Unit Tests

What is unit testing

= testing the smallest pieces of code (usually functions or methods) in isolation to verify they behave correctly

Basic things unit tests should cover

• positive tests/normal cases
• negative tests/edge cases
• error handling: check that the function raises appropriate errors for bad input
• code coverage: test all logic branches (if/else, loops, early returns) are actually executed during the tests
• consistency & idempotence
  • run the function multiple times to ensure it gives the same result if expected

Key Principles

• test one thing at a time
• keep tests fast
• tests should be deterministic
• run often