1 files changed, 57 insertions, 0 deletions
diff --git a/spec/lib/gitlab/updated_notes_paginator_spec.rb b/spec/lib/gitlab/updated_notes_paginator_spec.rb
new file mode 100644
index 00000000000..eedc11777d4
--- /dev/null
+++ b/spec/lib/gitlab/updated_notes_paginator_spec.rb
@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::UpdatedNotesPaginator do
+  let(:issue) { create(:issue) }
+
+  let(:project) { issue.project }
+  let(:finder) { NotesFinder.new(user, target: issue, last_fetched_at: last_fetched_at) }
+  let(:user) { issue.author }
+
+  let!(:page_1) { create_list(:note, 2, noteable: issue, project: project, updated_at: 2.days.ago) }
+  let!(:page_2) { [create(:note, noteable: issue, project: project, updated_at: 1.day.ago)] }
+
+  let(:page_1_boundary) { page_1.last.updated_at + NotesFinder::FETCH_OVERLAP }
+
+  around do |example|
+    Timecop.freeze do
+      example.run
+    end
+  end
+
+  before do
+    stub_const("Gitlab::UpdatedNotesPaginator::LIMIT", 2)
+  end
+
+  subject(:paginator) { described_class.new(finder.execute, last_fetched_at: last_fetched_at) }
+
+  describe 'last_fetched_at: start of time' do
+    let(:last_fetched_at) { Time.at(0) }
+
+    it 'calculates the first page of notes', :aggregate_failures do
+      expect(paginator.notes).to match_array(page_1)
+      expect(paginator.metadata).to match(
+        more: true,
+        last_fetched_at: microseconds(page_1_boundary)
+      )
+    end
+  end
+
+  describe 'last_fetched_at: start of final page' do
+    let(:last_fetched_at) { page_1_boundary }
+
+    it 'calculates a final page', :aggregate_failures do
+      expect(paginator.notes).to match_array(page_2)
+      expect(paginator.metadata).to match(
+        more: false,
+        last_fetched_at: microseconds(Time.zone.now)
+      )
+    end
+  end
+
+  # Convert a time to an integer number of microseconds
+  def microseconds(time)
+    (time.to_i * 1_000_000) + time.usec
+  end
+end