From 3fd6484fbfe4319c464ff9b1735a1158834f9246 Mon Sep 17 00:00:00 2001
From: Keyan Zhang <keyanz@fb.com>
Date: Tue, 2 Aug 2016 14:38:02 -0700
Subject: [PATCH 1/2] corrected ReactChildrenMutationWarningHook's name

---
 .../shared/hooks/ReactChildrenMutationWarningHook.js          | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/renderers/shared/hooks/ReactChildrenMutationWarningHook.js b/src/renderers/shared/hooks/ReactChildrenMutationWarningHook.js
index fccc1538545ad..ee913ccfcd260 100644
--- a/src/renderers/shared/hooks/ReactChildrenMutationWarningHook.js
+++ b/src/renderers/shared/hooks/ReactChildrenMutationWarningHook.js
@@ -46,7 +46,7 @@ function handleElement(debugID, element) {
   );
 }
 
-var ReactDOMUnknownPropertyHook = {
+var ReactChildrenMutationWarningHook = {
   onBeforeMountComponent(debugID, element) {
     elements[debugID] = element;
   },
@@ -63,4 +63,4 @@ var ReactDOMUnknownPropertyHook = {
   },
 };
 
-module.exports = ReactDOMUnknownPropertyHook;
+module.exports = ReactChildrenMutationWarningHook;

From 188a06856147056cc7ac359eca9e5f1ab604f931 Mon Sep 17 00:00:00 2001
From: Keyan Zhang <keyanz@fb.com>
Date: Tue, 2 Aug 2016 17:04:14 -0700
Subject: [PATCH 2/2] changed `onComponentHasMounted` to `onMountComponent`

and get element from `ReactComponentTreeHook` instead of keeping an internal store
---
 .../__tests__/ReactServerRendering-test.js    | 34 +++++++++++++++++++
 .../hooks/ReactChildrenMutationWarningHook.js | 16 ++-------
 2 files changed, 37 insertions(+), 13 deletions(-)

diff --git a/src/renderers/dom/server/__tests__/ReactServerRendering-test.js b/src/renderers/dom/server/__tests__/ReactServerRendering-test.js
index e552678c8a6c4..1c3753028a3e6 100644
--- a/src/renderers/dom/server/__tests__/ReactServerRendering-test.js
+++ b/src/renderers/dom/server/__tests__/ReactServerRendering-test.js
@@ -538,4 +538,38 @@ describe('ReactServerRendering', function() {
     var markup = ReactServerRendering.renderToStaticMarkup(<Baz />);
     expect(markup).toBe('<div></div>');
   });
+
+  it('warns when children are mutated before render', function() {
+    function normalizeCodeLocInfo(str) {
+      return str.replace(/\(at .+?:\d+\)/g, '(at **)');
+    }
+
+    spyOn(console, 'error');
+    var children = [<span key={0} />, <span key={1} />, <span key={2} />];
+    var element = <div>{children}</div>;
+    children[1] = <p key={1} />; // Mutation is illegal
+    ReactServerRendering.renderToString(element);
+    expect(console.error.calls.count()).toBe(1);
+    expect(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
+      'Warning: Component\'s children should not be mutated.\n    in div (at **)'
+    );
+  });
+
+  it('should warn when children are mutated', function() {
+    function normalizeCodeLocInfo(str) {
+      return str.replace(/\(at .+?:\d+\)/g, '(at **)');
+    }
+
+    spyOn(console, 'error');
+    var children = [<span key={0} />, <span key={1} />, <span key={2} />];
+    function Wrapper(props) {
+      props.children[1] = <p key={1} />; // Mutation is illegal
+      return <div>{props.children}</div>;
+    }
+    ReactServerRendering.renderToString(<Wrapper>{children}</Wrapper>);
+    expect(console.error.calls.count()).toBe(1);
+    expect(normalizeCodeLocInfo(console.error.calls.argsFor(0)[0])).toBe(
+      'Warning: Component\'s children should not be mutated.\n    in Wrapper (at **)'
+    );
+  });
 });
diff --git a/src/renderers/shared/hooks/ReactChildrenMutationWarningHook.js b/src/renderers/shared/hooks/ReactChildrenMutationWarningHook.js
index ee913ccfcd260..e8d063d58a9a6 100644
--- a/src/renderers/shared/hooks/ReactChildrenMutationWarningHook.js
+++ b/src/renderers/shared/hooks/ReactChildrenMutationWarningHook.js
@@ -15,8 +15,6 @@ var ReactComponentTreeHook = require('ReactComponentTreeHook');
 
 var warning = require('warning');
 
-var elements = {};
-
 function handleElement(debugID, element) {
   if (element == null) {
     return;
@@ -47,19 +45,11 @@ function handleElement(debugID, element) {
 }
 
 var ReactChildrenMutationWarningHook = {
-  onBeforeMountComponent(debugID, element) {
-    elements[debugID] = element;
-  },
-  onBeforeUpdateComponent(debugID, element) {
-    elements[debugID] = element;
-  },
-  onComponentHasMounted(debugID) {
-    handleElement(debugID, elements[debugID]);
-    delete elements[debugID];
+  onMountComponent(debugID) {
+    handleElement(debugID, ReactComponentTreeHook.getElement(debugID));
   },
   onComponentHasUpdated(debugID) {
-    handleElement(debugID, elements[debugID]);
-    delete elements[debugID];
+    handleElement(debugID, ReactComponentTreeHook.getElement(debugID));
   },
 };