lodash/test/flatMapDepth.spec.js

import lodashStable from 'lodash';
import { identity } from './utils';
import flatMapDepth from '../src/flatMapDepth';

describe('flatMapDepth', () => {
    const array = [1, [2, [3, [4]], 5]];

    it('should use a default `depth` of `1`', () => {
        expect(flatMapDepth(array, identity)).toEqual([1, 2, [3, [4]], 5]);
    });

    it('should use `_.identity` when `iteratee` is nullish', () => {
        const values = [, null, undefined];
        const expected = lodashStable.map(values, lodashStable.constant([1, 2, [3, [4]], 5]));

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

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

    it('should treat a `depth` of < `1` as a shallow clone', () => {
        lodashStable.each([-1, 0], (depth) => {
            expect(flatMapDepth(array, identity, depth)).toEqual([1, [2, [3, [4]], 5]]);
        });
    });

    it('should coerce `depth` to an integer', () => {
        expect(flatMapDepth(array, identity, 2.2)).toEqual([1, 2, 3, [4], 5]);
    });
});