SpyError.js

import React from 'react';
import PropTypes from 'prop-types';

export class Plot extends React.Component {

  drawPlot() {
    console.log('@@@@@@@@@@@@@ Called');
    return true;
  }

  componentDidMount() {
    this.drawPlot();
  }

  componentDidUpdate() {
    this.drawPlot();
  }

  render() {
    const { id } = this.props;
    return (
      <div id={id} className='class'></div>
    );
  }
}

Plot.propTypes = {
  data: PropTypes.array.isRequired,
  id: PropTypes.string.isRequired,
  layout: PropTypes.object.isRequired
};

export function findChart() {
  return Array.from(document.getElementsByClassName('chart'));
}


//In another file - test

import React from 'react';
import { mount } from 'enzyme';
import { Plot } from '<INSERT DIR HERE>';

describe('Plot', () => {
  describe('<Plot/> Component', () => {
    const data = [];
    const id = 'Chart_1';
    const layout = {};
    const afterDrawMock = jest.fn();

    const props = { id, data, layout, afterDraw: afterDrawMock };

    const wrapper = mount(<Plot {...props}></Plot>);
    const spyDrawPlot = jest.spyOn(wrapper.instance(), 'drawPlot');

    it('should call drawPlot method', () => {
      console.log('Call sequence');
      wrapper.update();
      expect(spyDrawPlot).toHaveBeenCalled();
    });
  });
});