From 5c9224145ee0fe2de65e98d2540ccc0f004b1b00 Mon Sep 17 00:00:00 2001
From: Ben Alpert <spicyjalapeno@gmail.com>
Date: Wed, 7 May 2014 09:54:23 -0300
Subject: [PATCH] ReactTransitionGroup: Fix moving from falsey child

See http://stackoverflow.com/q/23510413/49485.

Test Plan: grunt fasttest
---
 src/addons/transitions/ReactTransitionGroup.js |  6 ++++--
 .../__tests__/ReactCSSTransitionGroup-test.js  | 18 ++++++++++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/addons/transitions/ReactTransitionGroup.js b/src/addons/transitions/ReactTransitionGroup.js
index f77f63a1cd..7614bb7605 100644
--- a/src/addons/transitions/ReactTransitionGroup.js
+++ b/src/addons/transitions/ReactTransitionGroup.js
@@ -62,14 +62,16 @@ var ReactTransitionGroup = React.createClass({
 
     for (key in nextChildMapping) {
       var hasPrev = prevChildMapping && prevChildMapping.hasOwnProperty(key);
-      if (!hasPrev && !this.currentlyTransitioningKeys[key]) {
+      if (nextChildMapping[key] && !hasPrev &&
+          !this.currentlyTransitioningKeys[key]) {
         this.keysToEnter.push(key);
       }
     }
 
     for (key in prevChildMapping) {
       var hasNext = nextChildMapping && nextChildMapping.hasOwnProperty(key);
-      if (!hasNext && !this.currentlyTransitioningKeys[key]) {
+      if (prevChildMapping[key] && !hasNext &&
+          !this.currentlyTransitioningKeys[key]) {
         this.keysToLeave.push(key);
       }
     }
diff --git a/src/addons/transitions/__tests__/ReactCSSTransitionGroup-test.js b/src/addons/transitions/__tests__/ReactCSSTransitionGroup-test.js
index ef06239501..1508927bcb 100644
--- a/src/addons/transitions/__tests__/ReactCSSTransitionGroup-test.js
+++ b/src/addons/transitions/__tests__/ReactCSSTransitionGroup-test.js
@@ -163,4 +163,22 @@ describe('ReactCSSTransitionGroup', function() {
     expect(a.getDOMNode().childNodes[0].id).toBe('one');
   });
 
+  it('should transition from false to one', function() {
+    var a = React.renderComponent(
+      <ReactCSSTransitionGroup transitionName="yolo">
+        {false}
+      </ReactCSSTransitionGroup>,
+      container
+    );
+    expect(a.getDOMNode().childNodes.length).toBe(0);
+    React.renderComponent(
+      <ReactCSSTransitionGroup transitionName="yolo">
+        <span key="one" id="one" />
+      </ReactCSSTransitionGroup>,
+      container
+    );
+    expect(a.getDOMNode().childNodes.length).toBe(1);
+    expect(a.getDOMNode().childNodes[0].id).toBe('one');
+  });
+
 });