Windows

    React Native Harness runs tests against a deployed React Native Windows app.

    Overview

    Unlike Android and iOS, where Harness boots an emulator or simulator, the Windows runner works with an app you have already deployed to the machine. Harness resolves the app by its package identity, launches it, and tracks its process for the duration of the run. Build and deploy the app with react-native run-windows before invoking Harness.

    Installation

    npm
    yarn
    pnpm
    bun
    deno
    npm install --save-dev @react-native-harness/platform-windows

    Configuration

    Import the Windows platform helper in your rn-harness.config.mjs:

    import { windowsPlatform } from '@react-native-harness/platform-windows';

export default {
  entryPoint: './index.js',
  appRegistryComponentName: 'MyApp',
  runners: [
    windowsPlatform({
      name: 'windows',
      // The Identity/@Name from windows/<App>/Package.appxmanifest
      packageName: 'MyApp',
    }),
  ],
};

    Options

    OptionTypeDefaultDescription
    namestring–Unique name for the runner.
    packageNamestring–The Identity/@Name from Package.appxmanifest. Harness looks the deployed package up with Get-AppxPackage -Name <packageName>.
    appIdstring'App'The Application/@Id from Package.appxmanifest. Combined with the package family name into the AUMID used to activate the app.
    processNamestringpackageNameThe app's process name (without .exe), used to detect whether it is still running.

    Finding the package identity

    Open windows/<YourApp>/Package.appxmanifest and look at the Identity and Application elements:

    <Identity Name="MyApp" ... />
...
<Applications>
  <Application Id="App" ... />
</Applications>

    Here packageName is MyApp and appId is App (the default).

    Deploying the app

    The Windows runner never builds — deploy the app first:

    npx react-native run-windows --arch x64 --no-launch --no-packager --logging

    --no-launch registers the MSIX package without starting it (Harness starts it), and --no-packager keeps run-windows from starting its own Metro server on the port Harness wants.

    Then run the tests:

    npx react-native-harness --harnessRunner windows

    Metro configuration

    Harness applies the same out-of-tree platform wiring that react-native start does (the react-native → react-native-windows resolver redirect and the Windows InitializeCore), so a plain metro.config.js works — you do not need to add a windows case to resolver.resolveRequest or serializer.getModulesRunBeforeMainModule yourself.

    Requirements

    • Windows 10 or 11.
    • The React Native Windows toolchain (Visual Studio with the C++ workload, the Windows SDK) to build the app.
    • The app deployed via react-native run-windows before the run.
    • The harness Metro server reachable at the app's bundle URL (http://localhost:8081 by default). An RNW Debug build points there out of the box.

    CI

    The official GitHub Action supports the windows runner. Run the job on a windows-* runner, deploy the app in an earlier step, then invoke the action without an app input — see Running in CI/CD.

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