From 89c7a2422b3627c66ad31cf50d7424c6bd231f23 Mon Sep 17 00:00:00 2001
From: Akira Sudoh <asudoh@gmail.com>
Date: Tue, 24 Dec 2019 07:51:44 +0900
Subject: [PATCH] fix(FileUploaderDropContainer): fix NPE selecting file

Fixes #4899.
---
 .../FileUploader/FileUploader-test.js         | 22 ++++++++++++++++++-
 .../FileUploader/FileUploaderDropContainer.js |  2 +-
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/packages/react/src/components/FileUploader/FileUploader-test.js b/packages/react/src/components/FileUploader/FileUploader-test.js
index b5ef7ed38c97..82eba4444e91 100644
--- a/packages/react/src/components/FileUploader/FileUploader-test.js
+++ b/packages/react/src/components/FileUploader/FileUploader-test.js
@@ -255,7 +255,13 @@ describe('FileUploader', () => {
 });
 
 describe('FileUploaderDropContainer', () => {
-  const dropContainer = <FileUploaderDropContainer className="extra-class" />;
+  const onAddFiles = jest.fn();
+  const dropContainer = (
+    <FileUploaderDropContainer
+      className="extra-class"
+      onAddFiles={onAddFiles}
+    />
+  );
   const mountWrapper = mount(dropContainer);
 
   describe('Renders as expected with default props', () => {
@@ -293,6 +299,20 @@ describe('FileUploaderDropContainer', () => {
 
       expect(evt.target.value).toEqual(null);
     });
+
+    it('does the right thing', () => {
+      const fileFoo = new File(['foo'], 'foo.txt', { type: 'text/plain' });
+      const fileBar = new File(['bar'], 'bar.txt', { type: 'text/plain' });
+      const mockFiles = [fileFoo, fileBar];
+      const input = mountWrapper.find(`.${prefix}--file-input`);
+      const evt = { target: { files: mockFiles } };
+      input.simulate('change', evt);
+      expect(onAddFiles).toHaveBeenCalledTimes(1);
+      expect(onAddFiles.mock.calls[0][0].target.files).toEqual([
+        fileFoo,
+        fileBar,
+      ]);
+    });
   });
 
   describe('Unique id props', () => {
diff --git a/packages/react/src/components/FileUploader/FileUploaderDropContainer.js b/packages/react/src/components/FileUploader/FileUploaderDropContainer.js
index 22c0b2b25921..17410bb84b9d 100644
--- a/packages/react/src/components/FileUploader/FileUploaderDropContainer.js
+++ b/packages/react/src/components/FileUploader/FileUploaderDropContainer.js
@@ -43,8 +43,8 @@ export default function FileUploaderDropContainer(props) {
    * @param {Event} evt - Event object, used to get the list of files added
    */
   const validateFiles = evt => {
-    const transferredFiles = [...evt.dataTransfer.files];
     if (evt.type === 'drop') {
+      const transferredFiles = [...evt.dataTransfer.files];
       if (!accept.length) {
         return transferredFiles;
       }