Add getPublicInstance to support TestRenderer createNodeMock

Author: iamdustan

src/renderers/shared/fiber/ReactFiberCommitWork.js

@@ -86,7 +86,11 @@ module.exports = function<T, P, I, TI, C, CX>(
   function attachRef(current : ?Fiber, finishedWork : Fiber, instance : any) {
     const ref = finishedWork.ref;
     if (ref && (!current || current.ref !== ref)) {
-      ref(instance);
+      if (typeof config.getPublicInstance === 'function') {
+        ref(config.getPublicInstance(instance));
+      } else {
+        ref(instance);
+      }
     }
   }
 

src/renderers/shared/fiber/ReactFiberReconciler.js

@@ -47,6 +47,7 @@ export type HostConfig<T, P, I, TI, C, CX> = {
 
   getRootHostContext(rootContainerInstance : C) : CX,
   getChildHostContext(parentHostContext : CX, type : T) : CX,
+  getPublicInstance(instance : I) : I | any,
 
   createInstance(type : T, props : P, rootContainerInstance : C, hostContext : CX, internalInstanceHandle : OpaqueNode) : I,
   appendInitialChild(parentInstance : I, child : I | TI) : void,

src/renderers/testing/fiber/ReactTestFiberRenderer.js

@@ -229,6 +229,12 @@ var TestRenderer = ReactFiberReconciler({
   scheduleDeferredCallback: window.requestIdleCallback,
 
   useSyncScheduling: true,
+
+  getPublicInstance(ref) {
+    const createNodeMock = ref.rootContainerInstance.createNodeMock;
+    return createNodeMock(ref);
+  },
+
 });
 
 var defaultTestOptions = {