diff --git a/api/spec/features/checkout_spec.rb b/api/spec/features/checkout_spec.rb
index f8638177fe0..21af915ed69 100644
--- a/api/spec/features/checkout_spec.rb
+++ b/api/spec/features/checkout_spec.rb
@@ -7,8 +7,6 @@ module Spree
     before do
       stub_spree_preferences(Spree::Api::Config, requires_authentication: false)
     end
-    let!(:promotion) { FactoryBot.create(:promotion, :with_order_adjustment, code: 'foo', weighted_order_adjustment_amount: 10) }
-    let(:promotion_code) { promotion.codes.first }
     let!(:store) { FactoryBot.create(:store) }
     let(:bill_address) { FactoryBot.create(:address) }
     let(:ship_address) { FactoryBot.create(:address) }
@@ -62,14 +60,6 @@ def create_line_item(variant, quantity = 1)
       expect(response).to have_http_status(:created)
     end
 
-    def add_promotion(_promotion)
-      expect {
-        post "/api/orders/#{@order.number}/coupon_codes",
-          params: { coupon_code: promotion_code.value }
-      }.to change { @order.promotions.count }.by 1
-      expect(response).to have_http_status(:ok)
-    end
-
     def add_address(address, billing: true)
       address_type = billing ? :bill_address : :ship_address
       # It seems we are missing an order-scoped address api endpoint since we need
@@ -103,8 +93,8 @@ def assert_order_expectations
       expect(@order.state).to eq 'complete'
       expect(@order.completed_at).to be_a ActiveSupport::TimeWithZone
       expect(@order.item_total).to eq 600.00
-      expect(@order.total).to eq 600.00
-      expect(@order.adjustment_total).to eq(-10.00)
+      expect(@order.total).to eq 610.00
+      expect(@order.adjustment_total).to eq(0)
       expect(@order.shipment_total).to eq 10.00
       expect(@order.user).to eq @user
       expect(@order.bill_address).to eq bill_address
@@ -112,7 +102,6 @@ def assert_order_expectations
       expect(@order.payments.length).to eq 1
       expect(@order.line_items.any? { |li| li.variant == variant_1 && li.quantity == 2 }).to eq true
       expect(@order.line_items.any? { |li| li.variant == variant_2 && li.quantity == 2 }).to eq true
-      expect(@order.promotions).to eq [promotion]
     end
 
     it "is able to checkout with individualized requests" do
@@ -120,7 +109,6 @@ def assert_order_expectations
       create_order
 
       create_line_item(variant_1, 2)
-      add_promotion(promotion)
       create_line_item(variant_2, 2)
 
       add_address(bill_address)
@@ -152,7 +140,6 @@ def assert_order_expectations
         }
       })
 
-      add_promotion(promotion)
       add_payment
 
       advance
@@ -180,7 +167,6 @@ def assert_order_expectations
         }
       })
 
-      add_promotion(promotion)
       add_payment
 
       advance
diff --git a/api/spec/requests/spree/api/coupon_codes_spec.rb b/api/spec/requests/spree/api/coupon_codes_spec.rb
index c7324d9c58d..993d5852422 100644
--- a/api/spec/requests/spree/api/coupon_codes_spec.rb
+++ b/api/spec/requests/spree/api/coupon_codes_spec.rb
@@ -132,7 +132,6 @@ module Spree::Api
           subject
 
           expect(response.status).to eq(422)
-          expect(order.reload.promotions).to eq([])
           expect(json_response).to eq({
             "success" => nil,
             "error" => I18n.t('spree.coupon_code_not_present'),
diff --git a/api/spec/requests/spree/api/promotion_application_spec.rb b/api/spec/requests/spree/api/promotion_application_spec.rb
deleted file mode 100644
index bda24996eb6..00000000000
--- a/api/spec/requests/spree/api/promotion_application_spec.rb
+++ /dev/null
@@ -1,50 +0,0 @@
-# frozen_string_literal: true
-
-require 'spec_helper'
-
-module Spree::Api
-  describe 'Promotion application', type: :request do
-    before do
-      stub_authentication!
-    end
-
-    context "with an available promotion" do
-      let!(:order) { create(:order_with_line_items, line_items_count: 1) }
-      let!(:promotion) do
-        promotion = create(:promotion, name: "10% off", code: "10off")
-        calculator = Spree::Calculator::FlatPercentItemTotal.create(preferred_flat_percent: "10")
-        action = Spree::Promotion::Actions::CreateItemAdjustments.create(calculator: calculator)
-        promotion.actions << action
-        promotion
-      end
-
-      it "can apply a coupon code to the order" do
-        expect(order.total).to eq(110.00)
-        post spree.api_order_coupon_codes_path(order), params: { coupon_code: "10off", order_token: order.guest_token }
-        expect(response.status).to eq(200)
-        expect(order.reload.total).to eq(109.00)
-        expect(json_response["success"]).to eq("The coupon code was successfully applied to your order.")
-        expect(json_response["error"]).to be_blank
-        expect(json_response["successful"]).to be true
-        expect(json_response["status_code"]).to eq("coupon_code_applied")
-      end
-
-      context "with an expired promotion" do
-        before do
-          promotion.starts_at = 2.weeks.ago
-          promotion.expires_at = 1.week.ago
-          promotion.save
-        end
-
-        it "fails to apply" do
-          post spree.api_order_coupon_codes_path(order), params: { coupon_code: "10off", order_token: order.guest_token }
-          expect(response.status).to eq(422)
-          expect(json_response["success"]).to be_blank
-          expect(json_response["error"]).to eq("The coupon code is expired")
-          expect(json_response["successful"]).to be false
-          expect(json_response["status_code"]).to eq("coupon_code_expired")
-        end
-      end
-    end
-  end
-end
diff --git a/legacy_promotions/lib/solidus_legacy_promotions.rb b/legacy_promotions/lib/solidus_legacy_promotions.rb
index 3f5857cad20..11e190aa6e5 100644
--- a/legacy_promotions/lib/solidus_legacy_promotions.rb
+++ b/legacy_promotions/lib/solidus_legacy_promotions.rb
@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "solidus_core"
+require "solidus_api"
 require "solidus_support"
 
 module SolidusLegacyPromotions
diff --git a/legacy_promotions/solidus_legacy_promotions.gemspec b/legacy_promotions/solidus_legacy_promotions.gemspec
index 778d9fc367f..a31c951abd4 100644
--- a/legacy_promotions/solidus_legacy_promotions.gemspec
+++ b/legacy_promotions/solidus_legacy_promotions.gemspec
@@ -24,5 +24,6 @@ Gem::Specification.new do |s|
   s.required_rubygems_version = '>= 1.8.23'
 
   s.add_dependency 'solidus_core', s.version
+  s.add_dependency 'solidus_api', s.version
   s.add_dependency 'solidus_support'
 end
diff --git a/legacy_promotions/spec/features/api/checkout_spec.rb b/legacy_promotions/spec/features/api/checkout_spec.rb
new file mode 100644
index 00000000000..3455f07d366
--- /dev/null
+++ b/legacy_promotions/spec/features/api/checkout_spec.rb
@@ -0,0 +1,192 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+module Spree
+  RSpec.describe 'Api Feature Specs', type: :request do
+    before do
+      stub_spree_preferences(Spree::Api::Config, requires_authentication: false)
+    end
+    let!(:promotion) { FactoryBot.create(:promotion, :with_order_adjustment, code: 'foo', weighted_order_adjustment_amount: 10) }
+    let(:promotion_code) { promotion.codes.first }
+    let!(:store) { FactoryBot.create(:store) }
+    let(:bill_address) { FactoryBot.create(:address) }
+    let(:ship_address) { FactoryBot.create(:address) }
+    let(:variant_1) { FactoryBot.create(:variant, price: 100.00) }
+    let(:variant_2) { FactoryBot.create(:variant, price: 200.00) }
+    let(:payment_method) { FactoryBot.create(:check_payment_method) }
+    let!(:shipping_method) do
+      FactoryBot.create(:shipping_method).tap do |shipping_method|
+        shipping_method.zones.first.zone_members.create!(zoneable: ship_address.country)
+        shipping_method.calculator.set_preference(:amount, 10.0)
+      end
+    end
+
+    def parsed
+      JSON.parse(response.body)
+    end
+
+    def login
+      expect {
+        post '/api/users', params: {
+          user: {
+            email: "featurecheckoutuser@example.com",
+            password: "featurecheckoutuser"
+          }
+        }
+      }.to change { Spree.user_class.count }.by 1
+      expect(response).to have_http_status(:created)
+      @user = Spree.user_class.find(parsed['id'])
+
+      # copied from api testing helpers support since we can't really sign in
+      allow(Spree::LegacyUser).to receive(:find_by).with(hash_including(:spree_api_key)) { @user }
+    end
+
+    def create_order(order_params: {})
+      expect { post '/api/orders', params: order_params }.to change { Order.count }.by 1
+      expect(response).to have_http_status(:created)
+      @order = Order.find(parsed['id'])
+      expect(@order.email).to eq "featurecheckoutuser@example.com"
+    end
+
+    def update_order(order_params: {})
+      put "/api/orders/#{@order.number}", params: order_params
+      expect(response).to have_http_status(:ok)
+    end
+
+    def create_line_item(variant, quantity = 1)
+      expect {
+        post "/api/orders/#{@order.number}/line_items",
+          params: { line_item: { variant_id: variant.id, quantity: quantity } }
+      }.to change { @order.line_items.count }.by 1
+      expect(response).to have_http_status(:created)
+    end
+
+    def add_promotion(_promotion)
+      expect {
+        post "/api/orders/#{@order.number}/coupon_codes",
+          params: { coupon_code: promotion_code.value }
+      }.to change { @order.promotions.count }.by 1
+      expect(response).to have_http_status(:ok)
+    end
+
+    def add_address(address, billing: true)
+      address_type = billing ? :bill_address : :ship_address
+      # It seems we are missing an order-scoped address api endpoint since we need
+      # to use update here.
+      expect {
+        update_order(order_params: { order: { address_type => address.as_json.except('id') } })
+      }.to change { @order.reload.public_send(address_type) }.to address
+    end
+
+    def add_payment
+      expect {
+        post "/api/orders/#{@order.number}/payments",
+          params: { payment: { payment_method_id: payment_method.id } }
+      }.to change { @order.reload.payments.count }.by 1
+      expect(response).to have_http_status(:created)
+      expect(@order.payments.last.payment_method).to eq payment_method
+    end
+
+    def advance
+      put "/api/checkouts/#{@order.number}/advance"
+      expect(response).to have_http_status(:ok)
+    end
+
+    def complete
+      put "/api/checkouts/#{@order.number}/complete"
+      expect(response).to have_http_status(:ok)
+    end
+
+    def assert_order_expectations
+      @order.reload
+      expect(@order.state).to eq 'complete'
+      expect(@order.completed_at).to be_a ActiveSupport::TimeWithZone
+      expect(@order.item_total).to eq 600.00
+      expect(@order.total).to eq 600.00
+      expect(@order.adjustment_total).to eq(-10.00)
+      expect(@order.shipment_total).to eq 10.00
+      expect(@order.user).to eq @user
+      expect(@order.bill_address).to eq bill_address
+      expect(@order.ship_address).to eq ship_address
+      expect(@order.payments.length).to eq 1
+      expect(@order.line_items.any? { |li| li.variant == variant_1 && li.quantity == 2 }).to eq true
+      expect(@order.line_items.any? { |li| li.variant == variant_2 && li.quantity == 2 }).to eq true
+      expect(@order.promotions).to eq [promotion]
+    end
+
+    it "is able to checkout with individualized requests" do
+      login
+      create_order
+
+      create_line_item(variant_1, 2)
+      add_promotion(promotion)
+      create_line_item(variant_2, 2)
+
+      add_address(bill_address)
+      add_address(ship_address, billing: false)
+
+      add_payment
+
+      advance
+      complete
+
+      assert_order_expectations
+    end
+
+    it "is able to checkout with the create request" do
+      login
+
+      create_order(order_params: {
+        order: {
+          bill_address: bill_address.as_json.except('id'),
+          ship_address: ship_address.as_json.except('id'),
+          line_items: {
+            0 => { variant_id: variant_1.id, quantity: 2 },
+            1 => { variant_id: variant_2.id, quantity: 2 }
+          },
+          # Would like to do this, but it puts the payment in a complete state,
+          # which the order does not like when transitioning from confirm to complete
+          # since it looks to process pending payments.
+          # payments: [ { payment_method: payment_method.name, state: "pending" } ],
+        }
+      })
+
+      add_promotion(promotion)
+      add_payment
+
+      advance
+      complete
+
+      assert_order_expectations
+    end
+
+    it "is able to checkout with the update request" do
+      login
+
+      create_order
+      update_order(order_params: {
+        order: {
+          bill_address: bill_address.as_json.except('id'),
+          ship_address: ship_address.as_json.except('id'),
+          line_items: {
+            0 => { variant_id: variant_1.id, quantity: 2 },
+            1 => { variant_id: variant_2.id, quantity: 2 }
+          },
+          # Would like to do this, but it puts the payment in a complete state,
+          # which the order does not like when transitioning from confirm to complete
+          # since it looks to process pending payments.
+          # payments: [ { payment_method: payment_method.name, state: "pending" } ],
+        }
+      })
+
+      add_promotion(promotion)
+      add_payment
+
+      advance
+      complete
+
+      assert_order_expectations
+    end
+  end
+end
diff --git a/legacy_promotions/spec/rails_helper.rb b/legacy_promotions/spec/rails_helper.rb
index c86a7eba5e9..f8a29a778bb 100644
--- a/legacy_promotions/spec/rails_helper.rb
+++ b/legacy_promotions/spec/rails_helper.rb
@@ -20,6 +20,7 @@
 require 'spree/testing_support/preferences'
 require 'spree/testing_support/rake'
 require 'spree/testing_support/job_helpers'
+require 'spree/api/testing_support/helpers'
 require 'cancan/matchers'
 
 ActiveJob::Base.queue_adapter = :test
@@ -48,4 +49,5 @@
   config.include Spree::TestingSupport::JobHelpers
 
   config.include FactoryBot::Syntax::Methods
+  config.include Spree::Api::TestingSupport::Helpers, type: :request
 end
diff --git a/legacy_promotions/spec/requests/spree/api/promotion_application_spec.rb b/legacy_promotions/spec/requests/spree/api/promotion_application_spec.rb
new file mode 100644
index 00000000000..eeb618d13ce
--- /dev/null
+++ b/legacy_promotions/spec/requests/spree/api/promotion_application_spec.rb
@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe 'Promotion application', type: :request do
+  before do
+    stub_authentication!
+  end
+
+  context "with an available promotion" do
+    let!(:order) { create(:order_with_line_items, line_items_count: 1) }
+    let!(:promotion) do
+      promotion = create(:promotion, name: "10% off", code: "10off")
+      calculator = Spree::Calculator::FlatPercentItemTotal.create(preferred_flat_percent: "10")
+      action = Spree::Promotion::Actions::CreateItemAdjustments.create(calculator: calculator)
+      promotion.actions << action
+      promotion
+    end
+
+    it "can apply a coupon code to the order" do
+      expect(order.total).to eq(110.00)
+      post spree.api_order_coupon_codes_path(order), params: { coupon_code: "10off", order_token: order.guest_token }
+      expect(response.status).to eq(200)
+      expect(order.reload.total).to eq(109.00)
+      expect(json_response["success"]).to eq("The coupon code was successfully applied to your order.")
+      expect(json_response["error"]).to be_blank
+      expect(json_response["successful"]).to be true
+      expect(json_response["status_code"]).to eq("coupon_code_applied")
+    end
+
+    context "with an expired promotion" do
+      before do
+        promotion.starts_at = 2.weeks.ago
+        promotion.expires_at = 1.week.ago
+        promotion.save
+      end
+
+      it "fails to apply" do
+        post spree.api_order_coupon_codes_path(order), params: { coupon_code: "10off", order_token: order.guest_token }
+        expect(response.status).to eq(422)
+        expect(json_response["success"]).to be_blank
+        expect(json_response["error"]).to eq("The coupon code is expired")
+        expect(json_response["successful"]).to be false
+        expect(json_response["status_code"]).to eq("coupon_code_expired")
+      end
+    end
+  end
+end