Merge branch '21170-cycle-analytics' into 'master'

Cycle Analytics: first iteration

## What does this MR do?

- Implement the first iteration of the "Cycle Analytics" feature.

## What are the relevant issue numbers?

- Closes #21170 

## Screenshots

![cycle_analytics_screencast.gif](/uploads/d23c3c912caa6935fd47b53ca3a56b97/cycle_analytics.gif)

## Backend Tasks

- [x]  Implementation
    - [x]  Phases
        - [x]  Issue (Tracker)
        - [x]  Plan (Board)
        - [x]  Code (IDE)
        - [x]  Test (CI)
        - [x]  Review (MR)
        - [x]  Staging (CD)
        - [x]  Production (Total)
    - [x]  Make heuristics more modular
    - [x]  Scope to project
    - [x]  Date range (30 days, 90 days)
    - [x]  Access restriction
- [x]  Test
    - [x]  Find a better way to test these phases
    - [x]  Phases
        - [x]  Issue (Tracker)
        - [x]  Plan (Board)
        - [x]  Code (IDE)
        - [x]  Test (CI)
        - [x]  Review (MR)
        - [x]  Staging (CD)
        - [x]  Production (Total)
    - [x]  Test for "end case happens before start case"
    - [x]  Consolidate helper
- [x]  Miniboss review
- [x]  Performance testing with mock data
- [x]  Improve performance
    - [x]  Pre-calculate "merge requests closing issues
    - [x]  Pre-calculate everything else
- [x]  Test performance against 10k issues
- [x]  Test all pre-calculation code
    - [x]  Ci::Pipeline -> build start/finish
    - [x]  Ci::Pipeline#merge_requests
    - [x]  Issue -> record default metrics after save
    - [x]  MergeRequest -> record default metrics after save
    - [x]  Deployment -> Update "first_deployed_to_production_at" for MR metrics
    - [x]  Git Push -> Update "first commit mention" for issue metrics
    - [x]  Merge request create/update/refresh -> Update "merge requests closing issues"
- [x]  Remove `MergeRequestsClosingIssues` when necessary
- [x]  Changes to unblock Fatih
    - [x]  Add summary data
    - [x]  `stats` should be array
    - [x]  Let `stats` be `null` if all `stats` are null
- [x]  Indexes for "merge requests closing issues"
- [x]  Test summary data
- [x]  Scope everything to project
    - [x]  Find out why tests were passing
- [x]  Filter should include issues/MRs which have made it to production within the range
- [x]  Don't create duplicate `MergeRequestsClosingIssues`
- [x]  Fix tests
- [x]  MySQL median
- [x]  Assign to Douwe for review
- [x]  Fix conflicts
- [x]  Implement suggestions from Yorick's review
    - [x]  Test on PG
    - [x]  Test on MySQL
- [x]  Refactor
    - [x]  Cleanup
        - [x]  What happens if we have no data at all?
        - [x]  Extract common queries to methods / scopes
    - [x]  Remove unused queries
    - [x]  Downtime for foreign key migrations
    - [x]  Find a way around "if issue.metrics.present?" all over the place
    - [x]  Find a way around "if merge_request.metrics.present?" all over the place
    - [x]  Test migrations on a fresh database
        - [x]  MySQL
        - [x]  Pg
- [x]  Access issues
    - While the project is public and the visibility is set to "Everyone with access", you cannot visit the cycle analytics page when signed out.
- [x]  CHANGELOG
- [x]  Implement suggestions from Douwe's review
    - [x]  First set of comments
    - [x]  Second set of comments
    - [x]  Third set of comments
    - [x]  Fourth set of comments
- [x]  Make sure build is green
- [ ]  Make issue for "polish"
- [ ]  EE MR


See merge request !5986

11 files changed, 572 insertions, 0 deletions

diff --git a/spec/models/ci/pipeline_spec.rb b/spec/models/ci/pipeline_spec.rb
index f1857f846dc..550a890797e 100644
--- a/spec/models/ci/pipeline_spec.rb
+++ b/spec/models/ci/pipeline_spec.rb
@@ -187,6 +187,37 @@ describe Ci::Pipeline, models: true do
       end
     end
 
+    describe "merge request metrics" do
+      let(:project) { FactoryGirl.create :project }
+      let(:pipeline) { FactoryGirl.create(:ci_empty_pipeline, status: 'created', project: project, ref: 'master', sha: project.repository.commit('master').id) }
+      let!(:merge_request) { create(:merge_request, source_project: project, source_branch: pipeline.ref) }
+
+      context 'when transitioning to running' do
+        it 'records the build start time' do
+          time = Time.now
+          Timecop.freeze(time) { build.run }
+
+          expect(merge_request.reload.metrics.latest_build_started_at).to be_within(1.second).of(time)
+        end
+
+        it 'clears the build end time' do
+          build.run
+
+          expect(merge_request.reload.metrics.latest_build_finished_at).to be_nil
+        end
+      end
+
+      context 'when transitioning to success' do
+        it 'records the build end time' do
+          build.run
+          time = Time.now
+          Timecop.freeze(time) { build.success }
+
+          expect(merge_request.reload.metrics.latest_build_finished_at).to be_within(1.second).of(time)
+        end
+      end
+    end
+
     def create_build(name, queued_at = current, started_from = 0)
       create(:ci_build,
              name: name,
@@ -468,4 +499,28 @@ describe Ci::Pipeline, models: true do
              stage_idx: stage_idx)
     end
   end
+
+  describe "#merge_requests" do
+    let(:project) { FactoryGirl.create :project }
+    let(:pipeline) { FactoryGirl.create(:ci_empty_pipeline, status: 'created', project: project, ref: 'master', sha: project.repository.commit('master').id) }
+
+    it "returns merge requests whose `diff_head_sha` matches the pipeline's SHA" do
+      merge_request = create(:merge_request, source_project: project, source_branch: pipeline.ref)
+
+      expect(pipeline.merge_requests).to eq([merge_request])
+    end
+
+    it "doesn't return merge requests whose source branch doesn't match the pipeline's ref" do
+      create(:merge_request, source_project: project, source_branch: 'feature', target_branch: 'master')
+
+      expect(pipeline.merge_requests).to be_empty
+    end
+
+    it "doesn't return merge requests whose `diff_head_sha` doesn't match the pipeline's SHA" do
+      create(:merge_request, source_project: project, source_branch: pipeline.ref)
+      allow_any_instance_of(MergeRequest).to receive(:diff_head_sha) { '97de212e80737a608d939f648d959671fb0a0142b' }
+
+      expect(pipeline.merge_requests).to be_empty
+    end
+  end
 end
diff --git a/spec/models/cycle_analytics/code_spec.rb b/spec/models/cycle_analytics/code_spec.rb
new file mode 100644
index 00000000000..b9381e33914
--- /dev/null
+++ b/spec/models/cycle_analytics/code_spec.rb
@@ -0,0 +1,42 @@
+require 'spec_helper'
+
+describe 'CycleAnalytics#code', feature: true do
+  extend CycleAnalyticsHelpers::TestGeneration
+
+  let(:project) { create(:project) }
+  let(:from_date) { 10.days.ago }
+  let(:user) { create(:user, :admin) }
+  subject { CycleAnalytics.new(project, from: from_date) }
+
+  generate_cycle_analytics_spec(
+    phase: :code,
+    data_fn: -> (context) { { issue: context.create(:issue, project: context.project) } },
+    start_time_conditions: [["issue mentioned in a commit",
+                             -> (context, data) do
+                               context.create_commit_referencing_issue(data[:issue])
+                             end]],
+    end_time_conditions:   [["merge request that closes issue is created",
+                             -> (context, data) do
+                               context.create_merge_request_closing_issue(data[:issue])
+                             end]],
+    post_fn: -> (context, data) do
+      context.merge_merge_requests_closing_issue(data[:issue])
+      context.deploy_master
+    end)
+
+  context "when a regular merge request (that doesn't close the issue) is created" do
+    it "returns nil" do
+      5.times do
+        issue = create(:issue, project: project)
+
+        create_commit_referencing_issue(issue)
+        create_merge_request_closing_issue(issue, message: "Closes nothing")
+
+        merge_merge_requests_closing_issue(issue)
+        deploy_master
+      end
+
+      expect(subject.code).to be_nil
+    end
+  end
+end
diff --git a/spec/models/cycle_analytics/issue_spec.rb b/spec/models/cycle_analytics/issue_spec.rb
new file mode 100644
index 00000000000..e9cc71254ab
--- /dev/null
+++ b/spec/models/cycle_analytics/issue_spec.rb
@@ -0,0 +1,50 @@
+require 'spec_helper'
+
+describe 'CycleAnalytics#issue', models: true do
+  extend CycleAnalyticsHelpers::TestGeneration
+
+  let(:project) { create(:project) }
+  let(:from_date) { 10.days.ago }
+  let(:user) { create(:user, :admin) }
+  subject { CycleAnalytics.new(project, from: from_date) }
+
+  generate_cycle_analytics_spec(
+    phase: :issue,
+    data_fn: -> (context) { { issue: context.build(:issue, project: context.project) } },
+    start_time_conditions: [["issue created", -> (context, data) { data[:issue].save }]],
+    end_time_conditions:   [["issue associated with a milestone",
+                             -> (context, data) do
+                               if data[:issue].persisted?
+                                 data[:issue].update(milestone: context.create(:milestone, project: context.project))
+                               end
+                             end],
+                            ["list label added to issue",
+                             -> (context, data) do
+                               if data[:issue].persisted?
+                                 data[:issue].update(label_ids: [context.create(:label, lists: [context.create(:list)]).id])
+                               end
+                             end]],
+    post_fn: -> (context, data) do
+      if data[:issue].persisted?
+        context.create_merge_request_closing_issue(data[:issue].reload)
+        context.merge_merge_requests_closing_issue(data[:issue])
+        context.deploy_master
+      end
+    end)
+
+  context "when a regular label (instead of a list label) is added to the issue" do
+    it "returns nil" do
+      5.times do
+        regular_label = create(:label)
+        issue = create(:issue, project: project)
+        issue.update(label_ids: [regular_label.id])
+
+        create_merge_request_closing_issue(issue)
+        merge_merge_requests_closing_issue(issue)
+        deploy_master
+      end
+
+      expect(subject.issue).to be_nil
+    end
+  end
+end
diff --git a/spec/models/cycle_analytics/plan_spec.rb b/spec/models/cycle_analytics/plan_spec.rb
new file mode 100644
index 00000000000..5b8c96dc992
--- /dev/null
+++ b/spec/models/cycle_analytics/plan_spec.rb
@@ -0,0 +1,52 @@
+require 'spec_helper'
+
+describe 'CycleAnalytics#plan', feature: true do
+  extend CycleAnalyticsHelpers::TestGeneration
+
+  let(:project) { create(:project) }
+  let(:from_date) { 10.days.ago }
+  let(:user) { create(:user, :admin) }
+  subject { CycleAnalytics.new(project, from: from_date) }
+
+  generate_cycle_analytics_spec(
+    phase: :plan,
+    data_fn: -> (context) do
+      {
+        issue: context.create(:issue, project: context.project),
+        branch_name: context.random_git_name
+      }
+    end,
+    start_time_conditions: [["issue associated with a milestone",
+                             -> (context, data) do
+                               data[:issue].update(milestone: context.create(:milestone, project: context.project))
+                             end],
+                            ["list label added to issue",
+                             -> (context, data) do
+                               data[:issue].update(label_ids: [context.create(:label, lists: [context.create(:list)]).id])
+                             end]],
+    end_time_conditions:   [["issue mentioned in a commit",
+                             -> (context, data) do
+                               context.create_commit_referencing_issue(data[:issue], branch_name: data[:branch_name])
+                             end]],
+    post_fn: -> (context, data) do
+      context.create_merge_request_closing_issue(data[:issue], source_branch: data[:branch_name])
+      context.merge_merge_requests_closing_issue(data[:issue])
+      context.deploy_master
+    end)
+
+  context "when a regular label (instead of a list label) is added to the issue" do
+    it "returns nil" do
+      branch_name = random_git_name
+      label = create(:label)
+      issue = create(:issue, project: project)
+      issue.update(label_ids: [label.id])
+      create_commit_referencing_issue(issue, branch_name: branch_name)
+
+      create_merge_request_closing_issue(issue, source_branch: branch_name)
+      merge_merge_requests_closing_issue(issue)
+      deploy_master
+
+      expect(subject.issue).to be_nil
+    end
+  end
+end
diff --git a/spec/models/cycle_analytics/production_spec.rb b/spec/models/cycle_analytics/production_spec.rb
new file mode 100644
index 00000000000..1f5e5cab92d
--- /dev/null
+++ b/spec/models/cycle_analytics/production_spec.rb
@@ -0,0 +1,54 @@
+require 'spec_helper'
+
+describe 'CycleAnalytics#production', feature: true do
+  extend CycleAnalyticsHelpers::TestGeneration
+
+  let(:project) { create(:project) }
+  let(:from_date) { 10.days.ago }
+  let(:user) { create(:user, :admin) }
+  subject { CycleAnalytics.new(project, from: from_date) }
+
+  generate_cycle_analytics_spec(
+    phase: :production,
+    data_fn: -> (context) { { issue: context.build(:issue, project: context.project) } },
+    start_time_conditions: [["issue is created", -> (context, data) { data[:issue].save }]],
+    before_end_fn: lambda do |context, data|
+      context.create_merge_request_closing_issue(data[:issue])
+      context.merge_merge_requests_closing_issue(data[:issue])
+    end,
+    end_time_conditions:
+      [["merge request that closes issue is deployed to production", -> (context, data) { context.deploy_master }],
+       ["production deploy happens after merge request is merged (along with other changes)",
+        lambda do |context, data|
+          # Make other changes on master
+          sha = context.project.repository.commit_file(context.user, context.random_git_name, "content", "commit message", 'master', false)
+          context.project.repository.commit(sha)
+
+          context.deploy_master
+        end]])
+
+  context "when a regular merge request (that doesn't close the issue) is merged and deployed" do
+    it "returns nil" do
+      5.times do
+        merge_request = create(:merge_request)
+        MergeRequests::MergeService.new(project, user).execute(merge_request)
+        deploy_master
+      end
+
+      expect(subject.production).to be_nil
+    end
+  end
+
+  context "when the deployment happens to a non-production environment" do
+    it "returns nil" do
+      5.times do
+        issue = create(:issue, project: project)
+        merge_request = create_merge_request_closing_issue(issue)
+        MergeRequests::MergeService.new(project, user).execute(merge_request)
+        deploy_master(environment: 'staging')
+      end
+
+      expect(subject.production).to be_nil
+    end
+  end
+end
diff --git a/spec/models/cycle_analytics/review_spec.rb b/spec/models/cycle_analytics/review_spec.rb
new file mode 100644
index 00000000000..b6e26d8f261
--- /dev/null
+++ b/spec/models/cycle_analytics/review_spec.rb
@@ -0,0 +1,35 @@
+require 'spec_helper'
+
+describe 'CycleAnalytics#review', feature: true do
+  extend CycleAnalyticsHelpers::TestGeneration
+
+  let(:project) { create(:project) }
+  let(:from_date) { 10.days.ago }
+  let(:user) { create(:user, :admin) }
+  subject { CycleAnalytics.new(project, from: from_date) }
+
+  generate_cycle_analytics_spec(
+    phase: :review,
+    data_fn: -> (context) { { issue: context.create(:issue, project: context.project) } },
+    start_time_conditions: [["merge request that closes issue is created",
+                             -> (context, data) do
+                               context.create_merge_request_closing_issue(data[:issue])
+                             end]],
+    end_time_conditions:   [["merge request that closes issue is merged",
+                             -> (context, data) do
+                               context.merge_merge_requests_closing_issue(data[:issue])
+                             end]],
+    post_fn: -> (context, data) { context.deploy_master })
+
+  context "when a regular merge request (that doesn't close the issue) is created and merged" do
+    it "returns nil" do
+      5.times do
+        MergeRequests::MergeService.new(project, user).execute(create(:merge_request))
+
+        deploy_master
+      end
+
+      expect(subject.review).to be_nil
+    end
+  end
+end
diff --git a/spec/models/cycle_analytics/staging_spec.rb b/spec/models/cycle_analytics/staging_spec.rb
new file mode 100644
index 00000000000..af1c4477ddb
--- /dev/null
+++ b/spec/models/cycle_analytics/staging_spec.rb
@@ -0,0 +1,64 @@
+require 'spec_helper'
+
+describe 'CycleAnalytics#staging', feature: true do
+  extend CycleAnalyticsHelpers::TestGeneration
+
+  let(:project) { create(:project) }
+  let(:from_date) { 10.days.ago }
+  let(:user) { create(:user, :admin) }
+  subject { CycleAnalytics.new(project, from: from_date) }
+
+  generate_cycle_analytics_spec(
+    phase: :staging,
+    data_fn: lambda do |context|
+      issue = context.create(:issue, project: context.project)
+      { issue: issue, merge_request: context.create_merge_request_closing_issue(issue) }
+    end,
+    start_time_conditions: [["merge request that closes issue is merged",
+                             -> (context, data) do
+                               context.merge_merge_requests_closing_issue(data[:issue])
+                             end ]],
+    end_time_conditions:   [["merge request that closes issue is deployed to production",
+                             -> (context, data) do
+                               context.deploy_master
+                             end],
+                            ["production deploy happens after merge request is merged (along with other changes)",
+                             lambda do |context, data|
+                               # Make other changes on master
+                               sha = context.project.repository.commit_file(
+                                 context.user,
+                                 context.random_git_name,
+                                 "content",
+                                 "commit message",
+                                 'master',
+                                 false)
+                               context.project.repository.commit(sha)
+
+                               context.deploy_master
+                             end]])
+
+  context "when a regular merge request (that doesn't close the issue) is merged and deployed" do
+    it "returns nil" do
+      5.times do
+        merge_request = create(:merge_request)
+        MergeRequests::MergeService.new(project, user).execute(merge_request)
+        deploy_master
+      end
+
+      expect(subject.staging).to be_nil
+    end
+  end
+
+  context "when the deployment happens to a non-production environment" do
+    it "returns nil" do
+      5.times do
+        issue = create(:issue, project: project)
+        merge_request = create_merge_request_closing_issue(issue)
+        MergeRequests::MergeService.new(project, user).execute(merge_request)
+        deploy_master(environment: 'staging')
+      end
+
+      expect(subject.staging).to be_nil
+    end
+  end
+end
diff --git a/spec/models/cycle_analytics/summary_spec.rb b/spec/models/cycle_analytics/summary_spec.rb
new file mode 100644
index 00000000000..743bc2da33f
--- /dev/null
+++ b/spec/models/cycle_analytics/summary_spec.rb
@@ -0,0 +1,53 @@
+require 'spec_helper'
+
+describe CycleAnalytics::Summary, models: true do
+  let(:project) { create(:project) }
+  let(:from) { Time.now }
+  let(:user) { create(:user, :admin) }
+  subject { described_class.new(project, from: from) }
+
+  describe "#new_issues" do
+    it "finds the number of issues created after the 'from date'" do
+      Timecop.freeze(5.days.ago) { create(:issue, project: project) }
+      Timecop.freeze(5.days.from_now) { create(:issue, project: project) }
+
+      expect(subject.new_issues).to eq(1)
+    end
+
+    it "doesn't find issues from other projects" do
+      Timecop.freeze(5.days.from_now) { create(:issue, project: create(:project)) }
+
+      expect(subject.new_issues).to eq(0)
+    end
+  end
+
+  describe "#commits" do
+    it "finds the number of commits created after the 'from date'" do
+      Timecop.freeze(5.days.ago) { create_commit("Test message", project, user, 'master') }
+      Timecop.freeze(5.days.from_now) { create_commit("Test message", project, user, 'master') }
+
+      expect(subject.commits).to eq(1)
+    end
+
+    it "doesn't find commits from other projects" do
+      Timecop.freeze(5.days.from_now) { create_commit("Test message", create(:project), user, 'master') }
+
+      expect(subject.commits).to eq(0)
+    end
+  end
+
+  describe "#deploys" do
+    it "finds the number of deploys made created after the 'from date'" do
+      Timecop.freeze(5.days.ago) { create(:deployment, project: project) }
+      Timecop.freeze(5.days.from_now) { create(:deployment, project: project) }
+
+      expect(subject.deploys).to eq(1)
+    end
+
+    it "doesn't find commits from other projects" do
+      Timecop.freeze(5.days.from_now) { create(:deployment, project: create(:project)) }
+
+      expect(subject.deploys).to eq(0)
+    end
+  end
+end
diff --git a/spec/models/cycle_analytics/test_spec.rb b/spec/models/cycle_analytics/test_spec.rb
new file mode 100644
index 00000000000..89ace0b2742
--- /dev/null
+++ b/spec/models/cycle_analytics/test_spec.rb
@@ -0,0 +1,94 @@
+require 'spec_helper'
+
+describe 'CycleAnalytics#test', feature: true do
+  extend CycleAnalyticsHelpers::TestGeneration
+
+  let(:project) { create(:project) }
+  let(:from_date) { 10.days.ago }
+  let(:user) { create(:user, :admin) }
+  subject { CycleAnalytics.new(project, from: from_date) }
+
+  generate_cycle_analytics_spec(
+    phase: :test,
+    data_fn: lambda do |context|
+      issue = context.create(:issue, project: context.project)
+      merge_request = context.create_merge_request_closing_issue(issue)
+      pipeline = context.create(:ci_pipeline, ref: merge_request.source_branch, sha: merge_request.diff_head_sha, project: context.project)
+      { pipeline: pipeline, issue: issue }
+    end,
+    start_time_conditions: [["pipeline is started", -> (context, data) { data[:pipeline].run! }]],
+    end_time_conditions:   [["pipeline is finished", -> (context, data) { data[:pipeline].succeed! }]],
+    post_fn: -> (context, data) do
+      context.merge_merge_requests_closing_issue(data[:issue])
+      context.deploy_master
+    end)
+
+  context "when the pipeline is for a regular merge request (that doesn't close an issue)" do
+    it "returns nil" do
+      5.times do
+        issue = create(:issue, project: project)
+        merge_request = create_merge_request_closing_issue(issue)
+        pipeline = create(:ci_pipeline, ref: "refs/heads/#{merge_request.source_branch}", sha: merge_request.diff_head_sha)
+
+        pipeline.run!
+        pipeline.succeed!
+
+        merge_merge_requests_closing_issue(issue)
+        deploy_master
+      end
+
+      expect(subject.test).to be_nil
+    end
+  end
+
+  context "when the pipeline is not for a merge request" do
+    it "returns nil" do
+      5.times do
+        pipeline = create(:ci_pipeline, ref: "refs/heads/master", sha: project.repository.commit('master').sha)
+
+        pipeline.run!
+        pipeline.succeed!
+
+        deploy_master
+      end
+
+      expect(subject.test).to be_nil
+    end
+  end
+
+  context "when the pipeline is dropped (failed)" do
+    it "returns nil" do
+      5.times do
+        issue = create(:issue, project: project)
+        merge_request = create_merge_request_closing_issue(issue)
+        pipeline = create(:ci_pipeline, ref: "refs/heads/#{merge_request.source_branch}", sha: merge_request.diff_head_sha)
+
+        pipeline.run!
+        pipeline.drop!
+
+        merge_merge_requests_closing_issue(issue)
+        deploy_master
+      end
+
+      expect(subject.test).to be_nil
+    end
+  end
+
+  context "when the pipeline is cancelled" do
+    it "returns nil" do
+      5.times do
+        issue = create(:issue, project: project)
+        merge_request = create_merge_request_closing_issue(issue)
+        pipeline = create(:ci_pipeline, ref: "refs/heads/#{merge_request.source_branch}", sha: merge_request.diff_head_sha)
+
+        pipeline.run!
+        pipeline.cancel!
+
+        merge_merge_requests_closing_issue(issue)
+        deploy_master
+      end
+
+      expect(subject.test).to be_nil
+    end
+  end
+end
diff --git a/spec/models/issue/metrics_spec.rb b/spec/models/issue/metrics_spec.rb
new file mode 100644
index 00000000000..e170b087ebc
--- /dev/null
+++ b/spec/models/issue/metrics_spec.rb
@@ -0,0 +1,55 @@
+require 'spec_helper'
+
+describe Issue::Metrics, models: true do
+  let(:project) { create(:project) }
+
+  subject { create(:issue, project: project) }
+
+  describe "when recording the default set of issue metrics on issue save" do
+    context "milestones" do
+      it "records the first time an issue is associated with a milestone" do
+        time = Time.now
+        Timecop.freeze(time) { subject.update(milestone: create(:milestone)) }
+        metrics = subject.metrics
+
+        expect(metrics).to be_present
+        expect(metrics.first_associated_with_milestone_at).to be_within(1.second).of(time)
+      end
+
+      it "does not record the second time an issue is associated with a milestone" do
+        time = Time.now
+        Timecop.freeze(time) { subject.update(milestone: create(:milestone)) }
+        Timecop.freeze(time + 2.hours) { subject.update(milestone: nil) }
+        Timecop.freeze(time + 6.hours) { subject.update(milestone: create(:milestone)) }
+        metrics = subject.metrics
+
+        expect(metrics).to be_present
+        expect(metrics.first_associated_with_milestone_at).to be_within(1.second).of(time)
+      end
+    end
+
+    context "list labels" do
+      it "records the first time an issue is associated with a list label" do
+        list_label = create(:label, lists: [create(:list)])
+        time = Time.now
+        Timecop.freeze(time) { subject.update(label_ids: [list_label.id]) }
+        metrics = subject.metrics
+
+        expect(metrics).to be_present
+        expect(metrics.first_added_to_board_at).to be_within(1.second).of(time)
+      end
+
+      it "does not record the second time an issue is associated with a list label" do
+        time = Time.now
+        first_list_label = create(:label, lists: [create(:list)])
+        Timecop.freeze(time) { subject.update(label_ids: [first_list_label.id]) }
+        second_list_label = create(:label, lists: [create(:list)])
+        Timecop.freeze(time + 5.hours) { subject.update(label_ids: [second_list_label.id]) }
+        metrics = subject.metrics
+
+        expect(metrics).to be_present
+        expect(metrics.first_added_to_board_at).to be_within(1.second).of(time)
+      end
+    end
+  end
+end
diff --git a/spec/models/merge_request/metrics_spec.rb b/spec/models/merge_request/metrics_spec.rb
new file mode 100644
index 00000000000..a79dd215d41
--- /dev/null
+++ b/spec/models/merge_request/metrics_spec.rb
@@ -0,0 +1,18 @@
+require 'spec_helper'
+
+describe MergeRequest::Metrics, models: true do
+  let(:project) { create(:project) }
+
+  subject { create(:merge_request, source_project: project) }
+
+  describe "when recording the default set of metrics on merge request save" do
+    it "records the merge time" do
+      time = Time.now
+      Timecop.freeze(time) { subject.mark_as_merged }
+      metrics = subject.metrics
+
+      expect(metrics).to be_present
+      expect(metrics.merged_at).to be_within(1.second).of(time)
+    end
+  end
+end