lodash/test/sortBy.spec.js

import lodashStable from 'lodash';
import sortBy from '../src/sortBy';

describe('sortBy', () => {
    const objects = [
        { a: 'x', b: 3 },
        { a: 'y', b: 4 },
        { a: 'x', b: 1 },
        { a: 'y', b: 2 },
    ];

    it('should sort in ascending order by `iteratee`', () => {
        const actual = lodashStable.map(
            sortBy(objects, (object) => object.b),
            'b',
        );

        expect(actual).toEqual([1, 2, 3, 4]);
    });

    it('should use `_.identity` when `iteratee` is nullish', () => {
        const array = [3, 2, 1];
        const values = [, null, undefined];
        const expected = lodashStable.map(values, lodashStable.constant([1, 2, 3]));

        const actual = lodashStable.map(values, (value, index) =>
            index ? sortBy(array, value) : sortBy(array),
        );

        expect(actual).toEqual(expected);
    });

    it('should work with `_.property` shorthands', () => {
        const actual = lodashStable.map(sortBy(objects.concat(undefined), 'b'), 'b');
        expect(actual).toEqual([1, 2, 3, 4, undefined]);
    });

    it('should work with an object for `collection`', () => {
        const actual = sortBy({ a: 1, b: 2, c: 3 }, Math.sin);
        expect(actual).toEqual([3, 1, 2]);
    });

    it('should move `NaN`, nullish, and symbol values to the end', () => {
        const symbol1 = Symbol ? Symbol('a') : null;
        const symbol2 = Symbol ? Symbol('b') : null;
        let array = [NaN, undefined, null, 4, symbol1, null, 1, symbol2, undefined, 3, NaN, 2];
        let expected = [1, 2, 3, 4, symbol1, symbol2, null, null, undefined, undefined, NaN, NaN];

        expect(sortBy(array)).toEqual(expected);

        array = [NaN, undefined, symbol1, null, 'd', null, 'a', symbol2, undefined, 'c', NaN, 'b'];
        expected = [
            'a',
            'b',
            'c',
            'd',
            symbol1,
            symbol2,
            null,
            null,
            undefined,
            undefined,
            NaN,
            NaN,
        ];

        expect(sortBy(array)).toEqual(expected);
    });

    it('should treat number values for `collection` as empty', () => {
        expect(sortBy(1)).toEqual([]);
    });

    it('should coerce arrays returned from `iteratee`', () => {
        const actual = sortBy(objects, (object) => {
            const result = [object.a, object.b];
            result.toString = function () {
                return String(this[0]);
            };
            return result;
        });

        expect(actual).toEqual([objects[0], objects[2], objects[1], objects[3]]);
    });

    it('should work as an iteratee for methods like `_.map`', () => {
        const actual = lodashStable.map(
            [
                [2, 1, 3],
                [3, 2, 1],
            ],
            sortBy,
        );
        expect(actual).toEqual([
            [1, 2, 3],
            [1, 2, 3],
        ]);
    });
});