netengine_golf.rb

require 'rspec'
require 'json'
require 'active_support/all'
require 'pry'

def input
  [{:lastmodificationdate=>"2012-12-20T23:26:34Z",
    :totalcost=>30.827698,
    :userproject=>"FCBIZ"},
   {:lastmodificationdate=>"2012-12-20T23:26:34Z",
    :totalcost=>92.440566,
    :userproject=>"FCTA"},
   {:lastmodificationdate=>"2012-12-20T23:26:34Z",
    :totalcost=>9.481353,
    :userproject=>"LMS"},
   {:lastmodificationdate=>"2012-12-20T23:26:34Z",
    :totalcost=>2.700484,
    :userproject=>"adenbrook"},
   {:lastmodificationdate=>"2012-12-20T23:26:34Z",
    :totalcost=>16.837905,
    :userproject=>"healthwise"},
   {:lastmodificationdate=>"2012-12-20T23:26:34Z",
    :totalcost=>3.615383,
    :userproject=>"latronics"},
   {:lastmodificationdate=>"2012-12-20T23:26:34Z",
    :totalcost=>1171.492842,
    :userproject=>"scout"},
   {:lastmodificationdate=>"2012-12-20T23:26:34Z",
    :totalcost=>0.002458,
    :userproject=>"triggerapp"},
   {:lastmodificationdate=>"2012-12-20T23:26:34Z",
    :totalcost=>34.834151,
    :userproject=>nil}]
end

def desired_output
  [{:date=>nil,
  :lastmodificationdate=>"2012-12-20T23:26:34Z",
  :totalcost=>34.834151,
  :userproject=>nil}]
end

class NetEngineGolf
  def jim_1(input)
    input.group_by { |a| a[:date] }.map do |date, values|
      values.inject({}) do |hash, value|
        hash.merge! value
      end
    end
  end

  def jim_2(input)
    input.group_by { |a| a[:date] }.map do |date, values|
      merged = { date: date }
      values.each { |value| merged.merge! value.except(:date) }
      merged
    end
  end
end

describe NetEngineGolf do
  describe "#jim_1" do
    it "turns the input into the output" do
      output = NetEngineGolf.new.jim_1(input)
      output.should == desired_output
    end
  end

  describe "#jim_2" do
    it "turns the input into the output" do
      output = NetEngineGolf.new.jim_2(input)
      output.should == desired_output
    end
  end
end