1 files changed, 106 insertions, 0 deletions
diff --git a/spec/lib/gitlab/pagination/gitaly_keyset_pager_spec.rb b/spec/lib/gitlab/pagination/gitaly_keyset_pager_spec.rb
new file mode 100644
index 00000000000..156a440833c
--- /dev/null
+++ b/spec/lib/gitlab/pagination/gitaly_keyset_pager_spec.rb
@@ -0,0 +1,106 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Pagination::GitalyKeysetPager do
+  let(:pager) { described_class.new(request_context, project) }
+
+  let_it_be(:project) { create(:project, :repository) }
+
+  let(:request_context) { double("request context") }
+  let(:finder) { double("branch finder") }
+  let(:custom_port) { 8080 }
+  let(:incoming_api_projects_url) { "#{Gitlab.config.gitlab.url}:#{custom_port}/api/v4/projects" }
+
+  before do
+    stub_config_setting(port: custom_port)
+  end
+
+  describe '.paginate' do
+    let(:base_query) { { per_page: 2 } }
+    let(:query) { base_query }
+
+    before do
+      allow(request_context).to receive(:params).and_return(query)
+      allow(request_context).to receive(:header)
+    end
+
+    shared_examples_for 'offset pagination' do
+      let(:paginated_array) { double 'paginated array' }
+      let(:branches) { [] }
+
+      it 'uses offset pagination' do
+        expect(finder).to receive(:execute).and_return(branches)
+        expect(Kaminari).to receive(:paginate_array).with(branches).and_return(paginated_array)
+        expect_next_instance_of(Gitlab::Pagination::OffsetPagination) do |offset_pagination|
+          expect(offset_pagination).to receive(:paginate).with(paginated_array)
+        end
+
+        pager.paginate(finder)
+      end
+    end
+
+    context 'with branch_list_keyset_pagination feature off' do
+      before do
+        stub_feature_flags(branch_list_keyset_pagination: false)
+      end
+
+      context 'without keyset pagination option' do
+        it_behaves_like 'offset pagination'
+      end
+
+      context 'with keyset pagination option' do
+        let(:query) { base_query.merge(pagination: 'keyset') }
+
+        it_behaves_like 'offset pagination'
+      end
+    end
+
+    context 'with branch_list_keyset_pagination feature on' do
+      before do
+        stub_feature_flags(branch_list_keyset_pagination: project)
+      end
+
+      context 'without keyset pagination option' do
+        it_behaves_like 'offset pagination'
+      end
+
+      context 'with keyset pagination option' do
+        let(:query) { base_query.merge(pagination: 'keyset') }
+        let(:fake_request) { double(url: "#{incoming_api_projects_url}?#{query.to_query}") }
+
+        before do
+          allow(request_context).to receive(:request).and_return(fake_request)
+          expect(finder).to receive(:execute).with(gitaly_pagination: true).and_return(branches)
+        end
+
+        context 'when next page could be available' do
+          let(:branch1) { double 'branch', name: 'branch1' }
+          let(:branch2) { double 'branch', name: 'branch2' }
+          let(:branches) { [branch1, branch2] }
+
+          let(:expected_next_page_link) { %Q(<#{incoming_api_projects_url}?#{query.merge(page_token: branch2.name).to_query}>; rel="next") }
+
+          it 'uses keyset pagination and adds link headers' do
+            expect(request_context).to receive(:header).with('Links', expected_next_page_link)
+            expect(request_context).to receive(:header).with('Link', expected_next_page_link)
+
+            pager.paginate(finder)
+          end
+        end
+
+        context 'when the current page is the last page' do
+          let(:branch1) { double 'branch', name: 'branch1' }
+          let(:branches) { [branch1] }
+
+          it 'uses keyset pagination without link headers' do
+            expect(request_context).not_to receive(:header).with('Links', anything)
+            expect(request_context).not_to receive(:header).with('Link', anything)
+
+            pager.paginate(finder)
+          end
+        end
+      end
+    end
+  end
+end