Run the [`fixtures/ssr` test harness](https://github.com/facebook/react/tree/master/fixtures/ssr). In the terminal, the following warning is logged:

```
Warning: Unknown prop `onClick` on <a> tag. Remove this prop from the element. For details, see https://fb.me/react-unknown-prop
  in a (at Page.js:12)
  in p (at Page.js:18)
  in div (at Page.js:17)
  in Page (at App.js:12)
  in div (at App.js:10)
  in body (at Chrome.js:17)
  in html (at Chrome.js:9)
  in Chrome (at App.js:9)
  in App (at render.js:18)
```

SSR behavior should match client-side behavior and not warn for a valid attribute.
render() {
            return <div />;
          }
          getChildContext() {
            return {foo: 'bar'};
          }
        }
        return render(<Component />);
      },
    );
    itThrowsWhenRendering(
      'if getChildContext returns a value not in childContextTypes',
      render => {
        class Component extends React.Component {
          render() {
            return <div />;
          }
          getChildContext() {
            return {value1: 'foo', value2: 'bar'};
          }
        }
        Component.childContextTypes = {value1: PropTypes.string};
        return render(<Component />);
      },
    );
  });
  describe('refs', function() {
    it('should not run ref code on server', async () => {
      let refCount = 0;
      class RefsComponent extends React.Component {