CE-specific changes for designs `user_notes_count`

Notes call `#after_note_created` and `#after_note_destroyed` on their
noteable in callbacks, so the noteable can perform tasks particular to
them, like cache expiry.

This is in preparation of the EE-specific class
`DesignManagement::Design` clearing its `user_notes_count` cache when
its note are created or destroyed.

Refactoring Rspec behaviour testing of a counter caching service into a
shared example.

https://gitlab.com/gitlab-org/gitlab-ee/issues/13353

1 files changed, 54 insertions, 0 deletions

diff --git a/spec/support/shared_examples/services/count_service_shared_examples.rb b/spec/support/shared_examples/services/count_service_shared_examples.rb
new file mode 100644
index 00000000000..9bea180a778
--- /dev/null
+++ b/spec/support/shared_examples/services/count_service_shared_examples.rb
@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+# The calling spec should use `:use_clean_rails_memory_store_caching`
+# when including this shared example. E.g.:
+#
+#   describe MyCountService, :use_clean_rails_memory_store_caching do
+#     it_behaves_like 'a counter caching service'
+#   end
+shared_examples 'a counter caching service' do
+  describe '#count' do
+    it 'caches the count', :request_store do
+      subject.delete_cache
+      control_count = ActiveRecord::QueryRecorder.new { subject.count }.count
+      subject.delete_cache
+
+      expect { 2.times { subject.count } }.not_to exceed_query_limit(control_count)
+    end
+  end
+
+  describe '#refresh_cache' do
+    it 'refreshes the cache' do
+      original_count = subject.count
+      Rails.cache.write(subject.cache_key, original_count + 1, raw: subject.raw?)
+
+      subject.refresh_cache
+
+      expect(fetch_cache || 0).to eq(original_count)
+    end
+  end
+
+  describe '#delete_cache' do
+    it 'removes the cache' do
+      subject.count
+      subject.delete_cache
+
+      expect(fetch_cache).to be_nil
+    end
+  end
+
+  describe '#uncached_count' do
+    it 'does not cache the count' do
+      subject.delete_cache
+      subject.uncached_count
+
+      expect(fetch_cache).to be_nil
+    end
+  end
+
+  private
+
+  def fetch_cache
+    Rails.cache.read(subject.cache_key, raw: subject.raw?)
+  end
+end