Fix tests

lib/gitlab/metrics/influx_db.rb

 module Gitlab
   module Metrics
     module InfluxDb
-      include Gitlab::Metrics::Concern
+      include Gitlab::Metrics::Concern::ClassMethods
       include Gitlab::CurrentSettings
       extend self
 
@@ -106,7 +106,7 @@ module Gitlab
         real_time = (real_stop - real_start)
         cpu_time = cpu_stop - cpu_start
 
-        real_duration_seconds = self.class.fetch_histogram("gitlab_#{name}_real_duration_seconds".to_sym) do
+        real_duration_seconds = fetch_histogram("gitlab_#{name}_real_duration_seconds".to_sym) do
           docstring "Measure #{name}"
           base_labels Transaction::BASE_LABELS
           buckets EXECUTION_MEASUREMENT_BUCKETS
@@ -114,7 +114,7 @@ module Gitlab
 
         real_duration_seconds.observe(trans.labels, real_time)
 
-        cpu_duration_seconds = self.class.fetch_histogram("gitlab_#{name}_cpu_duration_seconds".to_sym) do
+        cpu_duration_seconds = fetch_histogram("gitlab_#{name}_cpu_duration_seconds".to_sym) do
           docstring "Measure #{name}"
           base_labels Transaction::BASE_LABELS
           buckets EXECUTION_MEASUREMENT_BUCKETS

spec/lib/gitlab/metrics/subscribers/action_view_spec.rb

@@ -32,7 +32,7 @@ describe Gitlab::Metrics::Subscribers::ActionView do
     end
 
     it 'observes view rendering time' do
-      expect(subscriber.send(:metric_view_rendering_duration_seconds))
+      expect(described_class.gitlab_view_rendering_duration_seconds)
         .to receive(:observe)
               .with({ view: 'app/views/x.html.haml' }, 2.1)