--- title: React Native Harness: Fast, Real-Device Testing for... description: React Native Harness is a new testing framework from Callstack that fills the gap between Jest (fast but no native execution) and E2E tools like Detox or... canonical: https://daily.dev/posts/react-native-harness-fast-real-device-testing-for-native-modules-hqorjhowy twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: React Native Harness: Fast, Real-Device Testing for Native Modules | daily.dev og:description: React Native Harness is a new testing framework from Callstack that fills the gap between Jest (fast but no native execution) and E2E tools like Detox or... og:url: https://daily.dev/posts/react-native-harness-fast-real-device-testing-for-native-modules-hqorjhowy og:image: https://api.daily.dev/og/posts/HQoRJHOwy.png og:image:alt: React Native Harness: Fast, Real-Device Testing for Native Modules og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # React Native Harness: Fast, Real-Device Testing for Native Modules **[Callstack Blog](https://daily.dev/sources/callstack-blog)** · 6 min read · 0 upvotes · 0 comments ## Summary React Native Harness is a new testing framework from Callstack that fills the gap between Jest (fast but no native execution) and E2E tools like Detox or Maestro (realistic but slow and complex). It lets developers write Jest-style tests that run directly on real devices or emulators, making it ideal for validating native modules. Tests use a familiar API with Vitest's expect library, support lifecycle hooks, mocking via @vitest/spy, and work in CI/CD pipelines. Under the hood, Harness bundles test files with Metro and executes them on connected devices, reporting results back to the CLI. It supports iOS, Android, and VegaOS. The library has already been integrated into react-native-mmkv, where it caught two previously unnoticed bugs during its first PR. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [React native testing: A complete introductory guide](https://daily.dev/posts/react-native-testing-a-complete-introductory-guide-kxg9lfr2u) · Testim.io · 0 upvotes · 0 comments --- Tags: [#testing](https://daily.dev/tags/testing), [#react-native](https://daily.dev/tags/react-native), [#jest](https://daily.dev/tags/jest) [View this post on daily.dev](https://daily.dev/posts/react-native-harness-fast-real-device-testing-for-native-modules-hqorjhowy) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"React Native Harness: Fast, Real-Device Testing for Native Modules","url":"https://daily.dev/posts/react-native-harness-fast-real-device-testing-for-native-modules-hqorjhowy","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/react-native-harness-fast-real-device-testing-for-native-modules-hqorjhowy"},"datePublished":"2026-06-08T12:42:35.043Z","dateModified":"2026-06-09T12:57:45.684Z","description":"React Native Harness is a new testing framework from Callstack that fills the gap between Jest (fast but no native execution) and E2E tools like Detox or...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/fc210fd32b9f401b99bac98a46ece935?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/fc210fd32b9f401b99bac98a46ece935?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Callstack Blog","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Callstack Blog","logo":"https://media.daily.dev/image/upload/s--3qItoroi--/f_auto,q_auto/v1774179048/logos/callstack-blog?_a=BAMAMiWQ0","url":"https://daily.dev/sources/callstack-blog"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/react-native-harness-fast-real-device-testing-for-native-modules-hqorjhowy","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"testing,react-native,jest","timeRequired":"PT6M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Callstack Blog","item":"https://daily.dev/sources/callstack-blog"},{"@type":"ListItem","position":3,"name":"React Native Harness: Fast, Real-Device Testing for Native Modules"}]} ```