Merge branch 'master' into milestone-ref

15 files changed, 820 insertions, 6 deletions

diff --git a/spec/lib/banzai/filter/relative_link_filter_spec.rb b/spec/lib/banzai/filter/relative_link_filter_spec.rb
index 0b3e5ecbc9f..0e6685f0ffb 100644
--- a/spec/lib/banzai/filter/relative_link_filter_spec.rb
+++ b/spec/lib/banzai/filter/relative_link_filter_spec.rb
@@ -92,6 +92,14 @@ describe Banzai::Filter::RelativeLinkFilter, lib: true do
         to eq "/#{project_path}/blob/#{ref}/doc/api/README.md"
     end
 
+    it 'rebuilds relative URL for a file in the repository root' do
+      relative_link = link('../README.md')
+      doc = filter(relative_link, requested_path: 'doc/some-file.md')
+
+      expect(doc.at_css('a')['href']).
+        to eq "/#{project_path}/blob/#{ref}/README.md"
+    end
+
     it 'rebuilds relative URL for a file in the repo with an anchor' do
       doc = filter(link('README.md#section'))
       expect(doc.at_css('a')['href']).
diff --git a/spec/lib/banzai/filter/user_reference_filter_spec.rb b/spec/lib/banzai/filter/user_reference_filter_spec.rb
index 3534bf97784..8bdebae1841 100644
--- a/spec/lib/banzai/filter/user_reference_filter_spec.rb
+++ b/spec/lib/banzai/filter/user_reference_filter_spec.rb
@@ -37,9 +37,22 @@ describe Banzai::Filter::UserReferenceFilter, lib: true do
         .to eq urls.namespace_project_url(project.namespace, project)
     end
 
-    it 'adds to the results hash' do
-      result = reference_pipeline_result("Hey #{reference}")
-      expect(result[:references][:user]).to eq [project.creator]
+    context "when the author is a member of the project" do
+
+      it 'adds to the results hash' do
+        result = reference_pipeline_result("Hey #{reference}", author: project.creator)
+        expect(result[:references][:user]).to eq [project.creator]
+      end
+    end
+
+    context "when the author is not a member of the project" do
+
+      let(:other_user) { create(:user) }
+
+      it "doesn't add to the results hash" do
+        result = reference_pipeline_result("Hey #{reference}", author: other_user)
+        expect(result[:references][:user]).to eq []
+      end
     end
   end
 
diff --git a/spec/lib/banzai/querying_spec.rb b/spec/lib/banzai/querying_spec.rb
new file mode 100644
index 00000000000..27da2a7439c
--- /dev/null
+++ b/spec/lib/banzai/querying_spec.rb
@@ -0,0 +1,13 @@
+require 'spec_helper'
+
+describe Banzai::Querying do
+  describe '.css' do
+    it 'optimizes queries for elements with classes' do
+      document = double(:document)
+
+      expect(document).to receive(:xpath).with(/^descendant::a/)
+
+      described_class.css(document, 'a.gfm')
+    end
+  end
+end
diff --git a/spec/lib/ci/gitlab_ci_yaml_processor_spec.rb b/spec/lib/ci/gitlab_ci_yaml_processor_spec.rb
index c90133fbf03..d15100fc6d8 100644
--- a/spec/lib/ci/gitlab_ci_yaml_processor_spec.rb
+++ b/spec/lib/ci/gitlab_ci_yaml_processor_spec.rb
@@ -3,7 +3,7 @@ require 'spec_helper'
 module Ci
   describe GitlabCiYamlProcessor, lib: true do
     let(:path) { 'path' }
-    
+
     describe "#builds_for_ref" do
       let(:type) { 'test' }
 
@@ -29,7 +29,7 @@ module Ci
           when: "on_success"
         })
       end
-      
+
       describe :only do
         it "does not return builds if only has another branch" do
           config = YAML.dump({
@@ -517,7 +517,7 @@ module Ci
         end.to raise_error(GitlabCiYamlProcessor::ValidationError, "Unknown parameter: extra")
       end
 
-      it "returns errors if there is no any jobs defined" do
+      it "returns errors if there are no jobs defined" do
         config = YAML.dump({ before_script: ["bundle update"] })
         expect do
           GitlabCiYamlProcessor.new(config, path)
diff --git a/spec/lib/gitlab/metrics/delta_spec.rb b/spec/lib/gitlab/metrics/delta_spec.rb
new file mode 100644
index 00000000000..718387cdee1
--- /dev/null
+++ b/spec/lib/gitlab/metrics/delta_spec.rb
@@ -0,0 +1,16 @@
+require 'spec_helper'
+
+describe Gitlab::Metrics::Delta do
+  let(:delta) { described_class.new }
+
+  describe '#compared_with' do
+    it 'returns the delta as a Numeric' do
+      expect(delta.compared_with(5)).to eq(5)
+    end
+
+    it 'bases the delta on a previously used value' do
+      expect(delta.compared_with(5)).to eq(5)
+      expect(delta.compared_with(15)).to eq(10)
+    end
+  end
+end
diff --git a/spec/lib/gitlab/metrics/instrumentation_spec.rb b/spec/lib/gitlab/metrics/instrumentation_spec.rb
new file mode 100644
index 00000000000..2a37cd40dde
--- /dev/null
+++ b/spec/lib/gitlab/metrics/instrumentation_spec.rb
@@ -0,0 +1,240 @@
+require 'spec_helper'
+
+describe Gitlab::Metrics::Instrumentation do
+  let(:transaction) { Gitlab::Metrics::Transaction.new }
+
+  before do
+    @dummy = Class.new do
+      def self.foo(text = 'foo')
+        text
+      end
+
+      def bar(text = 'bar')
+        text
+      end
+    end
+
+    allow(@dummy).to receive(:name).and_return('Dummy')
+  end
+
+  describe '.configure' do
+    it 'yields self' do
+      described_class.configure do |c|
+        expect(c).to eq(described_class)
+      end
+    end
+  end
+
+  describe '.instrument_method' do
+    describe 'with metrics enabled' do
+      before do
+        allow(Gitlab::Metrics).to receive(:enabled?).and_return(true)
+
+        described_class.instrument_method(@dummy, :foo)
+      end
+
+      it 'renames the original method' do
+        expect(@dummy).to respond_to(:_original_foo)
+      end
+
+      it 'calls the instrumented method with the correct arguments' do
+        expect(@dummy.foo).to eq('foo')
+      end
+
+      it 'tracks the call duration upon calling the method' do
+        allow(Gitlab::Metrics).to receive(:method_call_threshold).
+          and_return(0)
+
+        allow(described_class).to receive(:transaction).
+          and_return(transaction)
+
+        expect(transaction).to receive(:increment).
+          with(:method_duration, a_kind_of(Numeric))
+
+        expect(transaction).to receive(:add_metric).
+          with(described_class::SERIES, an_instance_of(Hash),
+               method: 'Dummy.foo')
+
+        @dummy.foo
+      end
+
+      it 'does not track method calls below a given duration threshold' do
+        allow(Gitlab::Metrics).to receive(:method_call_threshold).
+          and_return(100)
+
+        expect(transaction).to_not receive(:add_metric)
+
+        @dummy.foo
+      end
+    end
+
+    describe 'with metrics disabled' do
+      before do
+        allow(Gitlab::Metrics).to receive(:enabled?).and_return(false)
+      end
+
+      it 'does not instrument the method' do
+        described_class.instrument_method(@dummy, :foo)
+
+        expect(@dummy).to_not respond_to(:_original_foo)
+      end
+    end
+  end
+
+  describe '.instrument_instance_method' do
+    describe 'with metrics enabled' do
+      before do
+        allow(Gitlab::Metrics).to receive(:enabled?).and_return(true)
+
+        described_class.
+          instrument_instance_method(@dummy, :bar)
+      end
+
+      it 'renames the original method' do
+        expect(@dummy.method_defined?(:_original_bar)).to eq(true)
+      end
+
+      it 'calls the instrumented method with the correct arguments' do
+        expect(@dummy.new.bar).to eq('bar')
+      end
+
+      it 'tracks the call duration upon calling the method' do
+        allow(Gitlab::Metrics).to receive(:method_call_threshold).
+          and_return(0)
+
+        allow(described_class).to receive(:transaction).
+          and_return(transaction)
+
+        expect(transaction).to receive(:increment).
+          with(:method_duration, a_kind_of(Numeric))
+
+        expect(transaction).to receive(:add_metric).
+          with(described_class::SERIES, an_instance_of(Hash),
+               method: 'Dummy#bar')
+
+        @dummy.new.bar
+      end
+
+      it 'does not track method calls below a given duration threshold' do
+        allow(Gitlab::Metrics).to receive(:method_call_threshold).
+          and_return(100)
+
+        expect(transaction).to_not receive(:add_metric)
+
+        @dummy.new.bar
+      end
+    end
+
+    describe 'with metrics disabled' do
+      before do
+        allow(Gitlab::Metrics).to receive(:enabled?).and_return(false)
+      end
+
+      it 'does not instrument the method' do
+        described_class.
+          instrument_instance_method(@dummy, :bar)
+
+        expect(@dummy.method_defined?(:_original_bar)).to eq(false)
+      end
+    end
+  end
+
+  describe '.instrument_class_hierarchy' do
+    before do
+      allow(Gitlab::Metrics).to receive(:enabled?).and_return(true)
+
+      @child1 = Class.new(@dummy) do
+        def self.child1_foo; end
+        def child1_bar; end
+      end
+
+      @child2 = Class.new(@child1) do
+        def self.child2_foo; end
+        def child2_bar; end
+      end
+    end
+
+    it 'recursively instruments a class hierarchy' do
+      described_class.instrument_class_hierarchy(@dummy)
+
+      expect(@child1).to respond_to(:_original_child1_foo)
+      expect(@child2).to respond_to(:_original_child2_foo)
+
+      expect(@child1.method_defined?(:_original_child1_bar)).to eq(true)
+      expect(@child2.method_defined?(:_original_child2_bar)).to eq(true)
+    end
+
+    it 'does not instrument the root module' do
+      described_class.instrument_class_hierarchy(@dummy)
+
+      expect(@dummy).to_not respond_to(:_original_foo)
+      expect(@dummy.method_defined?(:_original_bar)).to eq(false)
+    end
+  end
+
+  describe '.instrument_methods' do
+    before do
+      allow(Gitlab::Metrics).to receive(:enabled?).and_return(true)
+    end
+
+    it 'instruments all public class methods' do
+      described_class.instrument_methods(@dummy)
+
+      expect(@dummy).to respond_to(:_original_foo)
+    end
+
+    it 'only instruments methods directly defined in the module' do
+      mod = Module.new do
+        def kittens
+        end
+      end
+
+      @dummy.extend(mod)
+
+      described_class.instrument_methods(@dummy)
+
+      expect(@dummy).to_not respond_to(:_original_kittens)
+    end
+
+    it 'can take a block to determine if a method should be instrumented' do
+      described_class.instrument_methods(@dummy) do
+        false
+      end
+
+      expect(@dummy).to_not respond_to(:_original_foo)
+    end
+  end
+
+  describe '.instrument_instance_methods' do
+    before do
+      allow(Gitlab::Metrics).to receive(:enabled?).and_return(true)
+    end
+
+    it 'instruments all public instance methods' do
+      described_class.instrument_instance_methods(@dummy)
+
+      expect(@dummy.method_defined?(:_original_bar)).to eq(true)
+    end
+
+    it 'only instruments methods directly defined in the module' do
+      mod = Module.new do
+        def kittens
+        end
+      end
+
+      @dummy.include(mod)
+
+      described_class.instrument_instance_methods(@dummy)
+
+      expect(@dummy.method_defined?(:_original_kittens)).to eq(false)
+    end
+
+    it 'can take a block to determine if a method should be instrumented' do
+      described_class.instrument_instance_methods(@dummy) do
+        false
+      end
+
+      expect(@dummy.method_defined?(:_original_bar)).to eq(false)
+    end
+  end
+end
diff --git a/spec/lib/gitlab/metrics/metric_spec.rb b/spec/lib/gitlab/metrics/metric_spec.rb
new file mode 100644
index 00000000000..f718d536130
--- /dev/null
+++ b/spec/lib/gitlab/metrics/metric_spec.rb
@@ -0,0 +1,51 @@
+require 'spec_helper'
+
+describe Gitlab::Metrics::Metric do
+  let(:metric) do
+    described_class.new('foo', { number: 10 }, { host: 'localtoast' })
+  end
+
+  describe '#series' do
+    subject { metric.series }
+
+    it { is_expected.to eq('foo') }
+  end
+
+  describe '#values' do
+    subject { metric.values }
+
+    it { is_expected.to eq({ number: 10 }) }
+  end
+
+  describe '#tags' do
+    subject { metric.tags }
+
+    it { is_expected.to eq({ host: 'localtoast' }) }
+  end
+
+  describe '#to_hash' do
+    it 'returns a Hash' do
+      expect(metric.to_hash).to be_an_instance_of(Hash)
+    end
+
+    describe 'the returned Hash' do
+      let(:hash) { metric.to_hash }
+
+      it 'includes the series' do
+        expect(hash[:series]).to eq('foo')
+      end
+
+      it 'includes the tags' do
+        expect(hash[:tags]).to be_an_instance_of(Hash)
+      end
+
+      it 'includes the values' do
+        expect(hash[:values]).to eq({ number: 10 })
+      end
+
+      it 'includes the timestamp' do
+        expect(hash[:timestamp]).to be_an_instance_of(Fixnum)
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/metrics/rack_middleware_spec.rb b/spec/lib/gitlab/metrics/rack_middleware_spec.rb
new file mode 100644
index 00000000000..a143fe4cfcd
--- /dev/null
+++ b/spec/lib/gitlab/metrics/rack_middleware_spec.rb
@@ -0,0 +1,63 @@
+require 'spec_helper'
+
+describe Gitlab::Metrics::RackMiddleware do
+  let(:app) { double(:app) }
+
+  let(:middleware) { described_class.new(app) }
+
+  let(:env) { { 'REQUEST_METHOD' => 'GET', 'REQUEST_URI' => '/foo' } }
+
+  describe '#call' do
+    before do
+      expect_any_instance_of(Gitlab::Metrics::Transaction).to receive(:finish)
+    end
+
+    it 'tracks a transaction' do
+      expect(app).to receive(:call).with(env).and_return('yay')
+
+      expect(middleware.call(env)).to eq('yay')
+    end
+
+    it 'tags a transaction with the name and action of a controller' do
+      klass      = double(:klass, name: 'TestController')
+      controller = double(:controller, class: klass, action_name: 'show')
+
+      env['action_controller.instance'] = controller
+
+      allow(app).to receive(:call).with(env)
+
+      expect(middleware).to receive(:tag_controller).
+        with(an_instance_of(Gitlab::Metrics::Transaction), env)
+
+      middleware.call(env)
+    end
+  end
+
+  describe '#transaction_from_env' do
+    let(:transaction) { middleware.transaction_from_env(env) }
+
+    it 'returns a Transaction' do
+      expect(transaction).to be_an_instance_of(Gitlab::Metrics::Transaction)
+    end
+
+    it 'tags the transaction with the request method and URI' do
+      expect(transaction.tags[:request_method]).to eq('GET')
+      expect(transaction.tags[:request_uri]).to eq('/foo')
+    end
+  end
+
+  describe '#tag_controller' do
+    let(:transaction) { middleware.transaction_from_env(env) }
+
+    it 'tags a transaction with the name and action of a controller' do
+      klass      = double(:klass, name: 'TestController')
+      controller = double(:controller, class: klass, action_name: 'show')
+
+      env['action_controller.instance'] = controller
+
+      middleware.tag_controller(transaction, env)
+
+      expect(transaction.tags[:action]).to eq('TestController#show')
+    end
+  end
+end
diff --git a/spec/lib/gitlab/metrics/sampler_spec.rb b/spec/lib/gitlab/metrics/sampler_spec.rb
new file mode 100644
index 00000000000..27211350fbe
--- /dev/null
+++ b/spec/lib/gitlab/metrics/sampler_spec.rb
@@ -0,0 +1,119 @@
+require 'spec_helper'
+
+describe Gitlab::Metrics::Sampler do
+  let(:sampler) { described_class.new(5) }
+
+  after do
+    Allocations.stop if Gitlab::Metrics.mri?
+  end
+
+  describe '#start' do
+    it 'gathers a sample at a given interval' do
+      expect(sampler).to receive(:sleep).with(5)
+      expect(sampler).to receive(:sample)
+      expect(sampler).to receive(:loop).and_yield
+
+      sampler.start.join
+    end
+  end
+
+  describe '#sample' do
+    it 'samples various statistics' do
+      expect(sampler).to receive(:sample_memory_usage)
+      expect(sampler).to receive(:sample_file_descriptors)
+      expect(sampler).to receive(:sample_objects)
+      expect(sampler).to receive(:sample_gc)
+      expect(sampler).to receive(:flush)
+
+      sampler.sample
+    end
+
+    it 'clears any GC profiles' do
+      expect(sampler).to receive(:flush)
+      expect(GC::Profiler).to receive(:clear)
+
+      sampler.sample
+    end
+  end
+
+  describe '#flush' do
+    it 'schedules the metrics using Sidekiq' do
+      expect(Gitlab::Metrics).to receive(:submit_metrics).
+        with([an_instance_of(Hash)])
+
+      sampler.sample_memory_usage
+      sampler.flush
+    end
+  end
+
+  describe '#sample_memory_usage' do
+    it 'adds a metric containing the memory usage' do
+      expect(Gitlab::Metrics::System).to receive(:memory_usage).
+        and_return(9000)
+
+      expect(sampler).to receive(:add_metric).
+        with(/memory_usage/, value: 9000).
+        and_call_original
+
+      sampler.sample_memory_usage
+    end
+  end
+
+  describe '#sample_file_descriptors' do
+    it 'adds a metric containing the amount of open file descriptors' do
+      expect(Gitlab::Metrics::System).to receive(:file_descriptor_count).
+        and_return(4)
+
+      expect(sampler).to receive(:add_metric).
+        with(/file_descriptors/, value: 4).
+        and_call_original
+
+      sampler.sample_file_descriptors
+    end
+  end
+
+  describe '#sample_objects' do
+    it 'adds a metric containing the amount of allocated objects' do
+      expect(sampler).to receive(:add_metric).
+        with(/object_counts/, an_instance_of(Hash), an_instance_of(Hash)).
+        at_least(:once).
+        and_call_original
+
+      sampler.sample_objects
+    end
+  end
+
+  describe '#sample_gc' do
+    it 'adds a metric containing garbage collection statistics' do
+      expect(GC::Profiler).to receive(:total_time).and_return(0.24)
+
+      expect(sampler).to receive(:add_metric).
+        with(/gc_statistics/, an_instance_of(Hash)).
+        and_call_original
+
+      sampler.sample_gc
+    end
+  end
+
+  describe '#add_metric' do
+    it 'prefixes the series name for a Rails process' do
+      expect(sampler).to receive(:sidekiq?).and_return(false)
+
+      expect(Gitlab::Metrics::Metric).to receive(:new).
+        with('rails_cats', { value: 10 }, {}).
+        and_call_original
+
+      sampler.add_metric('cats', value: 10)
+    end
+
+    it 'prefixes the series name for a Sidekiq process' do
+      expect(sampler).to receive(:sidekiq?).and_return(true)
+
+      expect(Gitlab::Metrics::Metric).to receive(:new).
+        with('sidekiq_cats', { value: 10 }, {}).
+        and_call_original
+
+      sampler.add_metric('cats', value: 10)
+    end
+  end
+end
diff --git a/spec/lib/gitlab/metrics/sidekiq_middleware_spec.rb b/spec/lib/gitlab/metrics/sidekiq_middleware_spec.rb
new file mode 100644
index 00000000000..5882e7d81c7
--- /dev/null
+++ b/spec/lib/gitlab/metrics/sidekiq_middleware_spec.rb
@@ -0,0 +1,26 @@
+require 'spec_helper'
+
+describe Gitlab::Metrics::SidekiqMiddleware do
+  let(:middleware) { described_class.new }
+
+  describe '#call' do
+    it 'tracks the transaction' do
+      worker = Class.new.new
+
+      expect_any_instance_of(Gitlab::Metrics::Transaction).to receive(:finish)
+
+      middleware.call(worker, 'test', :test) { nil }
+    end
+  end
+
+  describe '#tag_worker' do
+    it 'adds the worker class and action to the transaction' do
+      trans  = Gitlab::Metrics::Transaction.new
+      worker = double(:worker, class: double(:class, name: 'TestWorker'))
+
+      expect(trans).to receive(:add_tag).with(:action, 'TestWorker#perform')
+
+      middleware.tag_worker(trans, worker)
+    end
+  end
+end
diff --git a/spec/lib/gitlab/metrics/subscribers/action_view_spec.rb b/spec/lib/gitlab/metrics/subscribers/action_view_spec.rb
new file mode 100644
index 00000000000..05e4fbbeb51
--- /dev/null
+++ b/spec/lib/gitlab/metrics/subscribers/action_view_spec.rb
@@ -0,0 +1,40 @@
+require 'spec_helper'
+
+describe Gitlab::Metrics::Subscribers::ActionView do
+  let(:transaction) { Gitlab::Metrics::Transaction.new }
+
+  let(:subscriber) { described_class.new }
+
+  let(:event) do
+    root = Rails.root.to_s
+
+    double(:event, duration: 2.1,
+                   payload:  { identifier: "#{root}/app/views/x.html.haml" })
+  end
+
+  before do
+    allow(subscriber).to receive(:current_transaction).and_return(transaction)
+
+    allow(Gitlab::Metrics).to receive(:last_relative_application_frame).
+      and_return(['app/views/x.html.haml', 4])
+  end
+
+  describe '#render_template' do
+    it 'tracks rendering of a template' do
+      values = { duration: 2.1 }
+      tags   = {
+        view: 'app/views/x.html.haml',
+        file: 'app/views/x.html.haml',
+        line: 4
+      }
+
+      expect(transaction).to receive(:increment).
+        with(:view_duration, 2.1)
+
+      expect(transaction).to receive(:add_metric).
+        with(described_class::SERIES, values, tags)
+
+      subscriber.render_template(event)
+    end
+  end
+end
diff --git a/spec/lib/gitlab/metrics/subscribers/active_record_spec.rb b/spec/lib/gitlab/metrics/subscribers/active_record_spec.rb
new file mode 100644
index 00000000000..7bc070a4d09
--- /dev/null
+++ b/spec/lib/gitlab/metrics/subscribers/active_record_spec.rb
@@ -0,0 +1,35 @@
+require 'spec_helper'
+
+describe Gitlab::Metrics::Subscribers::ActiveRecord do
+  let(:transaction) { Gitlab::Metrics::Transaction.new }
+  let(:subscriber)  { described_class.new }
+
+  let(:event) do
+    double(:event, duration: 0.2,
+                   payload:  { sql: 'SELECT * FROM users WHERE id = 10' })
+  end
+
+  describe '#sql' do
+    describe 'without a current transaction' do
+      it 'simply returns' do
+        expect_any_instance_of(Gitlab::Metrics::Transaction).
+          to_not receive(:increment)
+
+        subscriber.sql(event)
+      end
+    end
+
+    describe 'with a current transaction' do
+      it 'increments the :sql_duration value' do
+        expect(subscriber).to receive(:current_transaction).
+          at_least(:once).
+          and_return(transaction)
+
+        expect(transaction).to receive(:increment).
+          with(:sql_duration, 0.2)
+
+        subscriber.sql(event)
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/metrics/system_spec.rb b/spec/lib/gitlab/metrics/system_spec.rb
new file mode 100644
index 00000000000..f8c1d956ca1
--- /dev/null
+++ b/spec/lib/gitlab/metrics/system_spec.rb
@@ -0,0 +1,29 @@
+require 'spec_helper'
+
+describe Gitlab::Metrics::System do
+  if File.exist?('/proc')
+    describe '.memory_usage' do
+      it "returns the process' memory usage in bytes" do
+        expect(described_class.memory_usage).to be > 0
+      end
+    end
+
+    describe '.file_descriptor_count' do
+      it 'returns the amount of open file descriptors' do
+        expect(described_class.file_descriptor_count).to be > 0
+      end
+    end
+  else
+    describe '.memory_usage' do
+      it 'returns 0.0' do
+        expect(described_class.memory_usage).to eq(0.0)
+      end
+    end
+
+    describe '.file_descriptor_count' do
+      it 'returns 0' do
+        expect(described_class.file_descriptor_count).to eq(0)
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/metrics/transaction_spec.rb b/spec/lib/gitlab/metrics/transaction_spec.rb
new file mode 100644
index 00000000000..b9b94947afa
--- /dev/null
+++ b/spec/lib/gitlab/metrics/transaction_spec.rb
@@ -0,0 +1,89 @@
+require 'spec_helper'
+
+describe Gitlab::Metrics::Transaction do
+  let(:transaction) { described_class.new }
+
+  describe '#duration' do
+    it 'returns the duration of a transaction in seconds' do
+      transaction.run { sleep(0.5) }
+
+      expect(transaction.duration).to be >= 0.5
+    end
+  end
+
+  describe '#run' do
+    it 'yields the supplied block' do
+      expect { |b| transaction.run(&b) }.to yield_control
+    end
+
+    it 'stores the transaction in the current thread' do
+      transaction.run do
+        expect(Thread.current[described_class::THREAD_KEY]).to eq(transaction)
+      end
+    end
+
+    it 'removes the transaction from the current thread upon completion' do
+      transaction.run { }
+
+      expect(Thread.current[described_class::THREAD_KEY]).to be_nil
+    end
+  end
+
+  describe '#add_metric' do
+    it 'adds a metric tagged with the transaction UUID' do
+      expect(Gitlab::Metrics::Metric).to receive(:new).
+        with('rails_foo', { number: 10 }, { transaction_id: transaction.uuid })
+
+      transaction.add_metric('foo', number: 10)
+    end
+  end
+
+  describe '#increment' do
+    it 'increments a counter' do
+      transaction.increment(:time, 1)
+      transaction.increment(:time, 2)
+
+      expect(transaction).to receive(:add_metric).
+        with('transactions', { duration: 0.0, time: 3 }, {})
+
+      transaction.track_self
+    end
+  end
+
+  describe '#add_tag' do
+    it 'adds a tag' do
+      transaction.add_tag(:foo, 'bar')
+
+      expect(transaction.tags).to eq({ foo: 'bar' })
+    end
+  end
+
+  describe '#finish' do
+    it 'tracks the transaction details and submits them to Sidekiq' do
+      expect(transaction).to receive(:track_self)
+      expect(transaction).to receive(:submit)
+
+      transaction.finish
+    end
+  end
+
+  describe '#track_self' do
+    it 'adds a metric for the transaction itself' do
+      expect(transaction).to receive(:add_metric).
+        with('transactions', { duration: transaction.duration }, {})
+
+      transaction.track_self
+    end
+  end
+
+  describe '#submit' do
+    it 'submits the metrics to Sidekiq' do
+      transaction.track_self
+
+      expect(Gitlab::Metrics).to receive(:submit_metrics).
+        with([an_instance_of(Hash)])
+
+      transaction.submit
+    end
+  end
+end
diff --git a/spec/lib/gitlab/metrics_spec.rb b/spec/lib/gitlab/metrics_spec.rb
new file mode 100644
index 00000000000..c2782f95c8e
--- /dev/null
+++ b/spec/lib/gitlab/metrics_spec.rb
@@ -0,0 +1,72 @@
+require 'spec_helper'
+
+describe Gitlab::Metrics do
+  describe '.settings' do
+    it 'returns a Hash' do
+      expect(described_class.settings).to be_an_instance_of(Hash)
+    end
+  end
+
+  describe '.enabled?' do
+    it 'returns a boolean' do
+      expect([true, false].include?(described_class.enabled?)).to eq(true)
+    end
+  end
+
+  describe '.last_relative_application_frame' do
+    it 'returns an Array containing a file path and line number' do
+      file, line = described_class.last_relative_application_frame
+
+      expect(line).to eq(__LINE__ - 2)
+      expect(file).to eq('spec/lib/gitlab/metrics_spec.rb')
+    end
+  end
+
+  describe '#submit_metrics' do
+    it 'prepares and writes the metrics to InfluxDB' do
+      connection = double(:connection)
+      pool       = double(:pool)
+
+      expect(pool).to receive(:with).and_yield(connection)
+      expect(connection).to receive(:write_points).with(an_instance_of(Array))
+      expect(Gitlab::Metrics).to receive(:pool).and_return(pool)
+
+      described_class.submit_metrics([{ 'series' => 'kittens', 'tags' => {} }])
+    end
+  end
+
+  describe '#prepare_metrics' do
+    it 'returns a Hash with the keys as Symbols' do
+      metrics = described_class.
+        prepare_metrics([{ 'values' => {}, 'tags' => {} }])
+
+      expect(metrics).to eq([{ values: {}, tags: {} }])
+    end
+
+    it 'escapes tag values' do
+      metrics = described_class.prepare_metrics([
+        { 'values' => {}, 'tags' => { 'foo' => 'bar=' } }
+      ])
+
+      expect(metrics).to eq([{ values: {}, tags: { 'foo' => 'bar\\=' } }])
+    end
+
+    it 'drops empty tags' do
+      metrics = described_class.prepare_metrics([
+        { 'values' => {}, 'tags' => { 'cats' => '', 'dogs' => nil } }
+      ])
+
+      expect(metrics).to eq([{ values: {}, tags: {} }])
+    end
+  end
+
+  describe '#escape_value' do
+    it 'escapes an equals sign' do
+      expect(described_class.escape_value('foo=')).to eq('foo\\=')
+    end
+
+    it 'casts values to Strings' do
+      expect(described_class.escape_value(10)).to eq('10')
+    end
+  end
+end