fix: set content-length when using FormData body w/ request (#2066)

* fix: set content-length when using FormData body w/ request

* import FormData

lib/core/request.js

@@ -182,6 +182,7 @@ class Request {
         this.headers += `content-type: ${contentType}\r\n`
       }
       this.body = bodyStream.stream
+      this.contentLength = bodyStream.length
     } else if (util.isBlobLike(body) && this.contentType == null && body.type) {
       this.contentType = body.type
       this.headers += `content-type: ${body.type}\r\n`

test/issue-2065.js

@@ -0,0 +1,30 @@
+'use strict'
+
+const { test, skip } = require('tap')
+const { nodeMajor, nodeMinor } = require('../lib/core/util')
+const { createServer } = require('http')
+const { once } = require('events')
+const { File, FormData, request } = require('..')
+
+if (nodeMajor < 16 || (nodeMajor === 16 && nodeMinor < 8)) {
+  skip('FormData is not available in node < v16.8.0')
+  process.exit()
+}
+
+test('undici.request with a FormData body should set content-length header', async (t) => {
+  const server = createServer((req, res) => {
+    t.ok(req.headers['content-length'])
+    res.end()
+  }).listen(0)
+
+  t.teardown(server.close.bind(server))
+  await once(server, 'listening')
+
+  const body = new FormData()
+  body.set('file', new File(['abc'], 'abc.txt'))
+
+  await request(`http://localhost:${server.address().port}`, {
+    method: 'POST',
+    body
+  })
+})