--coverage reports 0% in create-react-native-library setups

[mfazekas]

Describe the bug

When running harness tests with --coverage in a create-react-native-library project, coverage always reports 0% for library source files even though tests pass and execute the code.

System Info

% npx react-native info               
info Fetching system and libraries information...
System:
  OS: macOS 15.7.3
  CPU: (12) arm64 Apple M2 Max
  Memory: 200.47 MB / 32.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 22.16.0
    path: /Users/boga/.nvm/versions/node/v22.16.0/bin/node
  Yarn:
    version: 3.6.1
    path: /Users/boga/.local/bin/yarn
  npm:
    version: 11.5.2
    path: /Users/boga/.nvm/versions/node/v22.16.0/bin/npm
  Watchman:
    version: 2025.06.30.00
    path: /opt/homebrew/bin/watchman
Managers:
  CocoaPods:
    version: 1.16.2
    path: /Users/boga/.rbenv/shims/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 24.5
      - iOS 18.5
      - macOS 15.5
      - tvOS 18.5
      - visionOS 2.5
      - watchOS 11.5
  Android SDK: Not Found
IDEs:
  Android Studio: 2025.1 AI-251.27812.49.2514.14217341
  Xcode:
    version: 16.4/16F6
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 20.0.1
    path: /usr/bin/javac
  Ruby:
    version: 2.7.8
    path: /Users/boga/.rbenv/shims/ruby
npmPackages:
  "@react-native-community/cli":
    installed: 18.0.0
    wanted: 18.0.0
  react:
    installed: 19.0.0
    wanted: 19.0.0
  react-native:
    installed: 0.79.2
    wanted: 0.79.2
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: true
iOS:
  hermesEnabled: true
  newArchEnabled: true

React Native Harness Version

1.0.0-canary.1766225407244

Reproduction

https://github.com/rive-app/rive-nitro-react-native/tree/repro/harness-coverage-zero

Steps to reproduce

git clone https://github.com/rive-app/rive-nitro-react-native
cd rive-nitro-react-native
git checkout repro/harness-coverage-zero
yarn install
cd example/ios
pod install
cd ..
yarn test:harness:ios --coverage

Shows 0% coverage

[mfazekas]

Workaround: You can set NYC_CWD environment variable as a temporary fix:

NYC_CWD=.. yarn test:harness:ios --coverage

This tells istanbul to use the parent directory as its root, allowing it to instrument files in ../src/.

[V3RON]

Thanks for the PR! I'll let you know when it's released.

[V3RON]

It's out in the latest release 🎉