Shallow render components that define contextTypes

You now no longer have to pass an undocumented extra argument to the
shallow renderer for rendering components with contextTypes to work.

Fixes #3696

src/test/ReactTestUtils.js

@@ -26,6 +26,7 @@ var ReactUpdates = require('ReactUpdates');
 var SyntheticEvent = require('SyntheticEvent');
 
 var assign = require('Object.assign');
+var emptyObject = require('emptyObject');
 var findDOMNode = require('findDOMNode');
 
 var topLevelTypes = EventConstants.topLevelTypes;
@@ -369,6 +370,9 @@ assign(
 );
 
 ReactShallowRenderer.prototype.render = function(element, context) {
+  if (!context) {
+    context = emptyObject;
+  }
   var transaction = ReactUpdates.ReactReconcileTransaction.getPooled();
   this._render(element, transaction, context);
   ReactUpdates.ReactReconcileTransaction.release(transaction);

src/test/__tests__/ReactTestUtils-test.js

@@ -46,7 +46,7 @@ describe('ReactTestUtils', function() {
     });
 
     var shallowRenderer = ReactTestUtils.createRenderer();
-    shallowRenderer.render(<SomeComponent />, {});
+    shallowRenderer.render(<SomeComponent />);
 
     var result = shallowRenderer.getRenderOutput();
 
@@ -68,7 +68,7 @@ describe('ReactTestUtils', function() {
     });
 
     var shallowRenderer = ReactTestUtils.createRenderer();
-    shallowRenderer.render(<SomeComponent />, {});
+    shallowRenderer.render(<SomeComponent />);
     shallowRenderer.unmount();
 
     expect(componentWillUnmount).toBeCalled();
@@ -82,7 +82,7 @@ describe('ReactTestUtils', function() {
     });
 
     var shallowRenderer = ReactTestUtils.createRenderer();
-    shallowRenderer.render(<SomeComponent />, {});
+    shallowRenderer.render(<SomeComponent />);
 
     var result = shallowRenderer.getRenderOutput();
 
@@ -123,7 +123,7 @@ describe('ReactTestUtils', function() {
     });
 
     var shallowRenderer = ReactTestUtils.createRenderer();
-    shallowRenderer.render(<SomeComponent />, {});
+    shallowRenderer.render(<SomeComponent />);
     var result = shallowRenderer.getRenderOutput();
     expect(result.type).toBe('div');
     expect(result.props.children).toEqual([
@@ -131,7 +131,7 @@ describe('ReactTestUtils', function() {
       <span className="child2" />
     ]);
 
-    shallowRenderer.render(<SomeComponent aNew="prop" />, {});
+    shallowRenderer.render(<SomeComponent aNew="prop" />);
     var updatedResult = shallowRenderer.getRenderOutput();
     expect(updatedResult.type).toBe('a');
 
@@ -143,6 +143,22 @@ describe('ReactTestUtils', function() {
     expect(updatedResultCausedByClick.props.className).toBe('was-clicked');
   });
 
+  it('can shallowly render components with contextTypes', function() {
+    var SimpleComponent = React.createClass({
+      contextTypes: {
+        name: React.PropTypes.string,
+      },
+      render: function() {
+        return <div />;
+      },
+    });
+
+    var shallowRenderer = ReactTestUtils.createRenderer();
+    shallowRenderer.render(<SimpleComponent />);
+    var result = shallowRenderer.getRenderOutput();
+    expect(result).toEqual(<div />);
+  });
+
   it('Test scryRenderedDOMComponentsWithClass with TextComponent', function() {
     var renderedComponent = ReactTestUtils.renderIntoDocument(<div>Hello <span>Jim</span></div>);
     var scryResults = ReactTestUtils.scryRenderedDOMComponentsWithClass(