From ea69047503bda3a8e4a42a406fabfd1c03b1a182 Mon Sep 17 00:00:00 2001
From: Robert Nagy <ronagy@icloud.com>
Date: Tue, 21 Feb 2023 16:41:11 +0100
Subject: [PATCH] fix: improve isFormDataLike compat

Fixes: https://github.com/nodejs/undici/issues/1952
---
 lib/core/util.js       | 25 +++++++++++--------------
 test/fetch/formdata.js |  4 ++++
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/lib/core/util.js b/lib/core/util.js
index ef9b4570dcd..334bc26c776 100644
--- a/lib/core/util.js
+++ b/lib/core/util.js
@@ -375,20 +375,17 @@ function ReadableStreamFrom (iterable) {
 
 // The chunk should be a FormData instance and contains
 // all the required methods.
-function isFormDataLike (chunk) {
-  return (chunk &&
-    chunk.constructor && chunk.constructor.name === 'FormData' &&
-    typeof chunk === 'object' &&
-      (typeof chunk.append === 'function' &&
-        typeof chunk.delete === 'function' &&
-        typeof chunk.get === 'function' &&
-        typeof chunk.getAll === 'function' &&
-        typeof chunk.has === 'function' &&
-        typeof chunk.set === 'function' &&
-        typeof chunk.entries === 'function' &&
-        typeof chunk.keys === 'function' &&
-        typeof chunk.values === 'function' &&
-        typeof chunk.forEach === 'function')
+function isFormDataLike (object) {
+  return (
+    object &&
+    typeof object === 'object' &&
+    typeof object.append === 'function' &&
+    typeof object.delete === 'function' &&
+    typeof object.get === 'function' &&
+    typeof object.getAll === 'function' &&
+    typeof object.has === 'function' &&
+    typeof object.set === 'function' &&
+    object[Symbol.toStringTag] === 'FormData'
   )
 }
 
diff --git a/test/fetch/formdata.js b/test/fetch/formdata.js
index 156c11fb77d..fed95bfb3da 100644
--- a/test/fetch/formdata.js
+++ b/test/fetch/formdata.js
@@ -349,6 +349,10 @@ test('FormData should be compatible with third-party libraries', (t) => {
       this.data = []
     }
 
+    get [Symbol.toStringTag] () {
+      return 'FormData'
+    }
+
     append () {}
     delete () {}
     get () {}