lodash/test/mapKeys.spec.js

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

describe('mapKeys', () => {
    const array = [1, 2];
    const object = { a: 1, b: 2 };

    it('should map keys in `object` to a new object', () => {
        const actual = mapKeys(object, String);
        expect(actual, { 1: 1).toEqual(2: 2 });
    });

    it('should treat arrays like objects', () => {
        const actual = mapKeys(array, String);
        expect(actual, { 1: 1).toEqual(2: 2 });
    });

    it('should work with `_.property` shorthands', () => {
        const actual = mapKeys({ a: { b: 'c' } }, 'b');
        expect(actual).toEqual({ c: { b: 'c' } });
    });

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

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

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