Testing for a button's disabled state in React

I have a simple component that I want to test using React and ReactUtils.

var TextConfirmButton = React.createClass({
  getInitialState: function() {
    return {
      inputText: '',
      confirmText: this.props.confirmText,
      buttonEnabled: false,
      inputEnabled: true
    }
  },

  handleChange: function(event) {
    this.setState({ inputText: event.target.value });
  },

  handleConfirm: function() {
    this.props.onConfirmClick();
    // When user clicks the confirm button, disable both the input and button.
    this.setState({ buttonEnabled: false, inputEnabled: false });
  },

  render: function() {
    return (
      <div>
        <input onChange={this.handleChange} disabled={!this.state.inputEnabled} type='text' ref='text' placeholder={this.state.confirmText} />
        <button onClick={this.handleConfirm} disabled={this.state.inputText !== this.state.confirmText} className='btn btn-danger'>Delete</button>
      </div>
    )
  }
})

Is there a way to test for a button's disabled state?

I've attempted:

var TestUtils = React.addons.TestUtils;

describe('TextConfirmButton', function () {
  it('starts with confirm button disabled', function () {
    var onConfirmClick = function() {
      console.log("Confirm click");
    }

    var textConfirmButton = TestUtils.renderIntoDocument(
      <TextConfirmButton confirmText="example" onConfirmClick={this.onConfirmClick} />
    );

    var textConfirmButtonNode = ReactDOM.findDOMNode(textConfirmButton);

    expect(textConfirmButtonNode.disabled).toEqual('disabled');
  });
});

But the test fails, with the error: textConfirmButtonNode.disabled undefined. So .disabled is obviously the wrong way to go about this.

Any suggestions?