1 files changed, 52 insertions, 0 deletions
diff --git a/spec/lib/gitlab/process_memory_cache/helper_spec.rb b/spec/lib/gitlab/process_memory_cache/helper_spec.rb
new file mode 100644
index 00000000000..890642b1d5e
--- /dev/null
+++ b/spec/lib/gitlab/process_memory_cache/helper_spec.rb
@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::ProcessMemoryCache::Helper, :use_clean_rails_memory_store_caching do
+  let(:minimal_test_class) do
+    Class.new do
+      include Gitlab::ProcessMemoryCache::Helper
+
+      def cached_content
+        fetch_memory_cache(:cached_content_instance_key) { expensive_computation }
+      end
+
+      def clear_cached_content
+        invalidate_memory_cache(:cached_content_instance_key)
+      end
+    end
+  end
+
+  before do
+    stub_const("MinimalTestClass", minimal_test_class)
+  end
+
+  subject { MinimalTestClass.new }
+
+  describe '.fetch_memory_cache' do
+    it 'memoizes the result' do
+      is_expected.to receive(:expensive_computation).once.and_return(1)
+
+      2.times do
+        expect(subject.cached_content).to eq(1)
+      end
+    end
+
+    it 'resets the cache when the shared key is missing', :aggregate_failures do
+      expect(Rails.cache).to receive(:read).with(:cached_content_instance_key).twice.and_return(nil)
+      is_expected.to receive(:expensive_computation).thrice.and_return(1, 2, 3)
+
+      3.times do |index|
+        expect(subject.cached_content).to eq(index + 1)
+      end
+    end
+  end
+
+  describe '.invalidate_memory_cache' do
+    it 'invalidates the cache' do
+      is_expected.to receive(:expensive_computation).twice.and_return(1, 2)
+
+      expect { subject.clear_cached_content }.to change { subject.cached_content }
+    end
+  end
+end