gistfile1.js

let TestUtils = require("react/addons").addons.TestUtils;

class LoginPage extends React.Component {
    render() {
        return (
            <form className="LoginPage">
                <input type="email" value={this.state.email} />
                <input type="password" value={this.state.password} />
                <input type="submit" value="Login" />
            </form>
        );
    }
}

let element = TestUtils.renderIntoDocument(<LoginPage />);
let emailNode = element.email.getDOMNode();

expect(emailNode.value).to.equal("[email protected]");

// Potentially multiple ways to change the value
element.password.getDOMNode().value = "[email protected]";
TestUtils.Simulate.change(element.password.getDOMNode(), {
  target: {
    value: "password"
  }
});

TestUtils.Simulate.click(element.login.getDOMNode());