1 files changed, 94 insertions, 0 deletions
diff --git a/spec/lib/gitlab/metrics/samplers/action_cable_sampler_spec.rb b/spec/lib/gitlab/metrics/samplers/action_cable_sampler_spec.rb
new file mode 100644
index 00000000000..7f05f35c941
--- /dev/null
+++ b/spec/lib/gitlab/metrics/samplers/action_cable_sampler_spec.rb
@@ -0,0 +1,94 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Metrics::Samplers::ActionCableSampler do
+  let(:action_cable) { instance_double(ActionCable::Server::Base) }
+
+  subject { described_class.new(action_cable: action_cable) }
+
+  describe '#interval' do
+    it 'samples every five seconds by default' do
+      expect(subject.interval).to eq(5)
+    end
+
+    it 'samples at other intervals if requested' do
+      expect(described_class.new(11).interval).to eq(11)
+    end
+  end
+
+  describe '#sample' do
+    let(:pool) { instance_double(Concurrent::ThreadPoolExecutor) }
+
+    before do
+      allow(action_cable).to receive_message_chain(:worker_pool, :executor).and_return(pool)
+      allow(action_cable).to receive(:connections).and_return([])
+      allow(pool).to receive(:min_length).and_return(1)
+      allow(pool).to receive(:max_length).and_return(2)
+      allow(pool).to receive(:length).and_return(3)
+      allow(pool).to receive(:largest_length).and_return(4)
+      allow(pool).to receive(:completed_task_count).and_return(5)
+      allow(pool).to receive(:queue_length).and_return(6)
+    end
+
+    shared_examples 'collects metrics' do |expected_labels|
+      it 'includes active connections' do
+        expect(subject.metrics[:active_connections]).to receive(:set).with(expected_labels, 0)
+
+        subject.sample
+      end
+
+      it 'includes minimum worker pool size' do
+        expect(subject.metrics[:pool_min_size]).to receive(:set).with(expected_labels, 1)
+
+        subject.sample
+      end
+
+      it 'includes maximum worker pool size' do
+        expect(subject.metrics[:pool_max_size]).to receive(:set).with(expected_labels, 2)
+
+        subject.sample
+      end
+
+      it 'includes current worker pool size' do
+        expect(subject.metrics[:pool_current_size]).to receive(:set).with(expected_labels, 3)
+
+        subject.sample
+      end
+
+      it 'includes largest worker pool size' do
+        expect(subject.metrics[:pool_largest_size]).to receive(:set).with(expected_labels, 4)
+
+        subject.sample
+      end
+
+      it 'includes worker pool completed task count' do
+        expect(subject.metrics[:pool_completed_tasks]).to receive(:set).with(expected_labels, 5)
+
+        subject.sample
+      end
+
+      it 'includes worker pool pending task count' do
+        expect(subject.metrics[:pool_pending_tasks]).to receive(:set).with(expected_labels, 6)
+
+        subject.sample
+      end
+    end
+
+    context 'for in-app mode' do
+      before do
+        expect(Gitlab::ActionCable::Config).to receive(:in_app?).and_return(true)
+      end
+
+      it_behaves_like 'collects metrics', server_mode: 'in-app'
+    end
+
+    context 'for standalone mode' do
+      before do
+        expect(Gitlab::ActionCable::Config).to receive(:in_app?).and_return(false)
+      end
+
+      it_behaves_like 'collects metrics', server_mode: 'standalone'
+    end
+  end
+end