20 lines
913 B
Markdown
20 lines
913 B
Markdown
---
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title: "Jest "
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ring: assess
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quadrant: tools
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---
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[Jest](https://facebook.github.io/jest/) is a JavaScript testing framework by facebook to test JavaScript code **and** React applications / components.
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We started using Jest (and [watchmen](https://github.com/facebook/watchman)) instead of Karma because it:
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- gives us integrated mocking library
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- gives us integrated support for testing "promises"
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- gives us integrated code coverage report
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- automatically runs tests related to changed files (instead of all tests)
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- gives us parallel test execution
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- gives us snapshot testing for React components
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It is easy to set up.
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And even if you have a running setup with Karma/Chai you can easily replace Karma with Jest.
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With a small [workaround](https://medium.com/@RubenOostinga/combining-chai-and-jest-matchers-d12d1ffd0303#.3callo273), Chai and Jest test matchers work fine together. |