import { defineConfig, mergeConfig } from 'vitest/config';
import { playwright } from '@vitest/browser-playwright';

import viteConfig from './vite.config.js';

/**
 * Vitest configuration.
 *
 * Tests run in a real Chromium rather than a DOM emulation. Shadow DOM,
 * adopted stylesheets, `:focus-visible` and custom element upgrade timing are
 * exactly the things a component test needs to exercise, and they are also
 * the things jsdom/happy-dom approximate least well.
 *
 * The Vite config is merged in rather than duplicated so the TypeScript
 * decorator settings used to build the app are the same ones used to compile
 * the tests. Divergence there produces failures that are very hard to read.
 */
export default mergeConfig(
  viteConfig,
  defineConfig({
    test: {
      include: ['src/**/*.test.ts'],
      browser: {
        enabled: true,
        provider: playwright(),
        headless: true,
        instances: [{ browser: 'chromium' }],
      },
    },
  }),
);