Fixs add coupon to offer

app/controllers/checkouts_controller.rb

@@ -23,7 +23,7 @@ def create
                             payment_method_id: params[:payment_method_id],
                             offer: @offer,
                             coupon: @coupon,
-                            amount: params[:amount],
+                            amount: params[:amount] || 0,
                             invoice: @invoice)
 
     message = checkout.pay

app/models/coupon.rb

@@ -17,7 +17,7 @@ class Coupon < ApplicationRecord
 
   def discounted_price
     return amount_off if amount_off
-    offer.amount * percent_off
+    offer.amount * (percent_off / 100.to_d)
   end
 
   private

app/models/invoice.rb

@@ -16,7 +16,7 @@ class Invoice < ApplicationRecord
   validates :due_on, presence: true
 
   def status
-    return status_for_not_offering if offer.amount
+    return status_for_not_offering if offer.amount?
     status_for_offering
   end
 

app/models/offer.rb

@@ -20,4 +20,8 @@ class Offer < ApplicationRecord
   validates :manager, presence: true
   validates :name, presence: true
   validates :description, presence: true
+
+  def amount
+    amount? ? attributes['amount'] : 0
+  end
 end

app/views/checkouts/_coupon_form.html.haml

@@ -1,8 +1,9 @@
-= form_tag(checkouts_path, class: "pure-form") do
-  %fieldset
-    .pure-u-1-4
-      %h5 Coupon
-      = text_field_tag :coupon,nil, {class: "pure-input-1-4"}
-      = hidden_field_tag :offer_id, @offer.id
-      = hidden_field_tag :invoice_id, @invoice.id
-      %button.pure-button{type: "submit"} Apply Coupon
+- if @offer.amount?
+  = form_tag(checkouts_path, class: "pure-form") do
+    %fieldset
+      .pure-u-1-4
+        %h5 Coupon
+        = text_field_tag :coupon,nil, {class: "pure-input-1-4"}
+        = hidden_field_tag :offer_id, @offer.id
+        = hidden_field_tag :invoice_id, @invoice.id
+        %button.pure-button{type: "submit"} Apply Coupon

app/views/checkouts/_make_payment_form.html.haml

@@ -2,7 +2,7 @@
   %fieldset
     %div.pure-u-1-4
       %h5 Payment
-      - if @offer.deferrable? && @offer.amount
+      - if @offer.deferrable? && @offer.amount?
         = number_field_tag :amount, format_amount(@balance_remaining), {min: 0.00, max: @balance_remaining, step: :any, class: "pure-input-1-4"}
       - else
         = hidden_field_tag :amount, @balance_remaining

features/applying_a_coupon.feature

@@ -64,3 +64,16 @@ Feature: Applying a Coupon
     And I click Apply Coupon
     Then I should be redirected to the Invoice page
     And I should see a message saying I can't apply a coupon after made a payment
+
+  Scenario: User can't use coupons on offers without amounts
+    Given I am logged in
+    And I am on an offer page without amount
+    Then I click on the Purchase link
+    And I should not see the apply coupon button
+
+  Scenario: User can use coupons on deferrable offers
+    Given I am logged in
+    And I am on an offer page
+    Then I click on the Purchase link
+    And I have a valid coupon code
+    And I should see the apply coupon button

features/steps/common_steps/pages.rb

@@ -9,6 +9,13 @@ module Pages
       expect(page).to have_content(offer_name)
     end
 
+    step 'I am on an offer page without amount' do
+      offer_name = 'Offer Name'
+      offer = FactoryGirl.create(:offer, name: offer_name, id: 1, due_on: Time.zone.now + 3.days, deferrable: true, amount: nil)
+      visit "/offers/1?public_token=#{offer.manager.public_token}"
+      expect(page).to have_content(offer_name)
+    end
+
     step 'I am on an offer page for an offer that doesn\'t have an amount' do
       offer_name = 'Offer Name'
       offer = FactoryGirl.create(:offer, name: offer_name, id: 1, amount: nil, due_on: Time.zone.now + 3.days, deferrable: true)

spec/models/coupon_spec.rb

@@ -42,7 +42,7 @@
     context 'when offer has percent off' do
       let(:coupon) { FactoryGirl.create(:coupon, amount_off: nil, percent_off: 0.2) }
       it 'returns the offer amount * percent off as a discount price' do
-        expect(coupon.discounted_price).to eq 20
+        expect(coupon.discounted_price).to eq 0.2
       end
     end
   end