Add specs for http_request_duration_seconds

lib/gitlab/metrics/requests_rack_middleware.rb

@@ -3,7 +3,7 @@
 module Gitlab
   module Metrics
     class RequestsRackMiddleware
-      METHODS = %w(delete get head options patch post put trace).freeze
+      HTTP_METHODS = %w(delete get head options patch post put trace).freeze
       STATUSES = %w(200 301 304 400 401 403 404 500).freeze
 
       def initialize(app)
@@ -24,9 +24,9 @@ module Gitlab
       end
 
       def self.initialize_http_request_duration_seconds
-        METHODS.each do |method|
+        HTTP_METHODS.each do |method|
           STATUSES.each do |status|
-            ::Gitlab::Metrics.histogram(:http_request_duration_seconds, 'Request handling execution time').get({ method: method, status: status })
+            http_request_duration_seconds.get({ method: method, status: status })
           end
         end
       end

spec/lib/gitlab/metrics/requests_rack_middleware_spec.rb

@@ -63,5 +63,19 @@ describe Gitlab::Metrics::RequestsRackMiddleware do
         expect { subject.call(env) }.to raise_error(StandardError)
       end
     end
+
+    describe '.initialize_http_request_duration_seconds' do
+      it "sets labels" do
+        expected_labels = []
+        described_class::HTTP_METHODS.each do |method|
+          described_class::STATUSES.each do |status|
+            expected_labels << { method: method, status: status }
+          end
+        end
+
+        described_class.initialize_http_request_duration_seconds
+        expect(described_class.http_request_duration_seconds.values.keys).to include(*expected_labels)
+      end
+    end
   end
 end