Facebook is using and recommending the Jest test framework together with React's TestUtils. So far, this has worked fairly well for me.
It allows you to write unit tests for React components in a similar way as for other JavaScript modules.
From their Jest intro:
import React from 'react';
import ReactDOM from 'react-dom';
import TestUtils from 'react-addons-test-utils';
import CheckboxWithLabel from '../CheckboxWithLabel';
describe('CheckboxWithLabel', () => {
it('changes the text after click', () => {
// Render a checkbox with label in the document
const checkbox = TestUtils.renderIntoDocument(
<CheckboxWithLabel labelOn="On" labelOff="Off" />
);
const checkboxNode = ReactDOM.findDOMNode(checkbox);
// Verify that it's Off by default
expect(checkboxNode.textContent).toEqual('Off');
// Simulate a click and verify that it is now On
TestUtils.Simulate.change(
TestUtils.findRenderedDOMComponentWithTag(checkbox, 'input')
);
expect(checkboxNode.textContent).toEqual('On');
});
});