vitest.config.ts

import react from '@vitejs/plugin-react';
import { resolve } from 'node:path';
import { defineConfig } from 'vitest/config';

/**
 * Vitest configuration with a hard 100% coverage gate.
 *
 * Any code under `src` that is reachable in a happy-path environment must be
 * covered by tests. Genuinely-unreachable defensive code (e.g. SSR guards,
 * `process.exit()` paths) can be exempted with a `v8 ignore` annotation
 * accompanied by a one-line reason — never to silence the gate.
 *
 * The thresholds are enforced by CI, so a PR cannot merge while coverage
 * sits below 100% on the activated surface. Playwright e2e specs live in
 * `e2e/` and are outside the vitest scope.
 */
export default defineConfig({
  plugins: [react()],
  // Unit tests render components without Tailwind processing. Override PostCSS
  // with an empty inline config so Vite does not auto-load the project
  // `postcss.config.mjs`, whose Next.js plugin shorthand Vite cannot parse.
  css: {
    postcss: {
      plugins: [],
    },
  },
  test: {
    environment: 'jsdom',
    setupFiles: ['./vitest.setup.ts'],
    include: ['src/__tests__/**/*.test.{ts,tsx}'],
    coverage: {
      provider: 'v8',
      reporter: ['text', 'text-summary', 'html', 'lcov'],
      include: ['src/**/*.{ts,tsx}'],
      exclude: [
        'src/**/*.test.{ts,tsx}',
        'src/**/__tests__/**',
        'src/types/**', // type-only modules contribute no executable code
      ],
      thresholds: {
        lines: 100,
        branches: 100,
        functions: 100,
        statements: 100,
      },
      all: true,
    },
  },
  resolve: {
    alias: {
      '@': resolve(__dirname, 'src'),
    },
  },
});