@rstest/browser-react

React component testing support for Rstest browser mode. Provides render, renderHook, cleanup, and act utilities for testing React components in a real browser environment.

Do

• Support React 17, 18, and 19 — ensure code works across all versions
• Use act() for all render/unmount/state update operations
• Keep this package focused on React rendering lifecycle only
• Use JSDoc comments for public API functions

Don't

• Don't add DOM query utilities (users should use @testing-library/dom)
• Don't add dependencies beyond React peer deps
• Don't break compatibility with older React versions without discussion
• Don't use React version-specific APIs without fallbacks

Commands

# Build
pnpm --filter @rstest/browser-react build
pnpm --filter @rstest/browser-react dev     # Watch mode

# Run tests
pnpm --filter @rstest/browser-react test

Project structure

• src/index.ts — Default entry with auto-cleanup via beforeEach
• src/pure.tsx — Core implementation (render, renderHook, cleanup, configure)
• src/act.ts — React act() wrapper with IS_REACT_ACT_ENVIRONMENT management

Good and bad examples

Handling React version differences

Good — use feature detection with fallback:

// src/act.ts
const _act = (React as Record<string, unknown>).act as
  | ((callback: () => unknown) => Promise<void>)
  | undefined;

export const act: ActFunction =
  typeof _act !== 'function'
    ? async (callback) => {
        await callback();
      } // React 17 fallback
    : async (callback) => {
        await _act(callback);
      }; // React 18+

Bad — assume specific React version:

import { act } from 'react'; // Breaks React 17