1 files changed, 66 insertions, 0 deletions
diff --git a/spec/experiments/application_experiment/cache_spec.rb b/spec/experiments/application_experiment/cache_spec.rb
new file mode 100644
index 00000000000..a420d557155
--- /dev/null
+++ b/spec/experiments/application_experiment/cache_spec.rb
@@ -0,0 +1,66 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe ApplicationExperiment::Cache do
+  let(:key_name) { 'experiment_name' }
+  let(:field_name) { 'abc123' }
+  let(:key_field) { [key_name, field_name].join(':') }
+  let(:shared_state) { Gitlab::Redis::SharedState }
+
+  around do |example|
+    shared_state.with { |r| r.del(key_name) }
+    example.run
+    shared_state.with { |r| r.del(key_name) }
+  end
+
+  it "allows reading, writing and deleting", :aggregate_failures do
+    # we test them all together because they are largely interdependent
+
+    expect(subject.read(key_field)).to be_nil
+    expect(shared_state.with { |r| r.hget(key_name, field_name) }).to be_nil
+
+    subject.write(key_field, 'value')
+
+    expect(subject.read(key_field)).to eq('value')
+    expect(shared_state.with { |r| r.hget(key_name, field_name) }).to eq('value')
+
+    subject.delete(key_field)
+
+    expect(subject.read(key_field)).to be_nil
+    expect(shared_state.with { |r| r.hget(key_name, field_name) }).to be_nil
+  end
+
+  it "handles the fetch with a block behavior (which is read/write)" do
+    expect(subject.fetch(key_field) { 'value1' }).to eq('value1') # rubocop:disable Style/RedundantFetchBlock
+    expect(subject.fetch(key_field) { 'value2' }).to eq('value1') # rubocop:disable Style/RedundantFetchBlock
+  end
+
+  it "can clear a whole experiment cache key" do
+    subject.write(key_field, 'value')
+    subject.clear(key: key_field)
+
+    expect(shared_state.with { |r| r.get(key_name) }).to be_nil
+  end
+
+  it "doesn't allow clearing a key from the cache that's not a hash (definitely not an experiment)" do
+    shared_state.with { |r| r.set(key_name, 'value') }
+
+    expect { subject.clear(key: key_name) }.to raise_error(
+      ArgumentError,
+      'invalid call to clear a non-hash cache key'
+    )
+  end
+
+  context "when the :caching_experiments feature is disabled" do
+    before do
+      stub_feature_flags(caching_experiments: false)
+    end
+
+    it "doesn't write to the cache" do
+      subject.write(key_field, 'value')
+
+      expect(subject.read(key_field)).to be_nil
+    end
+  end
+end