1 files changed, 68 insertions, 0 deletions
diff --git a/spec/experiments/strategy/round_robin_spec.rb b/spec/experiments/strategy/round_robin_spec.rb
new file mode 100644
index 00000000000..f837a4701b2
--- /dev/null
+++ b/spec/experiments/strategy/round_robin_spec.rb
@@ -0,0 +1,68 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Strategy::RoundRobin, :clean_gitlab_redis_shared_state do
+  subject(:round_robin) { described_class.new('_key_', %i[variant1 variant2]) }
+
+  describe "execute" do
+    context "when there are 2 variants" do
+      it "proves out round robin in selection", :aggregate_failures do
+        expect(round_robin.execute).to eq :variant2
+        expect(round_robin.execute).to eq :variant1
+        expect(round_robin.execute).to eq :variant2
+      end
+    end
+
+    context "when there are more than 2 variants" do
+      subject(:round_robin) { described_class.new('_key_', %i[variant1 variant2 variant3]) }
+
+      it "proves out round robin in selection", :aggregate_failures do
+        expect(round_robin.execute).to eq :variant2
+        expect(round_robin.execute).to eq :variant3
+        expect(round_robin.execute).to eq :variant1
+
+        expect(round_robin.execute).to eq :variant2
+        expect(round_robin.execute).to eq :variant3
+        expect(round_robin.execute).to eq :variant1
+      end
+    end
+
+    context "when writing to cache fails" do
+      subject(:round_robin) { described_class.new('_key_', []) }
+
+      it "raises an error and logs" do
+        allow(Gitlab::Redis::SharedState).to receive(:with).and_raise(Strategy::RoundRobin::CacheError)
+        expect(Gitlab::AppLogger).to receive(:warn)
+
+        expect { round_robin.execute }.to raise_error(Strategy::RoundRobin::CacheError)
+      end
+    end
+  end
+
+  describe "#counter_expires_in" do
+    it 'displays the expiration time in seconds' do
+      round_robin.execute
+
+      expect(round_robin.counter_expires_in).to be_between(0, described_class::COUNTER_EXPIRE_TIME)
+    end
+  end
+
+  describe '#value' do
+    it 'get the count' do
+      expect(round_robin.counter_value).to eq(0)
+
+      round_robin.execute
+
+      expect(round_robin.counter_value).to eq(1)
+    end
+  end
+
+  describe '#reset!' do
+    it 'resets the count down to zero' do
+      3.times { round_robin.execute }
+
+      expect { round_robin.reset! }.to change { round_robin.counter_value }.from(3).to(0)
+    end
+  end
+end