build.js

import fs from 'fs/promises'
import path from 'path'
import { fileURLToPath } from 'url'
import { build } from 'esbuild'

const __filename = fileURLToPath(import.meta.url)
const __dirname = path.dirname(__filename)

export async function* walk(rootPath) {
  for (const fileName of await fs.readdir(rootPath)) {
    const filePath = path.join(rootPath, fileName)
    if ((await fs.stat(filePath)).isDirectory()) {
      yield* walk(filePath)
    } else {
      yield filePath
    }
  }
}

const src = path.join(__dirname, 'src', 'index.ts')
const entryPoints = [src]
if (process.argv[2] === 'test') {
  for await (const test of walk(path.join(__dirname, 'test'))) {
    if (test.endsWith('.spec.ts')) entryPoints.push(test)
  }
}

try {
  await build({
    bundle: true,
    sourcemap: true,
    format: 'esm',
    outdir: path.join(__dirname, 'dist'),
    outbase: __dirname,
    outExtension: { '.js': '.mjs' },
    entryPoints,
    external: ['jest', '@jest'],
  })
} catch {
  process.exitCode = 1
}