add Offer lifecycle guards, more Offer tests

Author: porbas

ecommerce/pricing/lib/pricing/offer.rb

@@ -2,6 +2,7 @@ module Pricing
   class Offer
     include AggregateRoot
 
+    InvalidState = Class.new(StandardError)
     IsEmpty = Class.new(StandardError)
 
     def initialize(id)
@@ -129,6 +130,7 @@ def use_coupon(coupon_id, discount)
 
     def accept
       raise IsEmpty if @list.products.empty?
+      raise InvalidState.new("Only draft offer can be accepted") unless @state == :draft
       apply OfferAccepted.new(
         data: {
           order_id: @id,
@@ -138,10 +140,12 @@ def accept
     end
 
     def reject
+      raise InvalidState.new("Only accepted offer can be rejected") unless @state == :accepted
       apply OfferRejected.new(data: { order_id: @id })
     end
 
     def expire
+      raise InvalidState.new("Only draft offer can be expired") unless @state == :draft
       apply OfferExpired.new(data: { order_id: @id })
     end
 

ecommerce/pricing/test/offer_lifecycle_test.rb

@@ -0,0 +1,130 @@
+require_relative 'test_helper'
+
+module Pricing
+  class OfferLifecycleTest < Test
+    cover "Pricing*"
+
+    def test_accept_draft_offer
+      product_id = SecureRandom.uuid
+      order_id = SecureRandom.uuid
+
+      set_price(product_id, 33)
+      add_item(order_id, product_id)
+      stream = "Pricing::Offer$#{order_id}"
+
+      assert_events(
+        stream,
+        OfferAccepted.new(
+          data: {
+            order_id: order_id,
+            order_lines: [
+              { product_id:, quantity: 1 },
+            ]
+          }
+        )
+      ) { accept_offer(order_id) }
+    end
+
+    def test_empty_offer_cant_be_accepted
+      order_id = SecureRandom.uuid
+
+      assert_raises(Pricing::Offer::IsEmpty) do
+        accept_offer(order_id)
+      end
+    end
+
+    def test_accepted_offer_can_be_rejected
+      product_id = SecureRandom.uuid
+      order_id = SecureRandom.uuid
+
+      set_price(product_id, 33)
+      add_item(order_id, product_id)
+      accept_offer(order_id)
+      stream = "Pricing::Offer$#{order_id}"
+
+
+      assert_events(
+        stream,
+        OfferRejected.new(
+          data: {
+            order_id: order_id,
+          }
+        )
+      ) { reject_offer(order_id) }
+
+    end
+
+    def test_draft_offer_cant_be_rejected
+      product_id = SecureRandom.uuid
+      order_id = SecureRandom.uuid
+
+      set_price(product_id, 33)
+      add_item(order_id, product_id)
+
+      exp = assert_raises(Pricing::Offer::InvalidState, "Only accepted offer can be rejected") do
+        reject_offer(order_id)
+      end
+      assert_equal("Only accepted offer can be rejected", exp.message)
+    end
+
+    def test_draft_offer_can_be_expired
+      product_id = SecureRandom.uuid
+      order_id = SecureRandom.uuid
+
+      set_price(product_id, 33)
+      add_item(order_id, product_id)
+      stream = "Pricing::Offer$#{order_id}"
+
+      assert_events(
+        stream,
+        OfferExpired.new(
+          data: {
+            order_id: order_id,
+          }
+        )
+      ) { expire_offer(order_id) }
+    end
+
+    def test_accepted_offer_cant_be_expired
+      product_id = SecureRandom.uuid
+      order_id = SecureRandom.uuid
+
+      set_price(product_id, 33)
+      add_item(order_id, product_id)
+      accept_offer(order_id)
+
+      exp = assert_raises(Pricing::Offer::InvalidState) do
+        expire_offer(order_id)
+      end
+      assert_equal("Only draft offer can be expired", exp.message)
+    end
+
+    def test_only_draft_offer_can_be_accepted
+      product_id = SecureRandom.uuid
+      order_id = SecureRandom.uuid
+
+      set_price(product_id, 33)
+      add_item(order_id, product_id)
+      accept_offer(order_id)
+
+      exp = assert_raises(Pricing::Offer::InvalidState) do
+        accept_offer(order_id)
+      end
+      assert_equal("Only draft offer can be accepted", exp.message)
+    end
+
+    private
+
+    def accept_offer(order_id)
+      run_command(AcceptOffer.new(order_id:))
+    end
+
+    def reject_offer(order_id)
+      run_command(RejectOffer.new(order_id:))
+    end
+
+    def expire_offer(order_id)
+      run_command(ExpireOffer.new(order_id:))
+    end
+  end
+end