From 2307137b5275b41f6efe1c7f8720bbaa64136627 Mon Sep 17 00:00:00 2001
From: Khafra <42794878+KhafraDev@users.noreply.github.com>
Date: Wed, 4 May 2022 02:48:06 -0400
Subject: [PATCH] fix(Request): URLSearchParams body w/ Headers obj (#1410)

---
 lib/fetch/request.js  |  4 ++--
 test/fetch/request.js | 22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/lib/fetch/request.js b/lib/fetch/request.js
index 24210e59044..37f7c0c969f 100644
--- a/lib/fetch/request.js
+++ b/lib/fetch/request.js
@@ -467,8 +467,8 @@ class Request {
       // not contain `Content-Type`, then append `Content-Type`/Content-Type to
       // this’s headers.
       if (contentType && !this[kHeaders].has('content-type')) {
-        this[kHeaders].append('content-type', contentType)
-        this[kState].headersList.append('content-type', contentType)
+        this[kHeaders].set('content-type', contentType)
+        this[kState].headersList.set('content-type', contentType)
       }
     }
 
diff --git a/test/fetch/request.js b/test/fetch/request.js
index 5c84f754150..e37b395258f 100644
--- a/test/fetch/request.js
+++ b/test/fetch/request.js
@@ -7,6 +7,7 @@ const {
   Request
 } = require('../../')
 const { kState } = require('../../lib/fetch/symbols.js')
+const { URLSearchParams } = require('url')
 
 test('arg validation', (t) => {
   // constructor
@@ -261,6 +262,27 @@ test('pre aborted signal cloned', t => {
   t.end()
 })
 
+test('URLSearchParams body with Headers object - issue #1407', async (t) => {
+  const body = new URLSearchParams({
+    abc: 123
+  })
+
+  const request = new Request(
+    'http://localhost',
+    {
+      method: 'POST',
+      body,
+      headers: {
+        Authorization: 'test'
+      }
+    }
+  )
+
+  t.equal(request.headers.get('content-type'), 'application/x-www-form-urlencoded;charset=UTF-8')
+  t.equal(request.headers.get('authorization'), 'test')
+  t.equal(await request.text(), 'abc=123')
+})
+
 test('post aborted signal cloned', t => {
   t.plan(2)