2.4 Testing, Refinement and Evaluation
Plan and execute tests, diagnose faults, refine the solution and evaluate correctness, efficiency and fitness for purpose.
How to study WJEC GCSE Computer Science
Learn the computing principle, apply it to the named system or scenario, trace the data and control flow, and test the result against requirements.
Core concepts
Concept 1
Test plans, expected and actual results, normal, boundary, extreme and erroneous data
Exam cue: Identify the current WJEC unit, the command word and whether the task asks for knowledge, application or computational analysis.
Concept 2
Syntax, logic and runtime fault diagnosis, debugging, regression testing and evidence-led refinement
Exam cue: Predict each expected result before execution, capture evidence, isolate the cause of any difference and rerun affected and regression tests.
Concept 3
Efficiency, usability, robustness, maintainability and evaluation against requirements and success criteria
Exam cue: Use precise terminology, trace inputs and state changes, and test the answer against the data, scenario or program behaviour.
Risk pitfalls and guardrails
Calling a program fully tested after one successful normal input or listing improvements without evidence and a requirement-based reason.
Guardrail: Avoid generic descriptions, unchecked traces and cross-board assumptions; make every answer depend on the named data, system, algorithm or scenario.
Importing the legacy WJEC structure, a different board's content or a Foundation/Higher tier assumption.
Guardrail: Use qualification code 3460QS or 3460CS and the current two-unit untiered structure; do not import a legacy or cross-board route.
Giving a generic description without applying it to the named system, data set, algorithm or pre-release scenario.
Guardrail: Practice cannot replace the annual live brief, specified Python environment, clean-copy rule, restricted examination files or Surpass upload process.
Memory anchors
Normal test data
Valid, representative input that the program should accept and process normally.
Boundary and extreme data
Values at or near permitted limits used to check comparison and validation behaviour.
Erroneous data
Invalid input used to confirm that the program rejects or handles it safely.
Regression testing
Repeating existing tests after a change to check that previously working behaviour remains correct.
Refinement
An evidence-led change that improves correctness, efficiency, usability, robustness or maintainability.
Fitness for purpose
The degree to which the solution satisfies its users, requirements, constraints and success criteria.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
Which description identifies normal data in a test plan?
What is boundary test data?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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