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40 lines
2.4 KiB
Markdown
40 lines
2.4 KiB
Markdown
# FAQ
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## Can I test the native features of React Native apps?
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Short answer: no.
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React Native Testing Library does not provide an entire React Native runtime since that would require running on a physical device
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or iOS simulator/Android emulator to provision the underlying OS and platform APIs.
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Instead of using React Native renderer, it simulates only the JavaScript part of its runtime
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using [React Test Renderer](https://reactjs.org/docs/test-renderer.html) while providing queries
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and event APIs ([User Event](/react-native-testing-library/13.x/docs/api/events/user-event.md), [Fire Event](/react-native-testing-library/13.x/docs/api/events/fire-event.md)) that mimicking certain behaviors from the actual runtime.
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You can learn more about our testing environment [here](/react-native-testing-library/13.x/docs/advanced/testing-env.md).
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This approach has specific benefits and shortfalls. On the positive side:
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- it allows testing most of the logic of regular React Native apps
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- it allows running tests on any OS supported by Jest or other test runners, e.g., on CI
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- it uses much less resources than full runtime simulation
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- you can use Jest fake timers
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On the negative side:
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- you cannot test native features
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- it might not perfectly simulate certain JavaScript features, but we are working on it
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The [User Event interactions](/react-native-testing-library/13.x/docs/api/events/user-event.md) solve some of the simulation issues, as they offer more realistic event handling than the basic [Fire Event API](/react-native-testing-library/13.x/docs/api/events/fire-event.md).
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## Should I use/migrate to `screen` queries?
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There is no need to migrate existing test code to use `screen`-bases queries. You can still use
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queries and other functions returned by `render`. The `screen` object captures the latest `render` result.
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For new code, you are encouraged to use `screen` as there are some good reasons for that, which are described in [this article](https://kentcdodds.com/blog/common-mistakes-with-react-testing-library#not-using-screen) by Kent C. Dodds.
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## Should I use/migrate to User Event interactions?
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We encourage you to migrate existing tests to use the [User Event interactions](/react-native-testing-library/13.x/docs/api/events/user-event.md), which offer more realistic event handling than the basic [Fire Event API](/react-native-testing-library/13.x/docs/api/events/fire-event.md). This provides more confidence in the quality of your code.
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