Array Flatten Exercise

arrayUtils.js

/*
 *****************************************************************************************
 * Source File
 * Copyright (C) 2019  IvanSnek
 *
 * [CHANGE HISTORY]
 * 1. 2019-Aug-13 (ivansnek) File created
 *
 *****************************************************************************************
 */

/**
 * This helper function allows to flatten a given array  e.g. [[1,2,[3]],4] -> [1,2,3,4].
 * If the value provided to the function is not a valid array it will return null.
 * @param {Array} values Given array to flatten
 * @returns {Array} The flatten version of the given value.
 */
function flattenArray(values) {
  if (Array.isArray(values)) {
    return values
      .join(",")
      .split(",")
      .map(val => parseInt(val));
  }
  return null;
}

module.exports = { flattenArray };

arrayUtils.test.js

/*
 *****************************************************************************************
 * Source File
 * Copyright (C) 2019  IvanSnek
 *
 * [CHANGE HISTORY]
 * 1. 2019-Aug-13 (ivansnek) File created
 *
 *****************************************************************************************
 */

const { flattenArray } = require("./arrayUtils.js");

/** Tests Values*/
const testValues1 = [1];
const testValues2 = [1, 3, 4, [23, 32]];
const testValues3 = [
  [[2, 3], [[23, 23, [9, 9, [10, [10]]]]]],
  1,
  9,
  [[23, 23, [9, 9, [10, [10]]]]],
  [9, 9, [10, [10]]]
];

test("arrayUtils.flattenArray should flatten a given valid array", () => {
  expect(flattenArray(testValues1)).toEqual([1]);
  expect(flattenArray(testValues2)).toEqual([1, 3, 4, 23, 32]);
  expect(flattenArray(testValues3)).toEqual([
    2,
    3,
    23,
    23,
    9,
    9,
    10,
    10,
    1,
    9,
    23,
    23,
    9,
    9,
    10,
    10,
    9,
    9,
    10,
    10
  ]);
});

test("arrayUtils.flattenArray should return null with no valid array values", () => {
  expect(flattenArray("testValue")).toBeNull();
  expect(flattenArray(null)).toBeNull();
  expect(flattenArray(undefined)).toBeNull();
  expect(flattenArray({})).toBeNull();
  expect(flattenArray({ key: 1 })).toBeNull();
});