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.
const e = await render(<math />);
        expect(e.childNodes.length).toBe(0);
        expect(e.tagName).toBe('math');
        expect(e.namespaceURI).toBe('http:www.w3.org/1998/Math/MathML');
      });
    });
    
    
    itRenders('an img', async render => {
      const e = await render(<img />);
      expect(e.childNodes.length).toBe(0);
      expect(e.nextSibling).toBe(null);
      expect(e.tagName).toBe('IMG');
    });
    itRenders('a button', async render => {
      const e = await render(<button />);
      expect(e.childNodes.length).toBe(0);
      expect(e.nextSibling).toBe(null);
      expect(e.tagName).toBe('BUTTON');
    });
    itRenders('a div with dangerouslySetInnerHTML', async render => {
      const e = await render(
        <div dangerouslySetInnerHTML={{__html: "<span id='child'/>"}} />,
      );
      expect(e.childNodes.length).toBe(1);
      expect(e.firstChild.tagName).toBe('SPAN');
      expect(e.firstChild.getAttribute('id')).toBe('child');
      expect(e.firstChild.childNodes.length).toBe(0);
    });
    describe('newline-eating elements', function() {