some automated tests about cash coupons

app/services/coupon_apply_service.rb

@@ -12,13 +12,14 @@ class CouponApplyService
   def call(total, coupon, user_id = nil)
     price = total
 
+    _coupon = nil
     if coupon.instance_of? Coupon
       _coupon = coupon
     elsif coupon.instance_of? String
       _coupon = Coupon.find_by(code: coupon)
     end
 
-    unless coupon.nil?
+    unless _coupon.nil?
       if _coupon.status(user_id, total) == 'active'
         if _coupon.type == 'percent_off'
           price = price - (price * _coupon.percent_off / 100.0)

test/fixtures/coupons.yml

@@ -17,3 +17,12 @@ two:
   max_usages: 10
   active: true
   validity_per_user: always
+
+cash:
+  name: Cash Code
+  code: ZERG6H1R65H
+  amount_off: 10000
+  valid_until: <%= 1.year.from_now.utc.strftime('%Y-%m-%d %H:%M:%S.%9N Z') %>
+  max_usages: 1
+  active: true
+  validity_per_user: once

test/models/coupon_test.rb

@@ -8,11 +8,21 @@ class CouponTest < ActiveSupport::TestCase
 
   test 'expired coupon must return the proper status' do
     c = Coupon.find_by(code: 'XMAS10')
-    assert c.status == 'expired'
+    assert_equal 'expired', c.status
   end
 
   test 'two coupons cannot have the same code' do
     c = Coupon.new({name: 'Summer deals', code: 'SUNNYFABLAB', percent_off: 15, validity_per_user: 'always'})
     assert c.invalid?
   end
+
+  test 'coupon with cash amount has amount_off type' do
+    c = Coupon.new({name: 'Essential Box', code: 'KWXX2M', amount_off: 2000, validity_per_user: 'once', max_usages: 1})
+    assert_equal 'amount_off', c.type
+  end
+
+  test 'coupon with cash amount cannot be used with cheaper cart' do
+    c = Coupon.new({name: 'Premium Box', code: '6DDX2T44MQ', amount_off: 20000, validity_per_user: 'once', max_usages: 1, active: true})
+    assert_equal 'amount_exceeded', c.status(User.find_by(username: 'jdupond').id, 2000)
+  end
 end

test/services/coupon_apply_service_test.rb

@@ -0,0 +1,28 @@
+require 'test_helper'
+
+class CouponApplyServiceTest < ActiveSupport::TestCase
+  setup do
+    @jdupond = User.find_by(username: 'jdupond')
+    @cash_coupon = Coupon.find_by(code: 'ZERG6H1R65H')
+  end
+
+  test 'user apply percent coupon to cart' do
+    total = CouponApplyService.new.(1000, 'SUNNYFABLAB', @jdupond.id)
+    assert_equal 850, total
+  end
+
+  test 'user cannot apply excessive coupon to cart' do
+    total = CouponApplyService.new.(1000, @cash_coupon, @jdupond.id)
+    assert_equal 1000, total
+  end
+
+  test 'user cannot apply invalid coupon to cart' do
+    total = CouponApplyService.new.(1000, 'INVALIDCODE', @jdupond.id)
+    assert_equal 1000, total
+  end
+
+  test 'user cannot apply expired coupon to cart' do
+    total = CouponApplyService.new.(1000, 'XMAS10', @jdupond.id)
+    assert_equal 1000, total
+  end
+end