Testing that matters, not chasing coverage numbers

Tests exist to give you confidence to change code, not to decorate a percentage.

# Test behavior, not internals

Focus on outcomes users care about; tests coupled to implementation details break on every refactor.

# The testing pyramid

Many fast unit tests at the base, fewer integration and end-to-end tests at the top, to balance reliability and speed.

• Write a test for a bug before fixing it
• Keep tests independent and deterministic
• Prioritize tests for error-prone logic

Good tests are the safety net that lets you move fast.