Add tests for Geo::GeoBackfillWorker

spec/workers/geo_backfill_worker_spec.rb

 require 'spec_helper'
 
 describe Geo::GeoBackfillWorker, services: true do
+  let!(:primary)   { create(:geo_node, :primary, host: 'primary-geo-node') }
+  let!(:secondary) { create(:geo_node, :current) }
+  let!(:projects)  { create_list(:empty_project, 2) }
+
+  subject { described_class.new }
+
   describe '#perform' do
-    pending { raise 'must be implemented' }
+    it 'performs GeoSingleRepositoryBackfillWorker for each project' do
+      expect(GeoSingleRepositoryBackfillWorker).to receive(:new).exactly(2).and_call_original
+
+      subject.perform
+    end
+
+    it 'does not perform GeoSingleRepositoryBackfillWorker when node is disabled' do
+      allow(secondary).to receive(:enabled?) { false }
+
+      expect(GeoSingleRepositoryBackfillWorker).not_to receive(:new)
+
+      subject.perform
+    end
+
+    it 'does not perform GeoSingleRepositoryBackfillWorker for projects that repository exists' do
+      create_list(:project, 2)
+
+      expect(GeoSingleRepositoryBackfillWorker).to receive(:new).exactly(2).and_call_original
+
+      subject.perform
+    end
+
+    it 'does not perform GeoSingleRepositoryBackfillWorker when can not obtain a lease' do
+      allow_any_instance_of(Gitlab::ExclusiveLease).to receive(:try_obtain) { false }
+
+      expect(GeoSingleRepositoryBackfillWorker).not_to receive(:new)
+
+      subject.perform
+    end
   end
 end