Testing Strategies

This lesson covers software testing strategies for the OCR A-Level Computer Science (H446) specification. Testing ensures that software is correct, reliable, and meets its requirements. You need to understand different testing types, techniques, and tools.

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Why Test Software?

Testing is essential because:

• It identifies bugs and defects before software reaches users.
• It verifies that software meets its requirements.
• It ensures software is reliable, secure, and performant.
• It reduces the cost of fixing errors -- bugs found early are much cheaper to fix.
• It builds confidence that the software works as expected.

Exam Tip: Know the difference between verification ("Are we building the product right?") and validation ("Are we building the right product?"). Testing contributes to both.

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Types of Testing

Unit Testing

Unit testing tests individual components (functions, methods, or classes) in isolation from the rest of the system.

def add(a: int, b: int) -> int:
    return a + b

# Unit tests
assert add(2, 3) == 5
assert add(-1, 1) == 0
assert add(0, 0) == 0