For consideration.

These warnings are already covered by renderers based on react-reconciler. Maybe we don't gain that much by mirroring them in the shallow renderer? Maybe it's not worth the added complexity? Particularly with more complicated warnings like the ones being added for #12419 and #12404.
state = {};
      static getDerivedStateFromProps() {
        return null;
      }
      componentWillMount() {}
      UNSAFE_componentWillReceiveProps() {}
      componentWillUpdate() {}
      render() {
        return null;
      }
    }
    shallowRenderer = createRenderer();
    expect(() => shallowRenderer.render(<AllLegacyLifecycles />)).toWarnDev(
      'Unsafe legacy lifecycles will not be called for components using the new getDerivedStateFromProps() API.\n\n' +
        'AllLegacyLifecycles uses getDerivedStateFromProps() but also contains the following legacy lifecycles:\n' +
        '  componentWillMount\n' +
        '  UNSAFE_componentWillReceiveProps\n' +
        '  componentWillUpdate\n\n' +
        'The above lifecycles should be removed. Learn more about this warning here:\n' +
        'https://fb.me/react-async-component-lifecycle-hooks',
    );
    class WillMount extends React.Component {