Snapshot Testing: Lock In Your UI's Rendered Output
Snapshot testing catches unintended UI changes by comparing a component's rendered output to a saved 'golden' version. Use it to ensure UIs don't break during refactors. The biggest footgun is blindly updating snapshots, which can approve bugs as correct.
Snapshot testing is like a 'diff' for your UI, catching unintended changes by comparing a component's rendered output (e.g., HTML) to a saved 'golden' version. It's ideal for ensuring stable components don't break during refactors or dependency updates. The test fails if the new output doesn't match the saved snapshot. The main danger is blindly running `jest -u` to update snapshots without first confirming the change is intentional, otherwise you risk approving a bug as the new correct state.
Read the original → jestjs.io
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