#5284 - Show a friendly error when using TestUtils.Simulate with shallow rendering

src/test/ReactTestUtils.js

@@ -470,6 +470,11 @@ ReactShallowRenderer.prototype._render = function(element, transaction, context)
 function makeSimulator(eventType) {
   return function(domComponentOrNode, eventData) {
     var node;
+    invariant(
+      !React.isValidElement(domComponentOrNode),
+      'TestUtils.Simulate expects a component instance and not a ReactElement.' +
+      'TestUtils.Simulate will not work if you are using shallow rendering.'
+    );
     if (ReactTestUtils.isDOMComponent(domComponentOrNode)) {
       node = findDOMNode(domComponentOrNode);
     } else if (domComponentOrNode.tagName) {

src/test/__tests__/ReactTestUtils-test.js

@@ -421,6 +421,27 @@ describe('ReactTestUtils', function() {
     expect(handler).toHaveBeenCalledWith(jasmine.objectContaining({target: node}));
   });
 
+  it('should throw when attempting to use ReactTestUtils.Simulate with shallow rendering', function() {
+    var SomeComponent = React.createClass({
+      render: function() {
+        return (
+          <div onClick={this.props.handleClick}>
+            hello, world.
+          </div>
+        );
+      },
+    });
+    var handler = jasmine.createSpy('spy');
+    var shallowRenderer = ReactTestUtils.createRenderer();
+    shallowRenderer.render(<SomeComponent handleClick={handler} />);
+    var result = shallowRenderer.getRenderOutput();
+    expect(() => ReactTestUtils.Simulate.click(result)).toThrow(
+      'TestUtils.Simulate expects a component instance and not a ReactElement.' +
+      'TestUtils.Simulate will not work if you are using shallow rendering.'
+    );
+    expect(handler).not.toHaveBeenCalled();
+  });
+
   it('can scry with stateless components involved', function() {
     var Stateless = () => <div><hr /></div>;
     var SomeComponent = React.createClass({