It seems problematic to allow arbitary non-lowercase attribute on HTML nodes. Because the server has no ability to keep them case sensitive (HTML isn't). So they will end up different on the client.

We should probably warn if the attribute is not a known one *and* is not lowercase.
expect(container.firstChild.innerHTML).toBe(html);
    });
    it('render and then updates innerHTML and preserves whitespace', () => {
      const container = document.createElement('div');
      const html = '\n  \t  <span>  \n  testContent1  \t  </span>  \n  \t';
      const elem = <div dangerouslySetInnerHTML={{__html: html}} />;
      ReactDOM.render(elem, container);
      const html2 = '\n  \t  <div>  \n  testContent2  \t  </div>  \n  \t';
      const elem2 = <div dangerouslySetInnerHTML={{__html: html2}} />;
      ReactDOM.render(elem2, container);
      expect(container.firstChild.innerHTML).toBe(html2);
    });
  });
  describe('Attributes with aliases', function() {
    it('sets aliased attributes on HTML attributes', function() {
      spyOn(console, 'error');
      var el = ReactTestUtils.renderIntoDocument(<div class="test" />);
      expect(el.className).toBe('test');
      expectDev(console.error.calls.argsFor(0)[0]).toContain(
        'Warning: Invalid DOM property `class`. Did you mean `className`?',
      );
    });
    it('sets incorrectly cased aliased attributes on HTML attributes with a warning', function() {
      spyOn(console, 'error');
      var el = ReactTestUtils.renderIntoDocument(<div cLASS="test" />);
      expect(el.className).toBe('test');
      expectDev(console.error.calls.argsFor(0)[0]).toContain(
        'Warning: Invalid DOM property `cLASS`. Did you mean `className`?',
      );
    });