tamda/src/list/sort.spec.ts

Practical functional programming library for TypeScript

import { sort } from './sort';

describe('sort', () => {
  it('should immutably sort an array based on the specified compare function', () => {
    const array = [null, undefined, NaN];
    const fn = (t: any) => (t === null ? 1 : t == null ? 0 : -1);

    const results = [
      sort(array, fn),
      sort (fn) (array),
    ];

    results.forEach(result => {
      expect(result).toEqual([NaN, null, undefined]);
      expect(result).not.toBe(array);
    });
  });

  it('should immutably sort an array with a default compare function', () => {
    const array = [3, 1, 2];

    const results = [
      sort(array),
      sort () (array),
    ];

    results.forEach(result => {
      expect(result).toEqual([1, 2, 3]);
      expect(result).not.toBe(array);
    });
  });
});