Move Prometheus presentation logic to PrometheusText

+ Use NullMetrics to mock metrics when unused
+ Use method_missing in NullMetrics mocking
+ Update prometheus gem to version that correctly uses transitive dependencies
+ Ensure correct folders are used in Multiprocess prometheus client tests.
+ rename Sessions controller's metric

3 files changed, 24 insertions, 13 deletions

diff --git a/spec/controllers/metrics_controller_spec.rb b/spec/controllers/metrics_controller_spec.rb
index cd31f750ffd..7baf7d1bef9 100644
--- a/spec/controllers/metrics_controller_spec.rb
+++ b/spec/controllers/metrics_controller_spec.rb
@@ -6,10 +6,10 @@ describe MetricsController do
   let(:token) { current_application_settings.health_check_access_token }
   let(:json_response) { JSON.parse(response.body) }
 
-  around do |examples|
+  around do |example|
     Dir.mktmpdir do |tmp_dir|
       @metrics_multiproc_dir = tmp_dir
-      examples.run
+      example.run
     end
   end
 
diff --git a/spec/lib/gitlab/metrics_spec.rb b/spec/lib/gitlab/metrics_spec.rb
index 863868e1576..87c9f4ebda4 100644
--- a/spec/lib/gitlab/metrics_spec.rb
+++ b/spec/lib/gitlab/metrics_spec.rb
@@ -1,6 +1,8 @@
 require 'spec_helper'
 
 describe Gitlab::Metrics do
+  include StubENV
+
   describe '.settings' do
     it 'returns a Hash' do
       expect(described_class.settings).to be_an_instance_of(Hash)
@@ -247,45 +249,53 @@ describe Gitlab::Metrics do
 
     it_behaves_like 'prometheus metrics API'
 
-    describe '#dummy_metric' do
+    describe '#null_metric' do
       subject { described_class.provide_metric(:test) }
 
-      it { is_expected.to be_a(Gitlab::Metrics::DummyMetric) }
+      it { is_expected.to be_a(Gitlab::Metrics::NullMetric) }
     end
 
     describe '#counter' do
       subject { described_class.counter(:counter, 'doc') }
 
-      it { is_expected.to be_a(Gitlab::Metrics::DummyMetric) }
+      it { is_expected.to be_a(Gitlab::Metrics::NullMetric) }
     end
 
     describe '#summary' do
       subject { described_class.summary(:summary, 'doc') }
 
-      it { is_expected.to be_a(Gitlab::Metrics::DummyMetric) }
+      it { is_expected.to be_a(Gitlab::Metrics::NullMetric) }
     end
 
     describe '#gauge' do
       subject { described_class.gauge(:gauge, 'doc') }
 
-      it { is_expected.to be_a(Gitlab::Metrics::DummyMetric) }
+      it { is_expected.to be_a(Gitlab::Metrics::NullMetric) }
     end
 
     describe '#histogram' do
       subject { described_class.histogram(:histogram, 'doc') }
 
-      it { is_expected.to be_a(Gitlab::Metrics::DummyMetric) }
+      it { is_expected.to be_a(Gitlab::Metrics::NullMetric) }
     end
   end
 
   context 'prometheus metrics enabled' do
+    around do |example|
+      Dir.mktmpdir do |tmp_dir|
+        @metrics_multiproc_dir = tmp_dir
+        example.run
+      end
+    end
+
     before do
+      stub_const('Prometheus::Client::Multiprocdir', @metrics_multiproc_dir)
       allow(described_class).to receive(:prometheus_metrics_enabled?).and_return(true)
     end
 
     it_behaves_like 'prometheus metrics API'
 
-    describe '#dummy_metric' do
+    describe '#null_metric' do
       subject { described_class.provide_metric(:test) }
 
       it { is_expected.to be_nil }
@@ -294,25 +304,25 @@ describe Gitlab::Metrics do
     describe '#counter' do
       subject { described_class.counter(:name, 'doc') }
 
-      it { is_expected.not_to be_a(Gitlab::Metrics::DummyMetric) }
+      it { is_expected.not_to be_a(Gitlab::Metrics::NullMetric) }
     end
 
     describe '#summary' do
       subject { described_class.summary(:name, 'doc') }
 
-      it { is_expected.not_to be_a(Gitlab::Metrics::DummyMetric) }
+      it { is_expected.not_to be_a(Gitlab::Metrics::NullMetric) }
     end
 
     describe '#gauge' do
       subject { described_class.gauge(:name, 'doc') }
 
-      it { is_expected.not_to be_a(Gitlab::Metrics::DummyMetric) }
+      it { is_expected.not_to be_a(Gitlab::Metrics::NullMetric) }
     end
 
     describe '#histogram' do
       subject { described_class.histogram(:name, 'doc') }
 
-      it { is_expected.not_to be_a(Gitlab::Metrics::DummyMetric) }
+      it { is_expected.not_to be_a(Gitlab::Metrics::NullMetric) }
     end
   end
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 994c7dcbb46..f800c5bcb07 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -3,6 +3,7 @@ SimpleCovEnv.start!
 
 ENV["RAILS_ENV"] ||= 'test'
 ENV["IN_MEMORY_APPLICATION_SETTINGS"] = 'true'
+# ENV['prometheus_multiproc_dir'] = 'tmp/prometheus_multiproc_dir_test'
 
 require File.expand_path("../../config/environment", __FILE__)
 require 'rspec/rails'