From c3d0cc2cb45fd11bb7b610020909a17fa51e95a8 Mon Sep 17 00:00:00 2001
From: Janic Duplessis <janicduplessis@gmail.com>
Date: Mon, 22 May 2017 17:16:48 -0400
Subject: [PATCH] FlatList - Add dev validation of the object returned by
 getItemLayout

---
 Libraries/Lists/VirtualizedList.js | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Libraries/Lists/VirtualizedList.js b/Libraries/Lists/VirtualizedList.js
index 21ce56dc0e6163..45c67090641317 100644
--- a/Libraries/Lists/VirtualizedList.js
+++ b/Libraries/Lists/VirtualizedList.js
@@ -13,6 +13,7 @@
 
 const Batchinator = require('Batchinator');
 const FillRateHelper = require('FillRateHelper');
+const PropTypes = require('prop-types');
 const React = require('React');
 const ReactNative = require('ReactNative');
 const RefreshControl = require('RefreshControl');
@@ -841,6 +842,19 @@ class VirtualizedList extends React.PureComponent<OptionalProps, Props, State> {
     if (!frame || frame.index !== index) {
       if (getItemLayout) {
         frame = getItemLayout(data, index);
+        if (__DEV__) {
+          const frameType = PropTypes.shape({
+            length: PropTypes.number.isRequired,
+            offset: PropTypes.number.isRequired,
+            index: PropTypes.number.isRequired,
+          }).isRequired;
+          PropTypes.checkPropTypes(
+            {frame: frameType},
+            {frame},
+            'frame',
+            'VirtualizedList.getItemLayout'
+          );
+        }
       }
     }
     return frame;