mergeArrayToObject.js

const _ = require('lodash');

const primary = { colors: ['#123454', '#123223'] };
const info = { colors: ['#EEFF44', '#FF2211'] };
const success = { colors: ['#773388', '#AA3322'] };

const original = [{ primary: primary.colors }, { info: info.colors }, { success: success.colors }];

const expected = {
  primary: primary.colors,
  info: info.colors,
  success: success.colors,
};

const log = {
  describe(str) {
    console.log(`describe: ${str}`);
  },

  it(str) {
    console.log(`\t it ${str}`);
  },

  assertEquals(str) {
    console.log(`\t\tResult: ${str}`);
  },

  error(str) {
    console.log(`\t\tResult: ${str}`);
  },
};

test();

function test() {
  // assertEquals(expected, actual);

  describe('mergeArrayToObject', function() {
    it('should return a empty object when input is undefined', function() {
      const actual = mergeArrayToObject();
      assertEquals({}, actual);
    });

    it('should return a empty object when input is null', function() {
      const actual = mergeArrayToObject(null);
      assertEquals({}, actual);
    });

    it('should return a empty object when input is an empty array', function() {
      const actual = mergeArrayToObject([]);
      assertEquals({}, actual);
    });

    it('should merge object in array to final object', function() {
      const actual = mergeArrayToObject(original);
      assertEquals(expected, actual);
    });

    it('should throw an error when input is not an array', function() {
      assertError(function() {
        mergeArrayToObject({});
      });
    });
  });
}

function mergeArrayToObject(arr) {
  const myArray = arr || [];
  if (!Array.isArray(myArray)) {
    throw new Error('Input is not an array');
  }

  const result = myArray.reduce(function(previous, obj) {
    return {
      ...previous,
      ...obj,
    };
  }, {});

  return result;
}

function describe(description, fn) {
  log.describe(description);

  fn();
}

function it(sentence, fn) {
  log.it(sentence);

  fn();
}

function assertEquals(expected, actual) {
  if (_.isEqual(expected, actual)) {
    log.assertEquals('Passed');
  } else {
    log.error(`${JSON.stringify(actual)} is not expected as ${JSON.stringify(expected)}`);
  }
}

function assertError(fn, message = '') {
  try {
    fn();

    log.error('Expected an error');
  } catch (error) {
    log.assertEquals('Passed');
  }
}