Add regression spec

https://gitlab.com/gitlab-org/gitlab/issues/37919

spec/requests/api/projects_spec.rb

@@ -155,6 +155,35 @@ describe API::Projects do
       project4
     end
 
+    # This is a regression spec for https://gitlab.com/gitlab-org/gitlab/issues/37919
+    context 'batch counting forks and open issues and refreshing count caches' do
+      # We expect to count these projects (only the ones on the first page, not all matching ones)
+      let(:projects) { Project.public_to_user(nil).order(id: :desc).first(per_page) }
+      let(:per_page) { 2 }
+      let(:count_service) { double }
+
+      before do
+        # Create more projects, so we have more than one page
+        create_list(:project, 5, :public)
+      end
+
+      it 'batch counts project forks' do
+        expect(::Projects::BatchForksCountService).to receive(:new).with(projects).and_return(count_service)
+        expect(count_service).to receive(:refresh_cache)
+
+        get api("/projects?per_page=#{per_page}")
+        expect(response.status).to eq 200
+      end
+
+      it 'batch counts open issues' do
+        expect(::Projects::BatchOpenIssuesCountService).to receive(:new).with(projects).and_return(count_service)
+        expect(count_service).to receive(:refresh_cache)
+
+        get api("/projects?per_page=#{per_page}")
+        expect(response.status).to eq 200
+      end
+    end
+
     context 'when unauthenticated' do
       it_behaves_like 'projects response' do
         let(:filter) { { search: project.name } }