Unit Tests for Edge Cases, Not Just Happy Paths
A function works for one example but fails on empty input or boundaries. This guide gives you a small, testable way to approach the issue before changing a live system.
A practical workflow
- List the contract, then test empty, malformed and near-limit cases that matter to users.
- Keep fixtures small and name tests for observable behavior rather than internal methods.
What to check
Avoid tests that duplicate the implementation line for line; they may pass with the same mistake. Compare the result with the original problem and record what changed. If a measurement or test does not support the change, revisit the assumption rather than adding more complexity.
Keep the experiment small enough to reverse. Document the starting state, the change and the result so another person can repeat the process. Product menus and versions can change, so check the current documentation for your environment.
Official reference: Read the documentation.