From 33d8934477feb2826d4495ef90daafa07cba4069 Mon Sep 17 00:00:00 2001
From: John <johnjessewood@hotmail.com>
Date: Tue, 22 Dec 2020 20:57:50 +0000
Subject: [PATCH] fix: use a data transfewr object supplied by the event caller

---
 src/__tests__/events.js | 17 +++++++++++++++++
 src/events.js           |  5 ++++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/__tests__/events.js b/src/__tests__/events.js
index 5fc9d7fd..0ee5bb42 100644
--- a/src/__tests__/events.js
+++ b/src/__tests__/events.js
@@ -327,6 +327,23 @@ test('assigning the files property on dataTransfer', () => {
   expect(spy.mock.calls[0][0]).toHaveProperty('dataTransfer.files', [file])
 })
 
+test('uses the supplied data transfer instance if passed in by the caller', () => {
+  function FakeDataTransfer() {}
+
+  window.DataTransfer = FakeDataTransfer
+
+  const node = document.createElement('div')
+  const spy = jest.fn()
+  node.addEventListener('drop', spy)
+
+  const dataTransfer = new FakeDataTransfer()
+
+  fireEvent.drop(node, {dataTransfer})
+  expect(spy).toHaveBeenCalledTimes(1)
+  expect(spy.mock.calls[0][0].dataTransfer).toEqual(dataTransfer)
+  delete window.DataTransfer
+})
+
 test('assigns clipboardData properties', () => {
   const node = document.createElement('div')
   const spy = jest.fn()
diff --git a/src/events.js b/src/events.js
index 57446bf8..f3506105 100644
--- a/src/events.js
+++ b/src/events.js
@@ -69,7 +69,10 @@ function createEvent(
 
     if (typeof dataTransferValue === 'object') {
       /* istanbul ignore if  */
-      if (typeof window.DataTransfer === 'function') {
+      if (
+        typeof window.DataTransfer === 'function' &&
+        !(dataTransferValue instanceof window.DataTransfer)
+      ) {
         Object.defineProperty(event, dataTransferKey, {
           value: Object.getOwnPropertyNames(dataTransferValue).reduce(
             (acc, propName) => {