v3/packages/design-system/atoms/typist/Typist.spec.tsx

import { shallow } from 'enzyme';
import * as React from 'react';
import { Typist } from './Typist';

jest.useFakeTimers();

it('correctly cycles through provided lines', () => {
  const lines = ['abcdef', 'ghijkl'];
  let view = shallow(<Typist charTimeout={100} resetTimeout={10000} lines={lines} />);

  jest.advanceTimersByTime(100 * lines[0].length);
  view = view.update();
  expect(view.text()).toBe(lines[0]);
});

it('correctly cycles through provided characters in a line', () => {
  const lines = ['abcdef'];

  let view = shallow(<Typist charTimeout={1} resetTimeout={100} lines={lines} />);

  Array(...lines[0]).forEach((_, idx) => {
    view = view.update();
    expect(view.text()).toBe(lines[0].slice(0, idx));
    jest.advanceTimersByTime(1);
  });
});