Testing React Applications: A Practical Guide

Tests are your safety net — they let you refactor with confidence and ship changes without fear. The goal is not “as many tests as possible”; it’s confidence in the critical paths.

If your test suite feels slow or fragile, it usually means you’re testing the wrong thing. In practice, you can ignore a lot of “perfect coverage” advice and focus on a few high-signal habits.

What to test (a simple rule)

• Unit tests: small, fast checks for logic and pure functions.
• Integration tests: components + data + user flows (most value per test).
• E2E tests: a few happy-path checks across the whole app.

High-signal testing habits

• Prefer user-facing assertions (what the user sees/does).
• Use accessible queries first (roles, labels).
• Mock at the boundary (network) instead of mocking implementation details.

Things to avoid

• ~~Testing internal component state~~ when behavior is what matters.
• ~~Sprinkling test IDs everywhere~~ as a first choice.
• Overusing snapshots that fail for harmless UI changes.

Wrap-up

Start small: one integration test for your most important flow, then add unit tests for tricky logic. Over time, your tests become living documentation that helps you move faster.