Testing and Debugging

This lesson covers the types of software testing, testing strategies, and the use of appropriate test data. The OCR H446 specification requires you to understand unit, integration, system and acceptance testing, black-box and white-box testing, alpha and beta testing, and the three types of test data.

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Why Testing Matters

Testing is essential to:

• Find defects (bugs) before the software is released to users.
• Verify that the software meets its requirements specification.
• Validate that the software does what the user actually needs.
• Improve quality and reliability.
• Reduce cost — finding bugs early is far cheaper than fixing them after release.

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Levels of Testing

Testing is carried out at different levels, from individual components to the complete system.

Unit Testing

Aspect	Detail
What is tested	Individual components — typically a single function, method or class
Who does it	The developer who wrote the code
When	During development, as each unit is written
Goal	Verify that each unit works correctly in isolation
Tools	Automated testing frameworks (e.g. JUnit, pytest, NUnit)