switch on filename, add tests

lib/fetch/index.js

@@ -1344,7 +1344,7 @@ async function httpNetworkOrCacheFetch (
  // user agents should append `User-Agent`/default `User-Agent` value to
  // httpRequest’s header list.
  if (!httpRequest.headersList.contains('user-agent')) {
- httpRequest.headersList.append('user-agent', 'node')
+ httpRequest.headersList.append('user-agent', __filename.endsWith('index.js') ? 'undici' : 'node')
  }
 
  // 15. If httpRequest’s cache mode is "default" and httpRequest’s header

test/fetch/user-agent.js

@@ -0,0 +1,25 @@
+'use strict'
+
+const { test } = require('tap')
+const events = require('events')
+const http = require('http')
+const undici = require('../../')
+const nodeBuild = require('../../undici-fetch.js')
+
+test('user-agent defaults correctly', async (t) => {
+ const server = http.createServer((req, res) => {
+ res.end(JSON.stringify({ userAgentHeader: req.headers['user-agent'] }))
+ })
+ t.teardown(server.close.bind(server))
+
+ server.listen(0)
+ await events.once(server, 'listening')
+ const url = `http://localhost:${server.address().port}`
+ const [nodeBuildJSON, undiciJSON] = await Promise.all([
+ nodeBuild.fetch(url).then((body) => body.json()),
+ undici.fetch(url).then((body) => body.json())
+ ])
+
+ t.same(nodeBuildJSON.userAgentHeader, 'node')
+ t.same(undiciJSON.userAgentHeader, 'undici')
+})

test/mock-agent.js

@@ -2449,7 +2449,7 @@ test('MockAgent - using fetch yields a headers object in the reply callback', {
  accept: '*/*',
  'accept-language': '*',
  'sec-fetch-mode': 'cors',
- 'user-agent': 'node',
+ 'user-agent': 'undici',
  'accept-encoding': 'gzip, deflate'
  })
 

test/proxy-agent.js

@@ -389,7 +389,7 @@ test('ProxyAgent correctly sends headers when using fetch - #1355, #1623', { ski
  accept: '*/*',
  'accept-language': '*',
  'sec-fetch-mode': 'cors',
- 'user-agent': 'node',
+ 'user-agent': 'undici',
  'accept-encoding': 'gzip, deflate'
  }