🧩 What is Unit Testing?

Unit testing is a software testing method where you test individual pieces of your code (usually functions or methods) to make sure they work as expected—all on their own.
Think of it as checking each LEGO brick before building the whole castle.

✅ Why Do We Need Unit Testing?

• Catch Bugs Early: Find problems before they snowball into bigger issues.
• Safe Refactoring: Confidently change code, knowing tests have your back.
• Documentation: Good unit tests show how functions are supposed to behave.
• Speeds Up Development: Less time debugging, more time building features.

🧪 What Do We Test in Unit Testing?

• Functions & Methods: Core logic, business rules, calculations, etc.
• Edge Cases: Unusual inputs, invalid data, or unexpected conditions.
• Return Values: Are we getting the results we expect?
• Error Handling: Does the code handle failures gracefully?

⚠️ Common Challenges in Unit Testing

• Mocking Dependencies: Sometimes hard to isolate code if it calls databases, APIs, etc.
• Flaky Tests: Unstable tests that sometimes pass, sometimes fail (super annoying).
• Coverage Gaps: Missing tests for edge cases or tricky logic.
• Maintenance: Keeping tests up to date as code evolves.