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Edexcel 1CP2 · Topic 6 · 6.4b
Testing
Strategies
Normal · Boundary · Erroneous · Test Plans · Iterative Testing
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Edexcel GCSE Computer Science 1CP2
Types of Test Data
Three Categories to Know
Normal (valid)
: typical values the program should accept and process correctly. e.g. age = 17
Boundary
: values at the edge of the valid range — should just be accepted or just be rejected. e.g. age = 0, age = 120
Erroneous (invalid)
: values the program should reject — out of range, wrong type, or blank. e.g. age = -1, "abc", ""
Test Plan Example
Testing a score input (0–100)
Test
Type
Input
Expected Output
1
Normal
75
Score accepted
2
Boundary
0
Score accepted
3
Boundary
100
Score accepted
4
Erroneous
-1
Error message
5
Erroneous
"abc"
Error message
Iterative vs Final Testing
When to Test
Iterative testing
: test at every stage of development — after each subroutine or feature is added. Bugs are caught early and are easier to fix.
Final (terminal) testing
: test the complete program at the end — ensures all parts work together correctly (integration testing).
Edexcel favours iterative testing — it is more efficient as bugs do not accumulate
Alpha testing: internal testing by developers; Beta testing: external testing by real users
Exam Practice
Have a go at this question
Edexcel-style question
A program accepts ages between 16 and 65. Give one normal, one boundary, and one erroneous test value, and state the expected outcome for each.
6 marks
Normal: 30 — accepted [1+1]. Boundary: 16 or 65 — accepted [1+1]. Erroneous: 15, 66, or "hello" — rejected with error message [1+1].
Key Takeaways
What to Remember
Normal: typical valid value; Boundary: edge of valid range; Erroneous: should be rejected
Test plan: test #, type, input, expected output, actual output
Iterative: test during development; Final: test complete program
Alpha = developer testing; Beta = real users testing before full release