Building High-Quality JavaScript Tools
summary
Jest gets rebuilt incrementally: a new filesystem analyzer and smarter caches plus parallel worker scheduling speed tests at Facebook from thousands to tens of thousands of suites, and performance improvements ship in small steps. Output and an immersive watch mode get rewritten for clearer failure signals, tests gain toMatchSnapshot() files that record outputs for quick regression checks, a jest-codemods tool migrates projects automatically, and adoption rises — hundreds of companies and a 35% growth in tests at Facebook.
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chapters (17)
- 0:00Introduction
- 1:58Testing at Facebook
- 3:09Product mindset for testing
- 5:01Performance at scale in Jest
- 7:38Output and assertions
- 9:28Watch mode and DX
- 10:13Snapshot testing
- 12:48Multiprocess runner
- 14:14Delightful and zero-config
- 16:06Reusable packages
- 18:23Standardizing testing
- 20:16Open-source community
- 21:04Documentation translation
- 21:49Code mods for frameworks
- 24:18Impact and growth
- 25:07Biggest Jest release
- 25:54Future of Jest
