Use the correct SyntheticEvent for TestUtils.Simulate

src/renderers/dom/client/eventPlugins/SimpleEventPlugin.js

@@ -487,7 +487,7 @@ var SimpleEventPlugin = {
 
   eventTypes: eventTypes,
 
-  extractEvents: function(
+  extractEventConstructor: function(
     topLevelType,
     targetInst,
     nativeEvent,
@@ -604,8 +604,27 @@ var SimpleEventPlugin = {
       'SimpleEventPlugin: Unhandled event type, `%s`.',
       topLevelType
     );
+    return EventConstructor;
+  },
+
+  extractEvents: function(
+    topLevelType,
+    targetInst,
+    nativeEvent,
+    nativeEventTarget
+  ) {
+    var EventConstructor = SimpleEventPlugin.extractEventConstructor(
+      topLevelType,
+      targetInst,
+      nativeEvent,
+      nativeEventTarget
+    );
+    if (!EventConstructor) {
+      return null;
+    }
+
     var event = EventConstructor.getPooled(
-      dispatchConfig,
+      topLevelEventsToDispatchConfig[topLevelType],
       targetInst,
       nativeEvent,
       nativeEventTarget

src/test/ReactTestUtils.js

@@ -472,6 +472,12 @@ ReactShallowRenderer.prototype._render = function(element, transaction, context)
  * - ... (All keys from event plugin `eventTypes` objects)
  */
 function makeSimulator(eventType) {
+  var dispatchConfig = EventPluginRegistry.eventNameDispatchConfigs[eventType];
+  // Get the topLevelType so we can extract the right SyntheticEvent type so we
+  // copy properties correctly from the native event and also get our warnings
+  // related to pooling.
+  var topLevelType = EventConstants.topLevelTypes[dispatchConfig.dependencies[0]];
+
   return function(domComponentOrNode, eventData) {
     var node;
     invariant(
@@ -485,20 +491,30 @@ function makeSimulator(eventType) {
       node = domComponentOrNode;
     }
 
-    var dispatchConfig =
-      EventPluginRegistry.eventNameDispatchConfigs[eventType];
+    var EventPlugin = EventPluginRegistry.getPluginModuleForEvent({dispatchConfig});
 
+    // Assign the extra event data to the native event, ensuring we copy they
+    // correct data over for a given event. Other fields will be dropped.
     var fakeNativeEvent = new Event();
-    fakeNativeEvent.target = node;
+    Object.assign(fakeNativeEvent, {target: node}, eventData);
+
+    var inst = ReactDOMComponentTree.getInstanceFromNode(node);
+
+    var SyntheticEventConstructor = EventPlugin.extractEventConstructor(
+      topLevelType,
+      domComponentOrNode,
+      fakeNativeEvent,
+      node
+    );
+
     // We don't use SyntheticEvent.getPooled in order to not have to worry about
     // properly destroying any properties assigned from `eventData` upon release
-    var event = new SyntheticEvent(
+    var event = new SyntheticEventConstructor(
       dispatchConfig,
-      ReactDOMComponentTree.getInstanceFromNode(node),
+      domComponentOrNode,
       fakeNativeEvent,
       node
     );
-    Object.assign(event, eventData);
 
     if (dispatchConfig.phasedRegistrationNames) {
       EventPropagators.accumulateTwoPhaseDispatches(event);

src/test/__tests__/ReactTestUtils-test.js

@@ -474,6 +474,29 @@ describe('ReactTestUtils', function() {
     expect(handler).not.toHaveBeenCalled();
   });
 
+  it('should not warn when simulating events with extra properties', function() {
+    spyOn(console, 'error');
+
+    var CLIENT_X = 100;
+
+    var Component = React.createClass({
+      handleClick: function(e) {
+        expect(e.clientX).toBe(CLIENT_X);
+      },
+      render: function() {
+        return <div onClick={this.handleClick} />;
+      },
+    });
+
+    var element = document.createElement('div');
+    var instance = ReactDOM.render(<Component />, element);
+    ReactTestUtils.Simulate.click(
+      ReactDOM.findDOMNode(instance),
+      {clientX: CLIENT_X}
+    );
+    expect(console.error.calls.length).toBe(0);
+  });
+
   it('can scry with stateless components involved', function() {
     var Stateless = () => <div><hr /></div>;
     var SomeComponent = React.createClass({