1 files changed, 63 insertions, 0 deletions
diff --git a/spec/lib/gitlab/pagination/keyset/cursor_pager_spec.rb b/spec/lib/gitlab/pagination/keyset/cursor_pager_spec.rb
new file mode 100644
index 00000000000..783e728b34c
--- /dev/null
+++ b/spec/lib/gitlab/pagination/keyset/cursor_pager_spec.rb
@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Pagination::Keyset::CursorPager do
+  let(:relation) { Group.all.order(:name, :id) }
+  let(:per_page) { 3 }
+  let(:params) { { cursor: nil, per_page: per_page } }
+  let(:request_context) { double('request_context', params: params) }
+  let(:cursor_based_request_context) { Gitlab::Pagination::Keyset::CursorBasedRequestContext.new(request_context) }
+
+  before_all do
+    create_list(:group, 7)
+  end
+
+  describe '#paginate' do
+    subject(:paginated_result) { described_class.new(cursor_based_request_context).paginate(relation) }
+
+    it 'returns the limited relation' do
+      expect(paginated_result).to eq(relation.limit(per_page))
+    end
+  end
+
+  describe '#finalize' do
+    subject(:finalize) do
+      service = described_class.new(cursor_based_request_context)
+      # we need to do this because `finalize` can only be called
+      # after `paginate` is called. Otherwise the `paginator` object won't be set.
+      service.paginate(relation)
+      service.finalize
+    end
+
+    it 'passes information about next page to request' do
+      cursor_for_next_page = relation.keyset_paginate(**params).cursor_for_next_page
+
+      expect_next_instance_of(Gitlab::Pagination::Keyset::HeaderBuilder, request_context) do |builder|
+        expect(builder).to receive(:add_next_page_header).with({ cursor: cursor_for_next_page })
+      end
+
+      finalize
+    end
+
+    context 'when retrieving the last page' do
+      let(:relation) { Group.where('id > ?', Group.maximum(:id) - per_page).order(:name, :id) }
+
+      it 'does not build information about the next page' do
+        expect(Gitlab::Pagination::Keyset::HeaderBuilder).not_to receive(:new)
+
+        finalize
+      end
+    end
+
+    context 'when retrieving an empty page' do
+      let(:relation) { Group.where('id > ?', Group.maximum(:id) + 1).order(:name, :id) }
+
+      it 'does not build information about the next page' do
+        expect(Gitlab::Pagination::Keyset::HeaderBuilder).not_to receive(:new)
+
+        finalize
+      end
+    end
+  end
+end