Find top watchlisted movies among friends

You are working on a movie fanpage social site. It requires a new functionality to be implemented: find top watchlisted movies among friends.

Setup

Follow these steps if you are using zip/git mode (i.e. not available inside Devskiller in-browser IDE):

npm install – install dependencies
npm test – run all tests once (this will be used to evaluate your solutions)
npm run test:watch - run all tests in watch mode (optionally, you can use it locally if you prefer)

Task

Implement MoviesAnalyzer#topWatchlistedMoviesAmongFriends method that will return an array of top four movie titles, that have been most watchlisted by friends of a given user.
If there are no such movies, then an empty list should be returned or as many movies as possible.
Movies that have equal watchlist count, should be ordered alphabetically.

Example data

The data (movies and users) is available in data.json. Testcases are defined in testcases.json.

Movies collection

  {
    "title": "The Shawshank Redemption",
    "duration": "PT142M",
    "actors": [ "Tim Robbins", "Morgan Freeman", "Bob Gunton" ],
    "ratings": [],
    "favorites": [66380, 7001, 9250, 34139],
    "watchlist": [15291, 51417, 62289, 6146, 71389, 93707]
  },
  {
    "title": "The Godfather",
    "duration": "PT175M",
    "actors": [ "Marlon Brando", "Al Pacino", "James Caan" ],
    "ratings": [],
    "favorites": [15291, 51417, 7001, 9250, 71389, 93707],
    "watchlist": [62289, 66380, 34139, 6146]
  },
  {
    "title": "The Dark Knight",
    "duration": "PT152M",
    "actors": [ "Christian Bale", "Heath Ledger", "Aaron Eckhart" ],
    "ratings": [],
    "favorites": [15291, 7001, 9250, 34139, 93707],
    "watchlist": [51417, 62289, 6146, 71389]
  },
  {
    "title": "Pulp Fiction",
    "duration": "PT154M",
    "actors": [ "John Travolta", "Uma Thurman", "Samuel L. Jackson" ],
    "ratings": [],
    "favorites": [15291, 51417, 62289, 66380, 71389, 93707],
    "watchlist": [7001, 9250, 34139, 6146]
  },
  {
    "title": "Schindler's List",
    "duration": "PT195M",
    "actors": [
      "Liam Neeson",
      "Ralph Fiennes",
      "Ben Kingsley"
    ],
    "ratings": [{"userId": 62289, "rating": 8},{"userId": 66380, "rating": 5},{"userId": 6146, "rating": 6},{"userId": 71389, "rating": 7}],
    "favorites": [62289, 66380, 6146, 71389],
    "watchlist": [15291, 51417, 7001, 9250, 93707]
  },

Users collection

    {
        "userId": 15291,
        "email": "Constantin_Kuhlman15@yahoo.com",
        "friends": [7001, 51417, 62289]
    },
    {
        "userId": 7001,
        "email": "Keven6@gmail.com",
        "friends": [15291, 51417, 62289, 66380]
    },
    {
        "userId": 51417,
        "email": "Margaretta82@gmail.com",
        "friends": [15291, 7001, 9250]
    },
    {
        "userId": 62289,
        "email": "Marquise.Borer@hotmail.com",
        "friends": [15291, 7001]
    }

Example output

Your implementation should return following output for userId=62289 for example data:

["Schindler's List", "The Lord of the Rings: The Return of the King", "Pulp Fiction",  "The Shawshank Redemption"]

In the example above, user with id 62289 has two friends: user with id=15291 and with id=7001. Schindler's List is watchlisted by both users, so it will be the most watchlisted.