ListingsToolkit refactoring (#16184)

app/controllers/concerns/listings_toolkit.rb

@@ -16,10 +16,7 @@ module ListingsToolkit
     # [@forem/oss] Not entirely sure what the intention behind the
     # original code was, but at least this is more compact.
 
-    # [@forem/oss] Rails 6.1 adds `.compact` on ActionController::Parameters
-    # rubocop:disable Style/CollectionCompact
-    filtered_params = listing_params.reject { |_k, v| v.nil? }
-    # rubocop:enable Style/CollectionCompact
+    filtered_params = listing_params.compact
 
     @listing.update(filtered_params)
   end
@@ -105,29 +102,9 @@ module ListingsToolkit
   end
 
   def create_listing(purchaser, cost)
-    successful_transaction = false
-    ActiveRecord::Base.transaction do
-      # subtract credits
-      Credits::Buyer.call(
-        purchaser: purchaser,
-        purchase: @listing,
-        cost: cost,
-      )
+    create_result = Listings::Create.call(@listing, purchaser: purchaser, cost: cost)
 
-      # save the listing
-      @listing.bumped_at = Time.current
-      @listing.published = true
-      @listing.originally_published_at = Time.current
-
-      # since we can't raise active record errors in this transaction
-      # due to the fact that we need to display them in the :new view,
-      # we manually rollback the transaction if there are validation errors
-      raise ActiveRecord::Rollback unless @listing.save
-
-      successful_transaction = true
-    end
-
-    if successful_transaction
+    if create_result.success?
       rate_limiter.track_limit_by_action(:listing_creation)
       clear_listings_cache
       process_successful_creation

app/services/listings/create.rb

@@ -0,0 +1,50 @@
+module Listings
+  # This service wraps listing purchses in a transaction which verifies that
+  # the purchaser has enough credits to complete this process.
+  class Create
+    # @param listing [Listing] an initialized but not yet persisted listing
+    # @param purchaser [User] the user attempting to purchase the listing
+    # @param cost [Integer] the number of credits the user has to spend
+    # @return [Listings::Create] the service itself, used for the success? check
+    def self.call(listing, purchaser:, cost:)
+      new(listing, purchaser, cost).call
+    end
+
+    def initialize(listing, purchaser, cost)
+      @listing = listing
+      @purchaser = purchaser
+      @cost = cost
+      @success = false
+    end
+
+    def call
+      ActiveRecord::Base.transaction do
+        # Subtract credits
+        enough_credits = Credits::Buyer.call(
+          purchaser: @purchaser,
+          purchase: @listing,
+          cost: @cost,
+        )
+
+        raise ActiveRecord::Rollback unless enough_credits
+
+        # Update the listing
+        @listing.bumped_at = Time.current
+        @listing.published = true
+        @listing.originally_published_at = Time.current
+
+        # Since we can't raise ActiveRecord errors in this transaction
+        # due to the fact that we need to display them in the :new view,
+        # we manually rollback the transaction if there are validation errors
+        raise ActiveRecord::Rollback unless @listing.save
+
+        @success = true
+      end
+      self
+    end
+
+    def success?
+      @success
+    end
+  end
+end

spec/services/listings/create_spec.rb

@@ -0,0 +1,17 @@
+require "rails_helper"
+
+RSpec.describe Listings::Create, type: :service do
+  let(:user) { create(:user) }
+  let(:listing) { build(:listing, user: user) }
+
+  it "is successful when the purchaser has enough credits" do
+    create(:credit, user: user)
+    create_result = described_class.call(listing, purchaser: user, cost: 1)
+    expect(create_result.success?).to be true
+  end
+
+  it "fails if the purchaser doesn't have enough credits" do
+    create_result = described_class.call(listing, purchaser: user, cost: 1)
+    expect(create_result.success?).to be false
+  end
+end