OCR J277: 2.3.2 Testing - In-Depth Lesson

1

Purpose & Types of Testing

Real-World Analogy: Building a Car

Imagine building a car. You don't just build the whole thing and hope it starts!

Purpose: We test to ensure the brakes work (Requirements) and the engine doesn't explode (Robustness).
Iterative: The mechanic tests the engine while it is sitting on the bench, before putting it in the car.
Final: The test driver takes the finished car on the track to see if everything works together.

Iterative Testing

Testing modules or small chunks of code during development.

Who? The Programmer.
When? During coding.

Final (Terminal) Testing

Testing the complete program at the end of production before release.

Who? Beta testers / Users.
When? At the end.

Checkpoint: Purpose & Types

I can Define the purpose of testing. I can Distinguish between Iterative and Final testing.

2

Syntax vs. Logic Errors

Syntax Error

Breaks the grammar rules of the language. The program will not run.

print("Hello" <-- Missing bracket

Logic Error

Code follows rules but design is flawed. Runs but gives unexpected output.

if age > 18: <-- Should be >=

I can Identify Syntax vs. Logic Errors.

3

Test Data Types

Scenario: A roller coaster ride. Height must be between 120cm and 200cm inclusive.

Visualizing the Logic

Invalid

119

Boundary

120

Normal

150

Boundary

200

Invalid

201

Erroneous: "Dave", "One Hundred" (Wrong Data Type entirely)

1. Normal Data

Data that is within the range and should be accepted. Ex: 150.

2. Boundary Data

Data on the edge of acceptability. Used to check for "Off-by-one" errors. Ex: 120, 200.

3. Invalid Data

Correct Type, but Wrong Value. Ex: 119, 201.

Checkpoint: Data

I can Select Normal, Boundary, Invalid, and Erroneous data. I can Create a robust test plan.

4

Refining Algorithms

Refining means taking code that has errors (found during testing) and fixing it to make it Robust.

Before (Buggy)


                        if age > 18:

                          print("Adult")

Refined (Robust)


                        if age >= 18:

                          print("Adult")

I can Refine algorithms to fix errors.

Testing & Robustness: The Complete Guide

Learning Checklist