TDD Example

tdd-example.rb

require 'minitest/autorun'
require 'json'
require 'httparty'

class Movie
  CHILDRENS   = "0"
  REGULAR     = "1"
  NEW_RELEASE = "2"

  attr_accessor :price_code, :title

  def initialize(title:, price_code:)
    @title = title
    @price_code = price_code
  end

  def price_for_week
    {
      "0" => 3,
      "1" => 10,
      "2" => 20
    }.fetch(@price_code)
  end
end

class Rental
  attr_accessor :movie, :days_rented

  def initialize(movie:, days_rented:) 
    @movie = movie
    @days_rented = days_rented
  end

  def price_per_day
    @movie.price_for_week / 7
  end
end

class Customer
  @@rentals = []

  def initialize(name:, rental:)
    @name = name
    @@rentals << rental
  end

  def rentals
    @@rentals
  end
end

class Statement
  attr_accessor :total_owed

  def initialize(customer:, rental:, movie:)
    @customer = customer
    @rental = rental
    @movie = movie
  end

  def tally_total_owed
    @total_owed = @customer.rentals.map { |rental|
      rental.price_per_day * rental.days_rented
    }.inject(:+)
    self
  end
end

class Dollar
  attr_reader :amount
  def initialize original
    @original = original
  end
  def times multiplier
    @amount = [@original, multiplier].inject(:*)
    self
  end
end

describe "Dollar" do
  it "multiplication" do
    five = Dollar.new(5)
    multiplied = five.times(2)
    assert_equal(10, multiplied.amount)
  end

  it "multiplication without modifying original" do
    five = Dollar.new(5)
    multiplied = five.times(2)
    assert_equal(10, multiplied.amount)
    multi = five.times(3)
    assert_equal(15, multi.amount)
  end
end

describe "Statement" do
  it "calculates total owed for users who rented movies" do

    movie = Movie.new(
      title: 'john wick 3',
      price_code: "2"
    )
    rental = Rental.new(
      movie: movie,
      days_rented: 12
    )
    customer = Customer.new(
      name: 'Dain Miller',
      rental: rental
    )
    statement = Statement.new(
      customer: customer,
      rental: rental,
      movie: movie
    ).tally_total_owed

    assert_equal(24, statement.total_owed)
  end
end

module Clients
  module Cacheable
    def cache data
      File.open('data.json', 'w') { |file| file.write(data) }
    end
    def file_exists?
      not File.read('data.json').empty?
    end
  end
  module Parseable
    def parse data
      JSON.parse data
    end
  end
  module Fetchable
    def fetch url
      HTTParty.get(url).body
    end
  end
  class Github
    include Fetchable, Cacheable, Parseable
    def initialize(org:)
      cache fetch "https://api.github.com/orgs/#{org}/repos" unless file_exists?
      @org ||= parse File.read('data.json')
    end
    def repos
      @org
    end
  end
end

describe "GithubClient" do
  it "returns the repos for a specific org passed in" do
    client = Clients::Github.new(org: 'opensourcecourses')
    assert_equal(1, client.repos.count)
  end
end