Fix context getting (facebook#8407)

Author: sophiebits

scripts/fiber/tests-passing.txt

@@ -49,6 +49,8 @@ src/addons/__tests__/renderSubtreeIntoContainer-test.js
 * should update context if it changes due to setState
 * should update context if it changes due to re-render
 * should render portal with non-context-provider parent
+* should get context through non-context-provider parent
+* should get context through middle non-context-provider layer
 
 src/addons/__tests__/update-test.js
 * pushes

src/addons/__tests__/renderSubtreeIntoContainer-test.js

@@ -215,4 +215,86 @@ describe('renderSubtreeIntoContainer', () => {
     expect(portal.firstChild.innerHTML).toBe('hello');
   });
 
+  it('should get context through non-context-provider parent', () => {
+    var container = document.createElement('div');
+    document.body.appendChild(container);
+    var portal = document.createElement('div');
+
+    class Parent extends React.Component {
+      render() {
+        return <Middle />;
+      }
+      getChildContext() {
+        return {value: this.props.value};
+      }
+      static childContextTypes = {
+        value: React.PropTypes.string.isRequired,
+      };
+    }
+
+    class Middle extends React.Component {
+      render() {
+        return null;
+      }
+      componentDidMount() {
+        renderSubtreeIntoContainer(this, <Child />, portal);
+      }
+    }
+
+    class Child extends React.Component {
+      static contextTypes = {
+        value: React.PropTypes.string.isRequired,
+      };
+      render() {
+        return <div>{this.context.value}</div>;
+      }
+    }
+
+    ReactDOM.render(<Parent value="foo" />, container);
+    expect(portal.textContent).toBe('foo');
+  });
+
+  it('should get context through middle non-context-provider layer', () => {
+    var container = document.createElement('div');
+    document.body.appendChild(container);
+    var portal1 = document.createElement('div');
+    var portal2 = document.createElement('div');
+
+    class Parent extends React.Component {
+      render() {
+        return null;
+      }
+      getChildContext() {
+        return {value: this.props.value};
+      }
+      componentDidMount() {
+        renderSubtreeIntoContainer(this, <Middle />, portal1);
+      }
+      static childContextTypes = {
+        value: React.PropTypes.string.isRequired,
+      };
+    }
+
+    class Middle extends React.Component {
+      render() {
+        return null;
+      }
+      componentDidMount() {
+        renderSubtreeIntoContainer(this, <Child />, portal2);
+      }
+    }
+
+    class Child extends React.Component {
+      static contextTypes = {
+        value: React.PropTypes.string.isRequired,
+      };
+      render() {
+        return <div>{this.context.value}</div>;
+      }
+    }
+
+    ReactDOM.render(<Parent value="foo" />, container);
+    expect(portal2.textContent).toBe('foo');
+  });
+
 });

src/renderers/shared/fiber/ReactFiberContext.js

@@ -22,6 +22,7 @@ var {
 } = require('ReactFiberTreeReflection');
 var {
   ClassComponent,
+  HostContainer,
 } = require('ReactTypeOfWork');
 
 if (__DEV__) {
@@ -137,12 +138,14 @@ exports.findCurrentUnmaskedContext = function(fiber: Fiber) : Object {
     'Expected subtree parent to be a mounted class component'
   );
 
-  let node : ?Fiber = parent;
-  while (node) {
-    if (isContextProvider(fiber)) {
-      return fiber.stateNode.__reactInternalMemoizedMergedChildContext;
+  let node : Fiber = fiber;
+  while (node.tag !== HostContainer) {
+    if (isContextProvider(node)) {
+      return node.stateNode.__reactInternalMemoizedMergedChildContext;
     }
-    node = node.return;
+    const parent = node.return;
+    invariant(parent, 'Found unexpected detached subtree parent');
+    node = parent;
   }
-  return emptyObject;
+  return node.stateNode.context;
 };