Make external_url public and add test to ensure it

app/services/error_tracking/list_issues_service.rb

@@ -5,6 +5,10 @@ module ErrorTracking
     DEFAULT_ISSUE_STATUS = 'unresolved'
     DEFAULT_LIMIT = 20
 
+    def external_url
+      project_error_tracking_setting&.sentry_external_url
+    end
+
     private
 
     def fetch
@@ -15,10 +19,6 @@ module ErrorTracking
       { issues: response[:issues] }
     end
 
-    def external_url
-      project_error_tracking_setting&.sentry_external_url
-    end
-
     def issue_status
       params[:issue_status] || DEFAULT_ISSUE_STATUS
     end

spec/services/error_tracking/list_issues_service_spec.rb

@@ -45,4 +45,12 @@ describe ErrorTracking::ListIssuesService do
     include_examples 'error tracking service unauthorized user'
     include_examples 'error tracking service disabled'
   end
+
+  describe '#external_url' do
+    it 'calls the project setting sentry_external_url' do
+      expect(error_tracking_setting).to receive(:sentry_external_url)
+
+      subject.external_url
+    end
+  end
 end