test.js

var Toggler = require('./toggler');
var React = require('react/addons');
var assert = chai.assert;
var Simulate = React.addons.TestUtils.Simulate

describe('Toggler', function(){

  var toggler, el;

  beforeEach(function() {
    toggler = render(Toggler({buttonText: 'toggle'}, 'ohai!'));
    el = toggler.getDOMNode();
  });

  afterEach(function() {
    teardownComponent(toggler);
  });

  it('renders correctly', function(){
    assert.equal(toggler.refs.button.getDOMNode().textContent, 'toggle');
    assert.equal(toggler.refs.content.getDOMNode().textContent, 'ohai!');
  });

  it('toggles the content when the button is clicked', function() {
    assert.ok(toggler.getDOMNode().textContent.match('ohai!'));
    Simulate.click(toggler.refs.button.getDOMNode());
    assert.ok(!toggler.getDOMNode().textContent.match('ohai!'));
  });

});

function render(component) {
  var container = document.createElement('div');
  document.body.appendChild(container);
  React.renderComponent(component, container);
  return component;
}

function teardownComponent(component) {
  React.unmountComponentAtNode(component.getDOMNode().parentNode);
}

toggler.js

var React = require('react');
var div = React.DOM.div;
var button = React.DOM.button;

var Toggler = React.createClass({
  getInitialState: function() {
    return { isOpen: true };
  },

  toggle: function() {
    this.setState({isOpen: !this.state.isOpen});
  },

  render: function() {
    var content = this.state.isOpen ? this.props.children : null;
    return div({},
      button({ref: 'button', onClick: this.toggle}, this.props.buttonText),
      div({ref: 'content'}, content)
    );
  }
});

module.exports = Toggler;

Oh, regarding "unit" v. "intergration" tests.

Where is the integration in testing the DOM output of a component? It is a unit test. The unit outputs to the DOM. I'm still a little confused why people think that because you have a DOM you are suddenly doing an integration test. Again, the database model analogy, are those integration tests because there is a database around?

@rpflorence The database analogy is great! That's an interesting point of view, Ryan. Thank you :)