fix: inefficient SQL loading latest verification for pact version

Closes: pact-foundation#291

Author: bethesque

lib/pact_broker/pacts/pact_version.rb

@@ -1,12 +1,14 @@
 require 'sequel'
 require 'pact_broker/repositories/helpers'
+require 'pact_broker/verifications/latest_verification_for_pact_version'
 
 module PactBroker
   module Pacts
     class PactVersion < Sequel::Model(:pact_versions)
       plugin :timestamps
       one_to_many :pact_publications, reciprocal: :pact_version
       one_to_many :verifications, reciprocal: :verification, order: :id, :class => "PactBroker::Domain::Verification"
+      one_to_one :latest_verification, class: "PactBroker::Verifications::LatestVerificationForPactVersion", key: :pact_version_id, primary_key: :id
       associate(:many_to_one, :provider, class: "PactBroker::Domain::Pacticipant", key: :provider_id, primary_key: :id)
       associate(:many_to_one, :consumer, class: "PactBroker::Domain::Pacticipant", key: :consumer_id, primary_key: :id)
 
@@ -40,10 +42,6 @@ def latest_pact_publication
           .last
       end
 
-      def latest_verification
-        verifications.last
-      end
-
       def consumer_versions
         PactBroker::Domain::Version.where(id: PactBroker::Pacts::PactPublication.select(:consumer_version_id).where(pact_version_id: id)).order(:order)
       end

spec/lib/pact_broker/pacts/pact_version_spec.rb

@@ -92,6 +92,22 @@ module Pacts
           expect(PactVersion.first.latest_consumer_version_number).to eq "1.0.1"
         end
       end
+
+      describe "#latest_verification" do
+        before do
+          td.create_pact_with_hierarchy
+            .create_verification
+            .create_verification(number: 2)
+            .create_verification(number: 3)
+        end
+        let(:pact_version) { PactVersion.last }
+
+        subject { pact_version.latest_verification }
+
+        it "returns the latest verification by execution date" do
+          expect(subject.number).to eq 3
+        end
+      end
     end
   end
 end