1 files changed, 39 insertions, 0 deletions
diff --git a/spec/lib/gitlab/metrics/exporter/metrics_middleware_spec.rb b/spec/lib/gitlab/metrics/exporter/metrics_middleware_spec.rb
new file mode 100644
index 00000000000..ac5721f5974
--- /dev/null
+++ b/spec/lib/gitlab/metrics/exporter/metrics_middleware_spec.rb
@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Metrics::Exporter::MetricsMiddleware do
+  let(:app) { double(:app) }
+  let(:pid) { 'fake_exporter' }
+  let(:env) { { 'PATH_INFO' => '/path', 'REQUEST_METHOD' => 'GET' } }
+
+  subject(:middleware) { described_class.new(app, pid) }
+
+  def metric(name, method, path, status)
+    metric = ::Prometheus::Client.registry.get(name)
+    return unless metric
+
+    values = metric.values.transform_keys { |k| k.slice(:method, :path, :pid, :code) }
+    values[{ method: method, path: path, pid: pid, code: status.to_s }]&.get
+  end
+
+  before do
+    expect(app).to receive(:call).with(env).and_return([200, {}, []])
+  end
+
+  describe '#call', :prometheus do
+    it 'records a total requests metric' do
+      response = middleware.call(env)
+
+      expect(response).to eq([200, {}, []])
+      expect(metric(:exporter_http_requests_total, 'get', '/path', 200)).to eq(1.0)
+    end
+
+    it 'records a request duration histogram' do
+      response = middleware.call(env)
+
+      expect(response).to eq([200, {}, []])
+      expect(metric(:exporter_http_request_duration_seconds, 'get', '/path', 200)).to be_a(Hash)
+    end
+  end
+end