proposal-system/web/vitest.config.ts

import { defineConfig } from 'vitest/config';
import react from '@vitejs/plugin-react';

export default defineConfig({
  plugins: [react()],
  test: {
    environment: 'jsdom',
    globals: true,
    setupFiles: ['./src/test/setup.ts'],
    include: ['src/**/*.test.{ts,tsx}'],
    server: {
      deps: {
        // MUI v9's ESM build (Transition.mjs) does a directory import of
        // react-transition-group/TransitionGroupContext, which Node's native
        // ESM loader can't resolve. Inline these so Vite resolves them.
        inline: [/@mui\/material/, 'react-transition-group'],
      },
    },
  },
});