Test data: normal, abnormal, extreme and boundary
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The teaching part (1 min) is free to watch. A free account opens the whole lecture: 8 practice questions, 2 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- Break it before they do
- Why test with chosen data?
- Normal and abnormal
- Extreme and boundary
- A mark from 0 to 100
Read the transcript of the teaching part
Last time
Before we start: last time, in Validation and verification, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
Break it before they do
A program that works for the number fifty may still fail for zero, for a hundred, or for a word. Testers choose their data carefully, to try to break the program. There are four kinds of test data. Learn what each one is for, and what the program should do with it.
Why test with chosen data?
A program is tested by running it many times, with different test data. The aim is to check that it works as required, and to find errors. Good test data includes values that should be accepted, and values that should be rejected.
Normal and abnormal
Normal data is within the range, and should be accepted. Abnormal data is outside the range, or the wrong type, and should be rejected. Abnormal data includes words, decimals, and numbers that are too big or too small.
Extreme and boundary
Extreme data is the largest and smallest values that are accepted. Extreme data is always accepted. Boundary data comes in pairs, on each side of a limit. One value of the pair is accepted, and the value just outside it is rejected.
A mark from 0 to 100
The rule: a whole number mark from zero to one hundred. Normal: fifty and seventy-three are accepted. Abnormal: minus twenty, one hundred and fifty, the word ten, and forty-five point five are rejected. Extreme: zero and one hundred, accepted. Boundary: zero with minus one, and one hundred with one hundred and one.
How often it comes up
The whole chapter: Test Data.
Chapter 7.5: Test data
- Test data: normal, abnormal, extreme and boundary 6 min
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