test: migrate util.js to ESM

- Changed all instances of loading the utility functions from 'util.js' to 'util.mjs' across various test files.
- Removed the old 'util.js' file and created a new 'util.mjs' file implementing the same functionality using ES module syntax.
- Updated paths and imports in test files to ensure compatibility with the new module format.

Author: toyobayashi

packages/test/arg/arg.test.js

@@ -1,6 +1,6 @@
 'use strict'
 const assert = require('assert')
-const { load } = require('../util')
+const { load } = require('../util.mjs')
 
 module.exports = load('arg').then((addon) => {
   assert.strictEqual(addon.add(3, 5), 8)

packages/test/array/array.test.js

@@ -1,6 +1,6 @@
 'use strict'
 const assert = require('assert')
-const { load } = require('../util')
+const { load } = require('../util.mjs')
 
 // eslint-disable-next-line camelcase
 module.exports = load('array').then(test_array => {

packages/test/async/async-wasi.test.browser.js

@@ -0,0 +1,83 @@
+/* eslint-disable no-undef */
+/* eslint-disable camelcase */
+
+import { test } from 'vitest'
+import assert from 'assert'
+
+console.log(assert)
+
+test('async-wasi', async function main () {
+  const init = async function () {
+    const { WASI } = await import('../../../node_modules/@tybys/wasm-util/dist/wasm-util.esm.js')
+    const { createNapiModule, loadNapiModule } = await import('../../core/dist/emnapi-core.js')
+    const { getDefaultContext } = await import('../../runtime/dist/emnapi.js')
+    const wasi = new WASI()
+    const napiModule = createNapiModule({
+      context: getDefaultContext(),
+      reuseWorker: {
+        size: 4
+      },
+      waitThreadStart: typeof window === 'undefined' ? 1000 : false,
+      onCreateWorker () {
+        return new Worker(new URL('../worker.mjs', import.meta.url), { type: 'module' })
+      },
+    })
+    const wasmMemory = new WebAssembly.Memory({
+      initial: 16777216 / 65536,
+      maximum: 2147483648 / 65536,
+      shared: true
+    })
+
+    const p = new Promise((resolve, reject) => {
+      loadNapiModule(napiModule, '../.build/wasm32-wasi-threads/Debug/async.wasm', {
+        wasi,
+        overwriteImports (importObject) {
+          importObject.env.memory = wasmMemory
+        }
+      }).then(() => {
+        resolve(napiModule.exports)
+      }).catch(reject)
+    })
+    p.Module = napiModule
+    return p
+  }
+  const test_async = await init()
+
+  await new Promise((resolve) => {
+    // Successful async execution and completion callback.
+    test_async.Test(5, {}, function (err, val) {
+      console.log('test_async.Test(5, {}, callback)')
+      assert.strictEqual(err, null)
+      assert.strictEqual(val, 10)
+      resolve()
+    })
+  })
+
+  await new Promise((resolve) => {
+    // Async work item cancellation with callback.
+    test_async.TestCancel(() => {
+      console.log('test_async.TestCancel(callback)')
+      resolve()
+    })
+  })
+
+  const iterations = 500
+  let x = 0
+  const workDone = (status) => {
+    assert.strictEqual(status, 0)
+    if (++x < iterations) {
+      setTimeout(() => test_async.DoRepeatedWork(workDone))
+    } else {
+      console.log(x)
+    }
+  }
+  test_async.DoRepeatedWork(workDone)
+
+  await new Promise((resolve) => {
+    setTimeout(resolve, 3000)
+  })
+
+  if (typeof postMessage === 'function') {
+     postMessage('done')
+  }
+})

packages/test/async/async.test.js

@@ -1,6 +1,6 @@
 /* eslint-disable camelcase */
 'use strict'
-const { load } = require('../util')
+const { load } = require('../util.mjs')
 const main = require('./main')
 
 module.exports = main(load('async'), __filename)

packages/test/async/async_hooks.test.js

@@ -1,6 +1,6 @@
 /* eslint-disable camelcase */
 'use strict'
-const { load } = require('../util')
+const { load } = require('../util.mjs')
 const common = require('../common')
 const assert = require('assert')
 const async_hooks = require('async_hooks')

packages/test/async/async_st.test.js

@@ -1,6 +1,6 @@
 /* eslint-disable camelcase */
 'use strict'
-const { load } = require('../util')
+const { load } = require('../util.mjs')
 const main = require('./main')
 
 const RUNTIME_UV_THREADPOOL_SIZE = ('UV_THREADPOOL_SIZE' in process.env) ? Number(process.env.UV_THREADPOOL_SIZE) : 4

packages/test/async_cleanup_hook/async_cleanup_hook.test.js

@@ -1,11 +1,11 @@
 'use strict'
 const common = require('../common')
 const { Worker } = require('worker_threads')
-const { load } = require('../util')
+const { load } = require('../util.mjs')
 
 module.exports = new Promise((resolve, reject) => {
   const w = new Worker(`
-    const { load } = require(${JSON.stringify(require.resolve('../util.js'))})
+    const { load } = require(${JSON.stringify(require.resolve('../util.mjs'))})
     load('async_cleanup_hook')
   `, {
     eval: true,

packages/test/async_context/ac.test.js

@@ -4,7 +4,7 @@
 
 const assert = require('assert')
 const async_hooks = require('async_hooks')
-const { load } = require('../util')
+const { load } = require('../util.mjs')
 
 module.exports = load('async_context', { nodeBinding: require('@emnapi/node-binding') }).then(binding => {
   const {

packages/test/async_context/gcable-callback.test.js

@@ -4,7 +4,7 @@
 
 const assert = require('assert')
 const async_hooks = require('async_hooks')
-const { load } = require('../util')
+const { load } = require('../util.mjs')
 
 module.exports = load('async_context', { nodeBinding: require('@emnapi/node-binding') }).then(binding => {
   return new Promise((resolve, reject) => {

packages/test/async_context/gcable.test.js

@@ -6,7 +6,7 @@ const assert = require('assert')
 const async_hooks = require('async_hooks')
 const common = require('../common')
 
-const { load } = require('../util')
+const { load } = require('../util.mjs')
 
 module.exports = load('async_context', { nodeBinding: require('@emnapi/node-binding') }).then(binding => {
   const { createAsyncResource } = binding