const {shank} = require('./_30s.js');

test('shank is a Function', () => {
  expect(shank).toBeInstanceOf(Function);
});

const names = ['alpha', 'bravo', 'charlie'];

test('Returns an array with the added elements.', () => {
  expect(shank(names, 1, 0, 'delta')).toEqual(['alpha', 'delta', 'bravo', 'charlie']);
});

test('Returns an array with the removed elements.', () => {
  expect(shank(names, 1, 1)).toEqual(['alpha', 'charlie']);
});

test('Does not mutate the original array', () => {
  shank(names, 1, 0, 'delta');
  expect(names).toEqual(['alpha', 'bravo', 'charlie']);
});