Use alternate search algorithm provided by params

Co-authored-by: Carolyn Cole <carolyncole@users.noreply.github.com>
Co-authored-by: James R. Griffin III <jrgriffiniii@users.noreply.github.com>
Co-authored-by: Eliot Jordan <eliotjordan@users.noreply.github.com>

app/controllers/catalog_controller.rb

@@ -789,7 +789,13 @@ def basic_response
 
     def search_service_context
       return {} unless Flipflop.multi_algorithm?
-      return {} unless params[:search_algorithm] == "alternate"
-      { search_builder_class: AlternateSearchBuilder }
+      return {} unless alternate_search_builder_class # use default if none specified
+      { search_builder_class: alternate_search_builder_class }
+    end
+
+    def alternate_search_builder_class
+      "#{params[:search_algorithm]}_search_builder".camelize.constantize
+    rescue NameError
+      nil
     end
 end

spec/controllers/catalog_controller_spec.rb

@@ -146,6 +146,14 @@
           expect(repository).to have_received(:search).with(instance_of(AlternateSearchBuilder))
         end
       end
+
+      context "when the search_algorithm parameter is set to 'not_a_real_class'" do
+        it "uses the default search builder" do
+          get :index, params: { q: "coffee", search_algorithm: "not_a_real_class" }
+
+          expect(repository).to have_received(:search).with(instance_of(SearchBuilder))
+        end
+      end
     end
 
     context "when the multi-algorithm feature is off" do