ErrorPro

import React, { Component } from 'react';

const DumpComponent = props => (
  <button onClick={props.onClick}>{props.label}</button>
);

// or

class DumpComponent extends Component {
  render() {

ErrorPro

import React from 'react';
import Button from './Button';
import renderer from 'react-test-renderer';
import Enzyme, { mount } from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';

Enzyme.configure({ adapter: new Adapter() });

/* other tests */

ErrorPro

import React, { Component } from 'react';
import PropTypes from 'prop-types';

class Button extends Component {
  state = {
    counter: 0,
  }

  render() {
    const { label, onClick } = this.props;

ErrorPro

function sum(a, b) {
  return a + b;
}