MOUNT .0 (WrapperComponent)
MOUNT .0 (MockComponent)
MOUNT .0 (span)
UNMOUNT .0 (span)
UNMOUNT .0 (MockComponent)
MOUNT .0 (MockComponent)
MOUNT .0 (span) 

var container = document.createElement('div');

var MockComponent = React.createClass({
  render: function() {
    return <span />;
  }
});

var WrapperComponent = React.createClass({
  render: function() {
    return this.props.children || <MockComponent />;
  }
});

React.renderComponent(<WrapperComponent />, container);

React.renderComponent(
  <WrapperComponent><MockComponent /></WrapperComponent>,
  container
);