use short-form presence validator.

use two-argument form.
add unpaid scope.
repair tests.

app/controllers/conference_registrations_controller.rb

@@ -28,7 +28,7 @@ class ConferenceRegistrationsController < ApplicationController
   end
 
   def show
-    @total_price = Ticket.total_price(@conference, current_user, :paid => true)
+    @total_price = Ticket.total_price(@conference, current_user, paid: true)
     @tickets = current_user.ticket_purchases.where(conference_id: @conference.id, paid: true)
     @ticket_payments = @tickets.group_by(&:payment_id)
   end

app/controllers/ticket_purchases_controller.rb

@@ -7,7 +7,7 @@ class TicketPurchasesController < ApplicationController
     TicketPurchase.destroy_all(user_id: current_user.id, conference_id: @conference.id, paid: false)
     message = TicketPurchase.purchase(@conference, current_user, params[:tickets][0])
     if message.blank?
-      if current_user.ticket_purchases.where(paid: false).any?
+      if current_user.ticket_purchases.unpaid.any?
         redirect_to new_conference_payment_path, notice: 'Please pay here to purchase tickets.'
       else
         redirect_to conference_conference_registration_path(@conference.short_title)

app/models/ticket.rb

@@ -21,8 +21,8 @@ class Ticket < ActiveRecord::Base
     ticket_purchases.find_by(user: user, paid: true).present?
   end
 
-  def quantity_bought_by(user, hashed_paid)
-   purchased_tickets = ticket_purchases.where(user_id: user.id, paid: hashed_paid[:paid])
+  def quantity_bought_by(user, paid: false)
+    purchased_tickets = ticket_purchases.where(user_id: user.id, paid: paid)
     quantity = 0
     if purchased_tickets
       purchased_tickets.each do |ticket|
@@ -36,16 +36,16 @@ class Ticket < ActiveRecord::Base
     ticket_purchases.find_by(user: user, paid: false).present?
   end
 
-  def total_price(user, hashed_paid)
-    quantity_bought_by(user, hashed_paid) * price
+  def total_price(user, paid: false)
+    quantity_bought_by(user, paid: paid) * price
   end
 
-  def self.total_price(conference, user, hashed_paid)
+  def self.total_price(conference, user, paid: false)
     tickets = Ticket.where(conference_id: conference.id)
     result = nil
     begin
       tickets.each do |ticket|
-        price = ticket.total_price(user, hashed_paid)
+        price = ticket.total_price(user, paid: paid)
         if result
           result +=  price unless price.zero?
         else

app/models/ticket_purchase.rb

@@ -13,6 +13,8 @@ class TicketPurchase < ActiveRecord::Base
   delegate :price_cents, to: :ticket
   delegate :price_currency, to: :ticket
 
+  scope :unpaid, -> { where(paid: false) }
+
   def self.purchase(conference, user, purchases)
     errors = []
     ActiveRecord::Base.transaction do

spec/models/payment_spec.rb

@@ -7,33 +7,19 @@ describe Payment do
       expect(build(:payment)).to be_valid
     end
 
-    it 'is not valid without a first_name' do
-      should validate_presence_of(:first_name)
-    end
+    it { is_expected.to validate_presence_of(:first_name) }
 
-    it 'is not valid without a last_name' do
-      should validate_presence_of(:last_name)
-    end
+    it { is_expected.to validate_presence_of(:last_name) }
 
-    it 'is not valid without a credit_card_number' do
-      should validate_presence_of(:credit_card_number)
-    end
+    it { is_expected.to validate_presence_of(:credit_card_number) }
 
-    it 'is not valid without a card_verification_value' do
-      should validate_presence_of(:card_verification_value)
-    end
+    it { is_expected.to validate_presence_of(:card_verification_value) }
 
-    it 'is not valid without a expiration_month' do
-      should validate_presence_of(:expiration_month)
-    end
+    it { is_expected.to validate_presence_of(:expiration_month) }
 
-    it 'is not valid without a expiration_year' do
-      should validate_presence_of(:expiration_year)
-    end
+    it { is_expected.to validate_presence_of(:expiration_year) }
 
-    it 'is not valid without a amount' do
-      should validate_presence_of(:amount)
-    end
+    it { is_expected.to validate_presence_of(:amount) }
 
     it 'is not valid with a amount equals zero' do
       should_not allow_value(0).for(:amount)

spec/models/ticket_spec.rb

@@ -108,11 +108,11 @@ describe Ticket do
              user: user,
              ticket: ticket,
              quantity: 20)
-      expect(ticket.quantity_bought_by(user, :paid => false)).to eq(20)
+      expect(ticket.quantity_bought_by(user, paid: false)).to eq(20)
     end
 
     it 'returns zero if the user has not bought this ticket' do
-      expect(ticket.quantity_bought_by(user, :paid => false)).to eq(0)
+      expect(ticket.quantity_bought_by(user, paid: false)).to eq(0)
     end
   end
 
@@ -122,11 +122,11 @@ describe Ticket do
              user: user,
              ticket: ticket,
              quantity: 20)
-      expect(ticket.total_price(user, :paid => false)).to eq(Money.new(100000, 'USD'))
+      expect(ticket.total_price(user, paid: false)).to eq(Money.new(100000, 'USD'))
     end
 
     it 'returns zero if the user has not bought this ticket' do
-      expect(ticket.total_price(user, :paid => false)).to eq(Money.new(0, 'USD'))
+      expect(ticket.total_price(user, paid: false)).to eq(Money.new(0, 'USD'))
     end
   end
 
@@ -136,7 +136,7 @@ describe Ticket do
     describe 'user has bought' do
       context 'no tickets' do
         it 'returns zero' do
-          expect(Ticket.total_price(conference, user, :paid => false)).to eq(Money.new(0, 'USD'))
+          expect(Ticket.total_price(conference, user, paid: false)).to eq(Money.new(0, 'USD'))
         end
       end
 
@@ -146,7 +146,7 @@ describe Ticket do
         end
 
         it 'returns the correct total price' do
-          expect(Ticket.total_price(conference, user, :paid => false)).to eq(Money.new(100000, 'USD'))
+          expect(Ticket.total_price(conference, user, paid: false)).to eq(Money.new(100000, 'USD'))
         end
       end
 
@@ -158,7 +158,7 @@ describe Ticket do
 
         it 'returns the correct total price' do
           total_price = Money.new(200000, 'USD')
-          expect(Ticket.total_price(conference, user, :paid => false)).to eq(total_price)
+          expect(Ticket.total_price(conference, user, paid: false)).to eq(total_price)
         end
       end
     end