expect(() => ReactDOM.render(<WillMount />, container)).toWarnDev(
      'Unsafe legacy lifecycles will not be called for components using new component APIs.\n\n' +
        'WillMount uses getSnapshotBeforeUpdate() but also contains the following legacy lifecycles:\n' +
        '  UNSAFE_componentWillMount\n\n' +
        'The above lifecycles should be removed. Learn more about this warning here:\n' +