85 lines
3.4 KiB
Markdown
85 lines
3.4 KiB
Markdown
# Contributing: Tests
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> Testing is an opinionated topic. Here is a rough overview of our testing
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> philosiphy. See something you want to discuss or think should be changed? Open
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> a PR and let's discuss.
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Why do we write tests?
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- Increase confidance
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## Kinds of Tests
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Test's buy us confidence, but not all tests are created equal. Each kind of test
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has a different cost to write and maintain. More costly tests
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| Test Type | Example | Speed | Cost |
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| ----------- | -------------------------------------------------------------------- | ---------------- | ------------------------------------------------------------------------ |
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| Static | `addNumbers(1, '2')` was called with a `string`, `int` was expected. | :rocket: Instant | :money_with_wings: |
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| Unit | `addNumbers(1, 2)` returns expected result `3` | :airplane: Fast | :money_with_wings::money_with_wings: |
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| Integration | | :running: Okay | :money_with_wings::money_with_wings::money_with_wings: |
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| End-to-end | When I click "Sign In", the page navigates to the dashboard. | :turtle: Slow | :money_with_wings::money_with_wings::money_with_wings::money_with_wings: |
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### Static Code Analysis
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Modern tooling gives us this "for free". It can catch invalid regular
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expressions, unused variables, and guarantee we're calling methods/functions
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with the expected paramater types.
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Example Tooling:
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- [ESLint][eslint-rules]
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- [TypeScript][typescript-docs] or Flow
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Static code analysis can't test business logic.
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### Unit Tests
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...
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#### What should be unit tested?
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Follow the top level exports. Anything that is exposed as public API should have
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unit tests. These are th
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#### What should NOT be unit tested?
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You're testing implementation details if:
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- Your test does something that the consumer of your code would never do.
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- IE. Using a private function
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- A refactor can break your tests
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### Integration Tests
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...
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### End-to-End Tests
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...
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## Further Reading
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- [Assert(js) Conf 2018 Talks][assert-js-talks]
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- [Write tests. Not too many. Mostly integration.][kent-talk] - Kent C. Dodds
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- [I see your point, but…][gleb-talk] - Gleb Bahmutov
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<!--
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Links
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-->
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<!-- prettier-ignore-start -->
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[eslint-rules]: https://eslint.org/docs/rules/
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[typescript-docs]: https://www.typescriptlang.org/docs/home.html
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<!-- Talks -->
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[assert-js-talks]: https://www.youtube.com/playlist?list=PLZ66c9_z3umNSrKSb5cmpxdXZcIPNvKGw
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[kent-talk]: https://www.youtube.com/watch?list=PLV5CVI1eNcJgNqzNwcs4UKrlJdhfDjshf
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[gleb-talk]: https://www.youtube.com/watch?v=5FnalKRjpZk
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<!-- Images -->
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[testing-trophy]: https://twitter.com/kentcdodds/status/960723172591992832?ref_src=twsrc%5Etfw%7Ctwcamp%5Etweetembed%7Ctwterm%5E960723172591992832&ref_url=https%3A%2F%2Fkentcdodds.com%2Fblog%2Fwrite-tests
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[aaron-square]: https://twitter.com/Carofine247/status/966727489274961920
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[gleb-pyramid]: https://twitter.com/Carofine247/status/966764532046684160/photo/3
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[testing-pyramid]: https://dojo.ministryoftesting.com/dojo/lessons/the-mobile-test-pyramid
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[testing-dorito]: https://twitter.com/denvercoder/status/960752578198843392
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<!-- prettier-ignore-end -->
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