feat(badges): use simple in-memory cache for badges

lib/pact_broker/api/resources/badge.rb

@@ -31,7 +31,7 @@ def forbidden?
         private
 
         def to_svg
-          badges_service.pact_verification_badge pact, label, initials, verification_status
+          badge_service.pact_verification_badge pact, label, initials, verification_status
         end
 
         def pact

lib/pact_broker/badges/cached_service.rb

@@ -0,0 +1,27 @@
+require 'pact_broker/logging'
+require 'pact_broker/badges/service'
+
+module PactBroker
+  module Badges
+    module CachedService
+
+      extend self
+      include PactBroker::Logging
+      extend PactBroker::Services
+
+      CACHE = {}
+      private_constant :CACHE
+
+      def pact_verification_badge pact, label, initials, verification_status
+        badge_key = key(pact, label, initials, verification_status)
+        CACHE[badge_key] ||= PactBroker::Badges::Service.pact_verification_badge(pact, label, initials, verification_status)
+      end
+
+      private
+
+      def key pact, label, initials, verification_status
+        "#{pact.consumer.name}-#{pact.provider.name}-#{label}-#{initials}-#{verification_status}"
+      end
+    end
+  end
+end

lib/pact_broker/services.rb

@@ -42,9 +42,9 @@ def verification_service
       Verifications::Service
     end
 
-    def badges_service
-      require 'pact_broker/badges/service'
-      Badges::Service
+    def badge_service
+      require 'pact_broker/badges/cached_service'
+      Badges::CachedService
     end
   end
 end

spec/lib/pact_broker/badges/cached_service_spec.rb

@@ -0,0 +1,49 @@
+require 'pact_broker/badges/cached_service'
+require 'pact_broker/badges/service'
+
+module PactBroker
+  module Badges
+    describe CachedService do
+
+      let(:consumer) { double('consumer', name: 'foo') }
+      let(:provider) { double('provider', name: 'bar') }
+      let(:pact) { double('pact', consumer: consumer, provider: provider) }
+      let(:label) { 'consumer' }
+      let(:initials) { false }
+      let(:verification_status) { 'status' }
+
+      describe "#pact_verification_badge" do
+
+        before do
+          allow(Service).to receive(:pact_verification_badge).and_return('badge')
+          stub_const('PactBroker::Badges::CachedService::CACHE', {})
+        end
+
+        subject { CachedService.pact_verification_badge pact, label, initials, verification_status  }
+
+        it "returns the badge" do
+          expect(subject).to eq 'badge'
+        end
+
+        context "when the badge is not in the cache" do
+          before do
+            stub_const('PactBroker::Badges::CachedService::CACHE', {})
+          end
+
+          it "retrieves the badge from the Badges::Service" do
+            expect(Service).to receive(:pact_verification_badge)
+            subject
+          end
+        end
+
+        context "when the badge is in the cache" do
+          it "returns the cached badge" do
+            expect(Service).to receive(:pact_verification_badge).once
+            CachedService.pact_verification_badge pact, label, initials, verification_status
+            CachedService.pact_verification_badge pact, label, initials, verification_status
+          end
+        end
+      end
+    end
+  end
+end