Example Jest Test

index.test.js

import titleCase from '.';

const data = [
  {
    value: 'lord of the flies',
    expected: 'Lord of the Flies',
  },
  {
    value: 'once upon a time',
    expected: 'Once Upon a Time',
  },
];

describe.each(data)('titleCase', ({
  value,
  expected
}) => {
  it(`should convert "${value}" to "${expected}"`, () => {
    expect(
      titleCase(value),
    ).toBe(expected);
  });
});