Add healthcheck endpoint, spec testing

spec/integration/api/healthcheck_spec.rb

@@ -0,0 +1,56 @@
+require 'spec_helper'
+require 'rack/test'
+
+describe Vmpooler::API::Healthcheck do
+  include Rack::Test::Methods
+
+  def app()
+    Vmpooler::API
+  end
+
+  # Added to ensure no leakage in rack state from previous tests.
+  # Removes all routes, filters, middleware and extension hooks from the current class
+  # https://rubydoc.info/gems/sinatra/Sinatra/Base#reset!-class_method
+  before(:each) do
+    app.reset!
+  end
+
+  let(:config) {
+    {
+        config: {
+            'site_name' => 'test pooler',
+            'vm_lifetime_auth' => 2,
+        },
+        pools: [
+                    {'name' => 'pool1', 'size' => 5, 'alias' => ['poolone', 'poolun']},
+                    {'name' => 'pool2', 'size' => 10},
+                    {'name' => 'pool3', 'size' => 10, 'alias' => 'NotArray'}
+                ]
+    }
+  }
+
+  let(:current_time) { Time.now }
+
+  let(:metrics) {
+    double("metrics")
+  }
+
+  before(:each) do
+    expect(app).to receive(:run!).once
+    expect(metrics).to receive(:setup_prometheus_metrics)
+    expect(metrics).to receive(:prometheus_prefix)
+    expect(metrics).to receive(:prometheus_endpoint)
+    app.execute([:api], config, redis, metrics, nil)
+    app.settings.set :config, auth: false
+  end
+
+  describe '/healthcheck' do
+    it 'returns OK' do
+      get "/healthcheck"
+      expect(last_response.header['Content-Type']).to eq('application/json')
+      expect(last_response.status).to eq(200)
+      result = JSON.parse(last_response.body)
+      expect(result).to eq({'ok' => true})
+    end
+  end
+end