Zalando - Coding Test

test.2.js

'use strict';

/* global CustomError, getLikedBrands, getTopBrandsForGender */

function solution(U, N) {
    return new Promise((resolve, reject) => {

        // Uniq function
        const uniq = list => Array.from( new Set(list) )
        
        getLikedBrands(U.id).then(likedBrands => likedBrands.length >= N
            // If liked brands are enough
            ? resolve(
                likedBrands
                    .slice(0, N)
                    .map(i => i.name)
            )

            // If not enough, get more brands
            : getTopBrandsForGender(U.gender).then(topBrands => {

                // Concat and unify brands list
                const allBrands = uniq(
                    [...likedBrands, ...topBrands]
                    .map(i => i.name)
                )

                allBrands.length >= N
                    // If all brands are enough
                    ? resolve(allBrands.slice(0, N))
                    // If still not enough
                    : reject(new CustomError('Not enough data'))
            })
        )
    });
}

But what if the the getLikedBrands(id) promise is rejected? You still need to check the getTopBrandsForGender(gender) Promise and return an array if the second api call returns some data. At the moment, you are only checking that promise if the first promise is resolved.

Did this solution pass all the test cases?

https://gist.github.com/marco-souza/a6f7c1af8a738ed14eac3e4d85e3d262