If you've ever been stuck on what tests to write for your code, Jest's coverage reports can be a great tool for showing what sections of your codebase are not tested yet. It becomes even more powerful when used in combination with Continuous Integration (CI), as it can be automated and even block pull requests from merging, which we'll show in this video.
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00:00 - What we'll cover
01:09 - Project overview
03:10 - When is coverage useful?
08:04 - Exploring the report in the browser
15:25 - Increasing coverage with a test
20:20 - Covering conditionals (branches)
24:49 - Gotchas with random outcomes in tests
28:32 - Adding a config for coverage customization
33:58 - Expanding coverage on a previously untested file
36:44 - Failing a test run on poor coverage
43:05 - Pull request workflow example (CI)
52:50 - Wrap-up
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twitter: https://twitter.com/JimmyDCleveland
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