class Math extends React.Component {
constructor(props) {
   super(props);
}

sum(a, b){
  return a+b;
}
export default Math;

import { Math } from './Math'

 describe('Math', () => {
 it('should add correctly', () => {
  const result = Math.sum(10, 10);
  expect(result).toEqual(20);
 }