Pay the bills

pay_bills.rb

## Pay the bills!
#
#  write the function bellow that tells which bills the user is able to
#  pay with the available budget
#
#  the budget parameter is a number representing the amount available
#  the bills parameter is a array of hash objects in the following format:
#  [
#    { value: 100, type: :water, priority: 1 },
#    { value: 200, type: :credit_card },
#    { value: 100, type: :phone },
#    { value: 150, type: :electricity, priority: 2 }
#  ]
#  
#  the expected response is composed of three array:
#    - the bills paid in full,
#    - the bills partially paid,
#    - the bills unpaid
#
#  some examples:
#  if the budget is 900 the expected result for the input above is:
#    - [ [:credit_card, :phone, :water, :electricity], [], [] ]
#        ^                                             ^   ^
#        +--- paid in full                             |   +- unpaid
#                                  partially paid -----+
#
#  if the budget is 300 the expected result for the input above is:
#    - [ [:credit_card, :phone], [], [:water, :electricity] ]
#        ^                       ^   ^
#        +--- paid in full       |   +- unpaid
#            partially paid -----+
#
#  if the budget is 350 the expected result for the input above is:
#    - [ [:credit_card, :phone], [:water], [:electricity] ]
#        ^                       ^         ^
#        +--- paid in full       |         +- unpaid
#            partially paid -----+
#
#  please note that the smaller the priority value the higher the priority,
#  so bills with priority 0 (the default), must be paid BEFORE bills with priority 1
#  and so on. bills with the same priority must be paid in the order they appear in
#  the input array.

def pay_bills(budget, bills)
  # ...
end

pay_bills_spec.rb

## This spec suite isn't exaustive. For example, it doesn't cover the priority case. You shuold add those examples.

require 'minitest/spec'
require 'minitest/autorun'

require_relative 'pay_bills'

describe '#pay_bills' do
  subject { pay_bills(budget, input) }

  describe 'when budget is enough to pay all bills' do
    let(:budget) { 600 }
    let(:input) do
      [
        { value: 200, type: :water },
        { value: 300, type: :phone },
      ]
    end

    it 'puts everything in the paid array' do
      _(subject).must_equal [
        %i[water phone],
        [],
        []
      ] 
    }
  end

  describe 'when budget is enough to pay exactly some bills' do
    let(:budget) { 500 }
    let(:input) do
      [
        { value: 200, type: :water },
        { value: 300, type: :credit_card },
        { value: 300, type: :phone },
      ]
    end

    it 'puts paid bills in the first array and unpaid in the last' do
      _(subject).must_equal [
        %i[water credit_card],
        [],
        %i[phone]
      ] 
    }
  end

  describe 'when budget is enough to pay some bills and partially others' do
    let(:budget) { 600 }
    let(:input) do
      [
        { value: 200, type: :water },
        { value: 300, type: :credit_card },
        { value: 300, type: :phone },
      ]
    end

    it 'puts paid bills in the first array and partially paid in the second' do
      _(subject).must_equal [
        %i[water credit_card], # completely paid
        %i[phone]              # partially paid
        [],                    # unpaid
      ] 
    }
  end
end