chore(test): cover issue 5014 (#5015)

Author: rozzilla

test/utils/esm-wrapper.mjs

@@ -1,6 +1,6 @@
 import { createServer } from 'node:http'
 import { test, after } from 'node:test'
-import {
+import undici, {
   Agent,
   Client,
   errors,
@@ -99,3 +99,29 @@ test('named exports', (t) => {
   t.assert.strictEqual(typeof setGlobalDispatcher, 'function')
   t.assert.strictEqual(typeof getGlobalDispatcher, 'function')
 })
+
+test('default import top-level request works with opts.dispatcher', async (t) => {
+  t.plan(4)
+
+  const server = createServer({ joinDuplicateHeaders: true }, (req, res) => {
+    t.assert.strictEqual(req.method, 'GET')
+    t.assert.strictEqual(req.url, '/')
+    res.end('ok')
+  })
+
+  await new Promise((resolve) => server.listen(0, resolve))
+
+  const dispatcher = new undici.Agent({ allowH2: true })
+
+  t.after(async () => {
+    await dispatcher.close()
+    await new Promise((resolve) => server.close(resolve))
+  })
+
+  const { statusCode, body } = await undici.request(`http://127.0.0.1:${server.address().port}`, {
+    dispatcher
+  })
+
+  t.assert.strictEqual(statusCode, 200)
+  t.assert.strictEqual(await body.text(), 'ok')
+})