this.gridNode = null;

...

componentDidUpdate(prevProps) {
  const node = this.getGridWrapperNode();
  if (!isEqual(this.props.data, prevProps.data) && (node && node.scrollTop > 0)) {
    node.scrollTop = 0;
  }
}

...

getGridWrapperNode = () => (
  this.gridNode && this.gridNode.getElementsByClassName('datagrid-grid-wrapper')[0]);

it('should reset gridWrapperNode scrollTop position if data has changed', () => {
    const mounted = mount(<Grid {...props} />);

    const element = document.createElement('div');
    element.classList.add('datagrid-grid-wrapper');
    element.scrollTop = 46;

    mounted.instance().gridNode = element;

    mounted.setProps({
      ...props,
      data: [{ val: 'ya' }],
    });

    wrapper.update();

    const el = mounted.instance().gridNode;
    expect(el.scrollTop).toEqual(0);
  });