1 files changed, 145 insertions, 0 deletions
diff --git a/spec/models/concerns/reactive_caching_spec.rb b/spec/models/concerns/reactive_caching_spec.rb
new file mode 100644
index 00000000000..a0765a264cf
--- /dev/null
+++ b/spec/models/concerns/reactive_caching_spec.rb
@@ -0,0 +1,145 @@
+require 'spec_helper'
+
+describe ReactiveCaching, caching: true do
+  include ReactiveCachingHelpers
+
+  class CacheTest
+    include ReactiveCaching
+
+    self.reactive_cache_key = ->(thing) { ["foo", thing.id] }
+
+    self.reactive_cache_lifetime = 5.minutes
+    self.reactive_cache_refresh_interval = 15.seconds
+
+    attr_reader :id
+
+    def initialize(id, &blk)
+      @id = id
+      @calculator = blk
+    end
+
+    def calculate_reactive_cache
+      @calculator.call
+    end
+
+    def result
+      with_reactive_cache do |data|
+        data / 2
+      end
+    end
+  end
+
+  let(:now) { Time.now.utc }
+
+  around(:each) do |example|
+    Timecop.freeze(now) { example.run }
+  end
+
+  let(:calculation) { -> { 2 + 2 } }
+  let(:cache_key) { "foo:666" }
+  let(:instance) { CacheTest.new(666, &calculation) }
+
+  describe '#with_reactive_cache' do
+    before { stub_reactive_cache }
+    subject(:go!) { instance.result }
+
+    context 'when cache is empty' do
+      it { is_expected.to be_nil }
+
+      it 'queues a background worker' do
+        expect(ReactiveCachingWorker).to receive(:perform_async).with(CacheTest, 666)
+
+        go!
+      end
+
+      it 'updates the cache lifespan' do
+        go!
+
+        expect(reactive_cache_alive?(instance)).to be_truthy
+      end
+    end
+
+    context 'when the cache is full' do
+      before { stub_reactive_cache(instance, 4) }
+
+      it { is_expected.to eq(2) }
+
+      context 'and expired' do
+        before { invalidate_reactive_cache(instance) }
+        it { is_expected.to be_nil }
+      end
+    end
+  end
+
+  describe '#clear_reactive_cache!' do
+    before do
+      stub_reactive_cache(instance, 4)
+      instance.clear_reactive_cache!
+    end
+
+    it { expect(instance.result).to be_nil }
+  end
+
+  describe '#exclusively_update_reactive_cache!' do
+    subject(:go!) { instance.exclusively_update_reactive_cache! }
+
+    context 'when the lease is free and lifetime is not exceeded' do
+      before { stub_reactive_cache(instance, "preexisting") }
+
+      it 'takes and releases the lease' do
+        expect_any_instance_of(Gitlab::ExclusiveLease).to receive(:try_obtain).and_return("000000")
+        expect(Gitlab::ExclusiveLease).to receive(:cancel).with(cache_key, "000000")
+
+        go!
+      end
+
+      it 'caches the result of #calculate_reactive_cache' do
+        go!
+
+        expect(read_reactive_cache(instance)).to eq(calculation.call)
+      end
+
+      it "enqueues a repeat worker" do
+        expect_reactive_cache_update_queued(instance)
+
+        go!
+      end
+
+      context 'and #calculate_reactive_cache raises an exception' do
+        before { stub_reactive_cache(instance, "preexisting") }
+        let(:calculation) { -> { raise "foo"} }
+
+        it 'leaves the cache untouched' do
+          expect { go! }.to raise_error("foo")
+          expect(read_reactive_cache(instance)).to eq("preexisting")
+        end
+
+        it 'enqueues a repeat worker' do
+          expect_reactive_cache_update_queued(instance)
+
+          expect { go! }.to raise_error("foo")
+        end
+      end
+    end
+
+    context 'when lifetime is exceeded' do
+      it 'skips the calculation' do
+        expect(instance).to receive(:calculate_reactive_cache).never
+
+        go!
+      end
+    end
+
+    context 'when the lease is already taken' do
+      before do
+        expect_any_instance_of(Gitlab::ExclusiveLease).to receive(:try_obtain).and_return(nil)
+      end
+
+      it 'skips the calculation' do
+        expect(instance).to receive(:calculate_reactive_cache).never
+
+        go!
+      end
+    end
+  end
+end