- Extreme: 11 or 18. They are on the limits, and should be accepted.
Tips and tricks
- Extreme data is accepted: it is the largest or smallest value allowed. Do not confuse it with abnormal data, which is outside the limits.
- A test plan has four columns to remember: test data, expected outcome, actual outcome, remedial action.
It lands in your notebook with its questions as flashcards.
The systems life cycle: development and testing: 5 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
A field accepts marks from 0 to 50. Which is extreme data?
It is the largest value that should be accepted.
A field accepts marks from 0 to 50. Which is abnormal data?
It is outside the range and should be rejected.
What does a test plan include?
Any remedial action is recorded as well.
What is live data?
Its results are already known.
Why is a system tested before it is implemented?
Faults found later are harder and costlier to fix.
Quiz
5 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
2 questions, 5 marks. Write your answers on paper, then check them.
The systems life cycle: development and testing
Cambridge IGCSE Information & Communication Technology 0417 · 5 marks · papermunch.org
Name ______________________________ Date ______________
Describe what is meant by normal, abnormal and extreme test data.[3]
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Normal data is typical data that should be accepted. Abnormal data is data that should be rejected, such as a value outside the range. Extreme data is at the limit of the acceptable range.
Explain why live data is used to test a new system.[2]
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It is real data that has already been processed by the existing system. The results from the new system can be compared with the known results.
Answers: The systems life cycle: development and testing
- 1. Normal data is typical data that should be accepted. Abnormal data is data that should be rejected, such as a value outside the range. Extreme data is at the limit of the acceptable range.
- 2. It is real data that has already been processed by the existing system. The results from the new system can be compared with the known results.