vitest/test/core/vitest.config.ts

import { basename, dirname, join, resolve } from 'pathe'
import { defineConfig } from 'vite'

export default defineConfig({
  plugins: [
    {
      name: 'example',
      resolveId(source) {
        if (source === 'virtual-module')
          return source
      },
      load(id) {
        if (id === 'virtual-module') {
          return `
            export const value = 'original';
          `
        }
      },
    },
  ],
  define: {
    'import.meta.env.TEST_NAME': '"hello world"',
    'process.env.HELLO_PROCESS': '"hello process"',
    // can reassign
    '__DEFINE__': '"defined"',
    '__JSON__': JSON.stringify({ hello: 'world' }),
    // edge cases
    // should not be available for reassigning as __MODE__ = 'test2'
    // but can reassign with process.env.MODE = 'test2'
    '__MODE__': 'process.env.MODE',
    'SOME.VARIABLE': '"variable"',
    'SOME.SOME.VARIABLE': '"nested variable"',
  },
  resolve: {
    alias: [
      { find: '@', replacement: resolve(__dirname, 'src') },
    ],
  },
  test: {
    testTimeout: 2000,
    setupFiles: [
      './test/setup.ts',
    ],
    testNamePattern: '^((?!does not include test that).)*$',
    coverage: {
      reporter: ['text', 'html'],
    },
    resolveSnapshotPath: (path, extension) => {
      if (path.includes('moved-snapshot'))
        return path + extension
      return join(dirname(path), '__snapshots__', `${basename(path)}${extension}`)
    },
  },
})