5-kyu-the-hashtag-generator.js

// 5 kyu | The Hashtag Generator
// https://www.codewars.com/kata/the-hashtag-generator/

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/**
 * The marketing team is spending way too much time typing in hashtags.
 * Let's help them with our own Hashtag Generator!
 *
 * Here's the deal:
 * - It must start with a hashtag (#).
 * - All words must have their first letter capitalized.
 * - If the final result is longer than 140 chars it must return false.
 * - If the input or the result is an empty string it must return false.
 *
 * @param {string} str
 * @returns {string}
 */
const generateHashtag = str => {
  str = str
    .split(/\s+/)
    .filter(w => w.length)
    .map(w => `${w[0].toLocaleUpperCase()}${w.slice(1)}`)
    .join('');
  return 0 < str.length && str.length < 140 ? `#${str}` : false;
};

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// console.log(generateHashtag(''));
// console.log(generateHashtag('Do We have A Hashtag'));

import { strictEqual } from 'assert';

strictEqual(
  generateHashtag(''),
  false,
  'Expected an empty string to return false',
);

strictEqual(generateHashtag(' '.repeat(200)), false, 'Still an empty string');

strictEqual(
  generateHashtag('Do We have A Hashtag'),
  '#DoWeHaveAHashtag',
  'Expected a Hashtag (#) at the beginning.',
);

strictEqual(
  generateHashtag('Codewars'),
  '#Codewars',
  'Should handle a single word.',
);

strictEqual(
  generateHashtag('Codewars Is Nice'),
  '#CodewarsIsNice',
  'Should remove spaces.',
);

strictEqual(
  generateHashtag('Codewars is nice'),
  '#CodewarsIsNice',
  'Should capitalize first letters of words.',
);

strictEqual(generateHashtag('code' + ' '.repeat(140) + 'wars'), '#CodeWars');

strictEqual(
  generateHashtag(
    'Looooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong Cat',
  ),
  false,
  'Should return false if the final word is longer than 140 chars.',
);

strictEqual(
  generateHashtag('a'.repeat(139)),
  '#A' + 'a'.repeat(138),
  'Should work',
);

strictEqual(generateHashtag('a'.repeat(140)), false, 'Too long');