feat: UI testing API with queries and actions

[V3RON]

Description

Implement UI testing capabilities for React Native Harness, providing screen queries and user interaction utilities for native mobile testing.

This feature adds the @react-native-harness/ui package with:

• Screen queries: findByTestId, findAllByTestId, queryByTestId, queryAllByTestId, findByAccessibilityLabel, findAllByAccessibilityLabel, queryByAccessibilityLabel, queryAllByAccessibilityLabel
• User interactions: userEvent.press(), userEvent.pressAt(), userEvent.type()
• Screenshot capture: screen.screenshot() for visual regression testing
• TypeScript support with comprehensive type definitions

Context

This branch introduces native UI testing functionality to complement React Native Harness's existing native module testing capabilities. Unlike traditional React Testing Library approaches that focus on component trees, this implementation provides direct access to native UI elements through testIDs and accessibility labels, enabling:

• Real device testing: Query actual rendered UI elements on physical devices/emulators
• Native behavior validation: Test native module interactions and UI state changes
• Visual regression testing: Capture and compare screenshots of UI components
• Cross-platform compatibility: Unified API for both iOS and Android testing

The implementation includes:

• Native modules for iOS (HarnessUI.mm) and Android (HarnessUIModule.kt)
• TypeScript API layer with async/sync query methods

This feature bridges the gap between Jest's JavaScript-only testing and full native mobile testing, providing developers with familiar testing patterns while maintaining access to native platform capabilities.

[vercel]

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Project	Deployment	Review	Updated (UTC)
react-native-harness	Ready	Preview, Comment	Jan 15, 2026 7:52pm