diff --git a/src/renderers/testing/ReactTestMount.js b/src/renderers/testing/ReactTestMount.js
index 74d3c72d5011e..a3f2e61aff76a 100644
--- a/src/renderers/testing/ReactTestMount.js
+++ b/src/renderers/testing/ReactTestMount.js
@@ -19,6 +19,7 @@ var ReactUpdates = require('ReactUpdates');
 var emptyObject = require('emptyObject');
 var getHostComponentFromComposite = require('getHostComponentFromComposite');
 var instantiateReactComponent = require('instantiateReactComponent');
+var invariant = require('invariant');
 
 /**
  * Temporary (?) hack so that we can store all top-level pending updates on
@@ -83,6 +84,48 @@ var ReactTestInstance = function(component) {
 ReactTestInstance.prototype.getInstance = function() {
   return this._component._renderedComponent.getPublicInstance();
 };
+ReactTestInstance.prototype.update = function(nextElement) {
+  invariant(
+    this._component,
+    "ReactTestRenderer: .update() can't be called after unmount."
+  );
+  var nextWrappedElement = new ReactElement(
+    TopLevelWrapper,
+    null,
+    null,
+    null,
+    null,
+    null,
+    nextElement
+  );
+  var component = this._component;
+  ReactUpdates.batchedUpdates(function() {
+    var transaction = ReactUpdates.ReactReconcileTransaction.getPooled(true);
+    transaction.perform(function() {
+      ReactReconciler.receiveComponent(
+        component,
+        nextWrappedElement,
+        transaction,
+        emptyObject
+      );
+    });
+    ReactUpdates.ReactReconcileTransaction.release(transaction);
+  });
+};
+ReactTestInstance.prototype.unmount = function(nextElement) {
+  var component = this._component;
+  ReactUpdates.batchedUpdates(function() {
+    var transaction = ReactUpdates.ReactReconcileTransaction.getPooled(true);
+    transaction.perform(function() {
+      ReactReconciler.unmountComponent(
+        component,
+        false
+      );
+    });
+    ReactUpdates.ReactReconcileTransaction.release(transaction);
+  });
+  this._component = null;
+};
 ReactTestInstance.prototype.toJSON = function() {
   var inst = getHostComponentFromComposite(this._component);
   return inst.toJSON();
@@ -92,7 +135,7 @@ ReactTestInstance.prototype.toJSON = function() {
  * As soon as `ReactMount` is refactored to not rely on the DOM, we can share
  * code between the two. For now, we'll hard code the ID logic.
  */
-var ReactHostMount = {
+var ReactTestMount = {
 
   render: function(
     nextElement: ReactElement
@@ -107,19 +150,6 @@ var ReactHostMount = {
       nextElement
     );
 
-    // var prevComponent = ReactHostMount._instancesByContainerID[containerTag];
-    // if (prevComponent) {
-    //   var prevWrappedElement = prevComponent._currentElement;
-    //   var prevElement = prevWrappedElement.props;
-    //   if (shouldUpdateReactComponent(prevElement, nextElement)) {
-    //     ReactUpdateQueue.enqueueElementInternal(prevComponent, nextWrappedElement);
-    //     if (callback) {
-    //       ReactUpdateQueue.enqueueCallbackInternal(prevComponent, callback);
-    //     }
-    //     return prevComponent;
-    //   }
-    // }
-
     var instance = instantiateReactComponent(nextWrappedElement, false);
 
     // The initial render is synchronous but any updates that happen during
@@ -141,4 +171,4 @@ var ReactHostMount = {
 
 };
 
-module.exports = ReactHostMount;
+module.exports = ReactTestMount;
diff --git a/src/renderers/testing/ReactTestRenderer.js b/src/renderers/testing/ReactTestRenderer.js
index ba6659fc4f6f9..b2d18464629bc 100644
--- a/src/renderers/testing/ReactTestRenderer.js
+++ b/src/renderers/testing/ReactTestRenderer.js
@@ -11,6 +11,7 @@
 
 'use strict';
 
+var ReactComponentEnvironment = require('ReactComponentEnvironment');
 var ReactDefaultBatchingStrategy = require('ReactDefaultBatchingStrategy');
 var ReactEmptyComponent = require('ReactEmptyComponent');
 var ReactMultiChild = require('ReactMultiChild');
@@ -62,6 +63,11 @@ ReactTestComponent.prototype.receiveComponent = function(
   this.updateChildren(nextElement.props.children, transaction, context);
 };
 ReactTestComponent.prototype.getHostNode = function() {};
+ReactTestComponent.prototype.getPublicInstance = function() {
+  // I can't say this makes a ton of sense but it seems better than throwing.
+  // Maybe we'll revise later if someone has a good use case.
+  return null;
+};
 ReactTestComponent.prototype.unmountComponent = function() {};
 ReactTestComponent.prototype.toJSON = function() {
   var {children, ...props} = this._currentElement.props;
@@ -125,6 +131,11 @@ ReactEmptyComponent.injection.injectEmptyComponentFactory(function() {
   return new ReactTestEmptyComponent();
 });
 
+ReactComponentEnvironment.injection.injectEnvironment({
+  processChildrenUpdates: function() {},
+  replaceNodeWithMarkup: function() {},
+});
+
 var ReactTestRenderer = {
   create: ReactTestMount.render,
 
diff --git a/src/renderers/testing/__tests__/ReactTestRenderer-test.js b/src/renderers/testing/__tests__/ReactTestRenderer-test.js
index 1d789c9ffcae0..e35e20d6d3d90 100644
--- a/src/renderers/testing/__tests__/ReactTestRenderer-test.js
+++ b/src/renderers/testing/__tests__/ReactTestRenderer-test.js
@@ -110,4 +110,91 @@ describe('ReactTestRenderer', function() {
     });
   });
 
+  it('updates types', function() {
+    var renderer = ReactTestRenderer.create(<div>mouse</div>);
+    expect(renderer.toJSON()).toEqual({
+      type: 'div',
+      props: {},
+      children: ['mouse'],
+    });
+
+    renderer.update(<span>mice</span>);
+    expect(renderer.toJSON()).toEqual({
+      type: 'span',
+      props: {},
+      children: ['mice'],
+    });
+  });
+
+  it('updates children', function() {
+    var renderer = ReactTestRenderer.create(
+      <div>
+        <span key="a">A</span>
+        <span key="b">B</span>
+        <span key="c">C</span>
+      </div>
+    );
+    expect(renderer.toJSON()).toEqual({
+      type: 'div',
+      props: {},
+      children: [
+        {type: 'span', props: {}, children: ['A']},
+        {type: 'span', props: {}, children: ['B']},
+        {type: 'span', props: {}, children: ['C']},
+      ],
+    });
+
+    renderer.update(
+      <div>
+        <span key="d">D</span>
+        <span key="c">C</span>
+        <span key="b">B</span>
+      </div>
+    );
+    expect(renderer.toJSON()).toEqual({
+      type: 'div',
+      props: {},
+      children: [
+        {type: 'span', props: {}, children: ['D']},
+        {type: 'span', props: {}, children: ['C']},
+        {type: 'span', props: {}, children: ['B']},
+      ],
+    });
+  });
+
+  it('does the full lifecycle', function() {
+    var log = [];
+    class Log extends React.Component {
+      render() {
+        log.push('render ' + this.props.name);
+        return <div />;
+      }
+      componentDidMount() {
+        log.push('mount ' + this.props.name);
+      }
+      componentWillUnmount() {
+        log.push('unmount ' + this.props.name);
+      }
+    }
+
+    var renderer = ReactTestRenderer.create(<Log key="foo" name="Foo" />);
+    renderer.update(<Log key="bar" name="Bar" />);
+    renderer.unmount();
+
+    expect(log).toEqual([
+      'render Foo',
+      'mount Foo',
+      'unmount Foo',
+      'render Bar',
+      'mount Bar',
+      'unmount Bar',
+    ]);
+  });
+
+  it('gives a ref to native components', function() {
+    var log = [];
+    ReactTestRenderer.create(<div ref={(r) => log.push(r)} />);
+    expect(log).toEqual([null]);
+  });
+
 });