• For Facebook’s native apps we use a system called “snapshot testing”: a snapshot test system that renders UI components, takes a screenshot and subsequently compares a recorded screenshot with changes made by an engineer.
• As a result many people stopped writing tests altogether which eventually led to instabilities.
• With snapshot testing I do not need the output files, the snapshots are generated for free by Jest!
• Engineers frequently told us that they spend more time writing a test than the component itself.
• import renderer from ‘react/lib/ReactTestRenderer’ ; test ( ‘Link renders correctly’ , ( ) = > { const tree = renderer .

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