refactoring.rb

require "yaml"

require "minitest/autorun"
require "minitest/pride"

class TestStatement < Minitest::Test
  def statement(invoice, plays)
    total_amount = 0
    volume_credits = 0
    result = "Statement for #{invoice.fetch("customer")}\n"
    format = ->(currency) { "$#{currency.to_s.reverse.chars.each_slice(3).map(&:join).join(?,).reverse}.00" }

    invoice.fetch("performances").each do |perf|
      play = plays.fetch(perf.fetch("playID"))
      this_amount = 0

      case play.fetch("type")
      when "tragedy"
        this_amount = 40000
        this_amount += 1000 * (perf.fetch("audience") - 30) if perf.fetch("audience") > 30
      when "comedy"
        this_amount = 30000
        this_amount += 10000 + 500 * (perf.fetch("audience") - 20) if perf.fetch("audience") > 20
        this_amount += 300 * perf.fetch("audience")
      else
        fail "Unknown type: #{play.fetch("type")}"
      end

      # add volume credits
      volume_credits += [perf.fetch("audience") - 30, 0].max

      # add extra credit for every ten comedy attendees
      volume_credits += perf.fetch("audience") / 5 if play.fetch("type") == "comedy"

      # print line for this order
      result << "  #{play.fetch("name")}: #{format[this_amount / 100]} (#{perf.fetch("audience")} seats)\n"
      total_amount += this_amount
    end

    result << "Amount owed is #{format[total_amount / 100]}\n"
    result << "You earned #{volume_credits} credits\n"
    result
  end

  def test_statement
    plays = YAML.load(<<~PLAYS)
      hamlet:
        name: Hamlet
        type: tragedy
      as-like:
        name: As You Like It
        type: comedy
      othello:
        name: Othello
        type: tragedy
    PLAYS

    invoices = YAML.load(<<~INVOICES)
      - customer: BigCo
        performances:
        - playID: hamlet
          audience: 55
        - playID: as-like
          audience: 35
        - playID: othello
          audience: 40
    INVOICES

    assert_equal <<~EXPECTED, statement(invoices.first, plays)
      Statement for BigCo
        Hamlet: $650.00 (55 seats)
        As You Like It: $580.00 (35 seats)
        Othello: $500.00 (40 seats)
      Amount owed is $1,730.00
      You earned 47 credits
    EXPECTED
  end
end