1 files changed, 139 insertions, 0 deletions
diff --git a/spec/lib/api/helpers/caching_spec.rb b/spec/lib/api/helpers/caching_spec.rb
new file mode 100644
index 00000000000..a8cd061e123
--- /dev/null
+++ b/spec/lib/api/helpers/caching_spec.rb
@@ -0,0 +1,139 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+RSpec.describe API::Helpers::Caching do
+  subject(:instance) { Class.new.include(described_class).new }
+
+  describe "#present_cached" do
+    let_it_be(:project) { create(:project) }
+    let_it_be(:user) { create(:user) }
+
+    let(:presenter) { API::Entities::Todo }
+
+    let(:kwargs) do
+      {
+        with: presenter,
+        project: project
+      }
+    end
+
+    subject do
+      instance.present_cached(presentable, **kwargs)
+    end
+
+    before do
+      # We have to stub #body as it's a Grape method
+      # unavailable in the module by itself
+      expect(instance).to receive(:body) do |data|
+        data
+      end
+
+      allow(instance).to receive(:current_user) { user }
+    end
+
+    context "single object" do
+      let_it_be(:presentable) { create(:todo, project: project) }
+
+      it { is_expected.to be_a(Gitlab::Json::PrecompiledJson) }
+
+      it "uses the presenter" do
+        expect(presenter).to receive(:represent).with(presentable, project: project)
+
+        subject
+      end
+
+      it "is valid JSON" do
+        parsed = Gitlab::Json.parse(subject.to_s)
+
+        expect(parsed).to be_a(Hash)
+        expect(parsed["id"]).to eq(presentable.id)
+      end
+
+      it "fetches from the cache" do
+        expect(instance.cache).to receive(:fetch).with("#{presentable.cache_key}:#{user.cache_key}", expires_in: described_class::DEFAULT_EXPIRY).once
+
+        subject
+      end
+
+      context "when a cache context is supplied" do
+        before do
+          kwargs[:cache_context] = -> (todo) { todo.project.cache_key }
+        end
+
+        it "uses the context to augment the cache key" do
+          expect(instance.cache).to receive(:fetch).with("#{presentable.cache_key}:#{project.cache_key}", expires_in: described_class::DEFAULT_EXPIRY).once
+
+          subject
+        end
+      end
+
+      context "when expires_in is supplied" do
+        it "sets the expiry when accessing the cache" do
+          kwargs[:expires_in] = 7.days
+
+          expect(instance.cache).to receive(:fetch).with("#{presentable.cache_key}:#{user.cache_key}", expires_in: 7.days).once
+
+          subject
+        end
+      end
+    end
+
+    context "for a collection of objects" do
+      let_it_be(:presentable) { Array.new(5).map { create(:todo, project: project) } }
+
+      it { is_expected.to be_an(Gitlab::Json::PrecompiledJson) }
+
+      it "uses the presenter" do
+        presentable.each do |todo|
+          expect(presenter).to receive(:represent).with(todo, project: project)
+        end
+
+        subject
+      end
+
+      it "is valid JSON" do
+        parsed = Gitlab::Json.parse(subject.to_s)
+
+        expect(parsed).to be_an(Array)
+
+        presentable.each_with_index do |todo, i|
+          expect(parsed[i]["id"]).to eq(todo.id)
+        end
+      end
+
+      it "fetches from the cache" do
+        keys = presentable.map { |todo| "#{todo.cache_key}:#{user.cache_key}" }
+
+        expect(instance.cache).to receive(:fetch_multi).with(*keys, expires_in: described_class::DEFAULT_EXPIRY).once.and_call_original
+
+        subject
+      end
+
+      context "when a cache context is supplied" do
+        before do
+          kwargs[:cache_context] = -> (todo) { todo.project.cache_key }
+        end
+
+        it "uses the context to augment the cache key" do
+          keys = presentable.map { |todo| "#{todo.cache_key}:#{project.cache_key}" }
+
+          expect(instance.cache).to receive(:fetch_multi).with(*keys, expires_in: described_class::DEFAULT_EXPIRY).once.and_call_original
+
+          subject
+        end
+      end
+
+      context "expires_in is supplied" do
+        it "sets the expiry when accessing the cache" do
+          keys = presentable.map { |todo| "#{todo.cache_key}:#{user.cache_key}" }
+          kwargs[:expires_in] = 7.days
+
+          expect(instance.cache).to receive(:fetch_multi).with(*keys, expires_in: 7.days).once.and_call_original
+
+          subject
+        end
+      end
+    end
+  end
+end