__tests__LocaleInput.js

jest.dontMock('../LocaleInput');

describe('LocaleInput', () => {
  it('should render all locales without locales prop', () => {
    const React = require('react/addons');
    const LocaleInput = require('../LocaleInput');
    
    const input = TestUtils.renderIntoDocument(<LocaleInput />);
    const select = TestUtils.findRenderedDOMComponentWithTag(input, 'select');
  });
});

Input.js

const Input = React.createClass({
  render() {
    if (this.props.type === 'select') {
      return (
        <select {...this.props}>{this.props.children}</select>;
      );
    }
  }
})

LocaleInput.js

const locales = {
  ru: 'Русский',
  en: 'English'
};

const LocaleInput = React.createClass({
  renderOptions() {
    return this.props.locales.map((locale) => {
      return (
        <option value={locale} key={locale}>
          {locales[locale]}
        </option>
      );
    });
  },
  render() {
    return (
      <Input type="select">
        {this.renderOptions()}
      </Input>
    );
  }
})