2.3.2 Testing — OCR J277

🔒

Unlock Everything

£7.99/month

or £59/year

Why Testing?

Testing is used to find and fix errors (bugs) in a program before it is released. A well-tested program produces correct output for all inputs, including unexpected ones. No testing = undetected bugs = unreliable software.

Types of Testing

Type	Definition	Who does it?
Iterative testing	Testing carried out during development — testing each module/component as it is written	Developer
Final (terminal) testing	Testing carried out at the end of development once the complete program is built	Developer / Client
Alpha testing	In-house testing by the development team / company before public release	Developer team
Beta testing	Testing by a limited group of real users (outside the company) before public release	Real users (testers)

Test Data Types

When writing a test plan, OCR J277 expects you to use three categories of test data:

Category	Description	Example (age, 0–120)
Normal	Valid data the program should accept and process correctly	25, 50, 100
Boundary	Data at the very edge of the valid range (just inside, on, and just outside)	0, 1, 119, 120, -1, 121
Erroneous	Invalid data that should be rejected — wrong type, completely out of range	-10, 200, "abc", ""

Test Data Table — Worked Example

Program: accepts an age between 0 and 120 (inclusive).

Test	Category	Input	Expected Output	Actual Output	Pass/Fail
1	Normal	25	"Age accepted"	"Age accepted"	✅ Pass
2	Normal	75	"Age accepted"	"Age accepted"	✅ Pass
3	Boundary	0	"Age accepted"	"Age accepted"	✅ Pass
4	Boundary	120	"Age accepted"	"Age accepted"	✅ Pass
5	Boundary	-1	Error message	Error message	✅ Pass
6	Boundary	121	Error message	Error message	✅ Pass
7	Erroneous	"hello"	Error message	Error message	✅ Pass
8	Erroneous	500	Error message	Error message	✅ Pass

Types of Errors

Error Type	Description	Example
Syntax error	Code breaks the rules of the programming language — program cannot run	PINT "Hello" (missing 'R' in PRINT)
Logic error	Program runs but produces incorrect output — algorithm is wrong	Using + instead of - in a formula
Runtime error	Error that occurs while the program is running — causes a crash	Division by zero; index out of bounds

Iterative vs Final Testing

Iterative: test as you build — catch bugs early when they're cheap to fix; each module tested before the next is written
Final: whole program tested together — checks integration of all parts; more complex bugs found here
Both are used in practice — iterative during development, final before release

Exam tip: OCR J277 tests you on: (1) the three test data types — always give an example for each when asked; (2) the difference between iterative and final testing; (3) completing a test table (fill in expected output or category); (4) identifying error types from code/description. Boundary data is the most commonly missed — it includes values just inside, exactly on, AND just outside the boundary.

⚠️ Common Mistakes

Forgetting that boundary data includes BOTH the valid boundary (accept) AND just outside (reject)
Calling all wrong inputs "erroneous" — wrong TYPE is erroneous; wrong VALUE at the edge is boundary
Confusing syntax errors (won't run) with logic errors (runs but wrong output)
Only testing with normal data — boundary and erroneous tests are just as important to OCR J277
Writing "the program works" as expected output instead of the specific expected output

✅ Notes completed!

▶

Video coming soon

Click slide or press arrow keys to navigate

Worksheet — 2.3.2 Testing

8 questions · 24 marks

Q1Explain the purpose of testing a program. Why is it not enough to simply check the code looks correct?[2]

✅ Mark scheme

Testing runs the program with test data to find errors (bugs) that cause incorrect output, crashes, or unexpected behaviour [1]. Simply reading code (desk checking) may miss runtime errors, logic errors, or edge cases — the program must actually run with specific inputs to verify it behaves correctly [1].

Q2State the three types of test data and describe each with one example for a program that accepts scores from 0 to 100.[6]

✅ Mark scheme

Normal data: valid data within range [1] — e.g. 50 (should be accepted) [1]. Boundary data: data at the edge of the valid range [1] — e.g. 0, 1, 99, 100 (accept) and -1, 101 (reject) [1]. Erroneous data: invalid data that should be rejected [1] — e.g. "abc", -50, 200 (wrong type or far out of range) [1].

Q3Explain the difference between iterative and final testing.[3]

✅ Mark scheme

Iterative testing is carried out during development — each module is tested as it is written to find errors early [1]. Final testing is carried out at the end of development when the complete program is finished [1]. Iterative testing catches bugs early (cheap to fix); final testing checks that all parts work together correctly [1].

Q4Identify the type of error in each case: (a) OUTPUT "Helo" — intended "Hello" (b) total = price + tax, should be price * tax (c) division = 10 / 0[3]

✅ Mark scheme

(a) Logic error [1] — the program runs but produces the wrong output ("Helo" instead of "Hello"). (b) Logic error [1] — wrong operator used; runs but calculates incorrectly. (c) Runtime error [1] — division by zero causes a crash while the program is running.

Q5Describe the difference between alpha testing and beta testing.[2]

✅ Mark scheme

Alpha testing is done in-house by the development team before any public release [1]. Beta testing is done by a limited group of real users outside the company to find remaining bugs and usability issues before the full public launch [1].

Q6For a program that accepts integers from 1 to 10 only, complete the test table below by identifying the category and expected output for each test: Input: 5, Input: 1, Input: 0, Input: "five"[4]

✅ Mark scheme

5 = Normal → accepted / "Valid input" [1]. 1 = Boundary → accepted / "Valid input" [1]. 0 = Boundary → rejected / error message [1]. "five" = Erroneous → rejected / error message [1].

Q7Why is boundary testing particularly important? Give an example of a common programming mistake that boundary testing would catch.[2]

✅ Mark scheme

Boundary testing is important because errors often occur at the edge of allowed values rather than in the middle [1]. Example: a programmer uses age > 0 instead of age >= 0, so 0 is incorrectly rejected. Boundary test with 0 reveals this mistake [1].

Q8A syntax error prevents a program from running. Explain what a syntax error is and give one example.[2]

✅ Mark scheme

A syntax error occurs when the code breaks the rules (grammar) of the programming language, so the translator cannot convert it into executable code [1]. Example: missing keyword, misspelled command (e.g. PINT instead of PRINT), missing bracket, or incorrect indentation in Python [1].

out of 24 — self-mark above

Topic Quiz

Question 1 of 15

You scored

out of 15

Card 1 of 10

Click to reveal definition

🎉

Complete!

Term	Definition

Why Testing?

Types of Testing

Test Data Types

Test Data Table — Worked Example

Types of Errors

Iterative vs Final Testing

Worksheet — 2.3.2 Testing

Mini Test — 2.3.2 Testing