Added relationships between Release and Milestone

Modified schema via migrations.
Added one-to-one relationship between the two models.
Added changelog file

10 files changed, 216 insertions, 0 deletions

diff --git a/spec/factories/milestone_releases.rb b/spec/factories/milestone_releases.rb
new file mode 100644
index 00000000000..08e109480ab
--- /dev/null
+++ b/spec/factories/milestone_releases.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :milestone_release do
+    milestone
+    release
+
+    before(:create, :build) do |mr|
+      project = create(:project)
+      mr.milestone.project = project
+      mr.release.project = project
+    end
+  end
+end
diff --git a/spec/fixtures/api/schemas/public_api/v4/release.json b/spec/fixtures/api/schemas/public_api/v4/release.json
index ec3fa59cdb1..078b1c0b982 100644
--- a/spec/fixtures/api/schemas/public_api/v4/release.json
+++ b/spec/fixtures/api/schemas/public_api/v4/release.json
@@ -15,6 +15,7 @@
     "author": {
       "oneOf": [{ "type": "null" }, { "$ref": "user/basic.json" }]
     },
+    "milestone": { "type": "string" },
     "assets": {
       "required": ["count", "links", "sources"],
       "properties": {
diff --git a/spec/lib/gitlab/import_export/all_models.yml b/spec/lib/gitlab/import_export/all_models.yml
index ec4a6ef05b9..c6aa4a2482c 100644
--- a/spec/lib/gitlab/import_export/all_models.yml
+++ b/spec/lib/gitlab/import_export/all_models.yml
@@ -62,6 +62,8 @@ milestone:
 - participants
 - events
 - boards
+- milestone_release
+- release
 snippets:
 - author
 - project
@@ -72,6 +74,8 @@ releases:
 - author
 - project
 - links
+- milestone_release
+- milestone
 links:
 - release
 project_members:
@@ -484,3 +488,6 @@ lists:
 - board
 - label
 - list_user_preferences
+milestone_releases:
+- milestone
+- release
diff --git a/spec/models/milestone_release_spec.rb b/spec/models/milestone_release_spec.rb
new file mode 100644
index 00000000000..d6f73275977
--- /dev/null
+++ b/spec/models/milestone_release_spec.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe MilestoneRelease do
+  let(:project) { create(:project) }
+  let(:release) { create(:release, project: project) }
+  let(:milestone) { create(:milestone, project: project) }
+
+  subject { build(:milestone_release, release: release, milestone: milestone) }
+
+  describe 'associations' do
+    it { is_expected.to belong_to(:milestone) }
+    it { is_expected.to belong_to(:release) }
+  end
+
+  describe 'validations' do
+    it { is_expected.to validate_uniqueness_of(:milestone_id).scoped_to(:release_id) }
+
+    context 'when milestone and release do not have the same project' do
+      it 'is not valid' do
+        other_project = create(:project)
+        release = build(:release, project: other_project)
+        milestone_release = described_class.new(milestone: milestone, release: release)
+        expect(milestone_release).not_to be_valid
+      end
+    end
+
+    context 'when milestone and release have the same project' do
+      it 'is valid' do
+        milestone_release = described_class.new(milestone: milestone, release: release)
+        expect(milestone_release).to be_valid
+      end
+    end
+  end
+end
diff --git a/spec/models/milestone_spec.rb b/spec/models/milestone_spec.rb
index 3704a2d468d..64030f5b92a 100644
--- a/spec/models/milestone_spec.rb
+++ b/spec/models/milestone_spec.rb
@@ -54,11 +54,31 @@ describe Milestone do
         expect(milestone.errors[:due_date]).to include("date must not be after 9999-12-31")
       end
     end
+
+    describe 'milestone_release' do
+      let(:milestone) { build(:milestone, project: project) }
+
+      context 'when it is tied to a release for another project' do
+        it 'creates a validation error' do
+          other_project = create(:project)
+          milestone.release = build(:release, project: other_project)
+          expect(milestone).not_to be_valid
+        end
+      end
+
+      context 'when it is tied to a release for the same project' do
+        it 'is valid' do
+          milestone.release = build(:release, project: project)
+          expect(milestone).to be_valid
+        end
+      end
+    end
   end
 
   describe "Associations" do
     it { is_expected.to belong_to(:project) }
     it { is_expected.to have_many(:issues) }
+    it { is_expected.to have_one(:release) }
   end
 
   let(:project) { create(:project, :public) }
diff --git a/spec/models/release_spec.rb b/spec/models/release_spec.rb
index e9d846e7291..29ce9f762b0 100644
--- a/spec/models/release_spec.rb
+++ b/spec/models/release_spec.rb
@@ -13,6 +13,7 @@ RSpec.describe Release do
     it { is_expected.to belong_to(:project) }
     it { is_expected.to belong_to(:author).class_name('User') }
     it { is_expected.to have_many(:links).class_name('Releases::Link') }
+    it { is_expected.to have_one(:milestone) }
   end
 
   describe 'validation' do
@@ -34,6 +35,20 @@ RSpec.describe Release do
         expect(existing_release_without_name.name).to be_nil
       end
     end
+
+    context 'when a release is tied to a milestone for another project' do
+      it 'creates a validation error' do
+        release.milestone = build(:milestone, project: create(:project))
+        expect(release).not_to be_valid
+      end
+    end
+
+    context 'when a release is tied to a milestone linked to the same project' do
+      it 'is valid' do
+        release.milestone = build(:milestone, project: project)
+        expect(release).to be_valid
+      end
+    end
   end
 
   describe '#assets_count' do
diff --git a/spec/services/milestones/destroy_service_spec.rb b/spec/services/milestones/destroy_service_spec.rb
index 3a22e4d4f92..ff1e1256166 100644
--- a/spec/services/milestones/destroy_service_spec.rb
+++ b/spec/services/milestones/destroy_service_spec.rb
@@ -65,5 +65,19 @@ describe Milestones::DestroyService do
         expect { service.execute(group_milestone) }.not_to change { Event.count }
       end
     end
+
+    context 'when a release is tied to a milestone' do
+      it 'destroys the milestone but not the associated release' do
+        release = create(
+          :release,
+          tag: 'v1.0',
+          project: project,
+          milestone: milestone
+        )
+
+        expect { service.execute(milestone) }.not_to change { Release.count }
+        expect(release.reload).to be_persisted
+      end
+    end
   end
 end
diff --git a/spec/services/releases/create_service_spec.rb b/spec/services/releases/create_service_spec.rb
index e26676cdd55..5c9d6537df1 100644
--- a/spec/services/releases/create_service_spec.rb
+++ b/spec/services/releases/create_service_spec.rb
@@ -72,6 +72,15 @@ describe Releases::CreateService do
         expect(project.releases.find_by(tag: tag_name).description).to eq(description)
       end
     end
+
+    context 'when a passed-in milestone does not exist for this project' do
+      it 'raises an error saying the milestone is inexistent' do
+        service = described_class.new(project, user, params.merge!({ milestone: 'v111.0' }))
+        result = service.execute
+        expect(result[:status]).to eq(:error)
+        expect(result[:message]).to eq('Milestone does not exist')
+      end
+    end
   end
 
   describe '#find_or_build_release' do
@@ -80,5 +89,58 @@ describe Releases::CreateService do
 
       expect(project.releases.count).to eq(0)
     end
+
+    context 'when existing milestone is passed in' do
+      let(:title) { 'v1.0' }
+      let(:milestone) { create(:milestone, :active, project: project, title: title) }
+      let(:params_with_milestone) { params.merge!({ milestone: title }) }
+
+      it 'creates a release and ties this milestone to it' do
+        service = described_class.new(milestone.project, user, params_with_milestone)
+        result = service.execute
+
+        expect(project.releases.count).to eq(1)
+        expect(result[:status]).to eq(:success)
+
+        release = project.releases.last
+
+        expect(release.milestone).to eq(milestone)
+      end
+
+      context 'when another release was previously created with that same milestone linked' do
+        it 'also creates another release tied to that same milestone' do
+          other_release = create(:release, milestone: milestone, project: project, tag: 'v1.0')
+          service = described_class.new(milestone.project, user, params_with_milestone)
+          service.execute
+          release = project.releases.last
+
+          expect(release.milestone).to eq(milestone)
+          expect(other_release.milestone).to eq(milestone)
+          expect(release.id).not_to eq(other_release.id)
+        end
+      end
+    end
+
+    context 'when no milestone is passed in' do
+      it 'creates a release without a milestone tied to it' do
+        expect(params.key? :milestone).to be_falsey
+        service.execute
+        release = project.releases.last
+        expect(release.milestone).to be_nil
+      end
+
+      it 'does not create any new MilestoneRelease object' do
+        expect { service.execute }.not_to change { MilestoneRelease.count }
+      end
+    end
+
+    context 'when an empty value is passed as a milestone' do
+      it 'creates a release without a milestone tied to it' do
+        service = described_class.new(project, user, params.merge!({ milestone: '' }))
+        service.execute
+        release = project.releases.last
+        expect(release.milestone).to be_nil
+      end
+    end
   end
 end
diff --git a/spec/services/releases/destroy_service_spec.rb b/spec/services/releases/destroy_service_spec.rb
index f4c901e6585..c3172e5edbc 100644
--- a/spec/services/releases/destroy_service_spec.rb
+++ b/spec/services/releases/destroy_service_spec.rb
@@ -57,5 +57,15 @@ describe Releases::DestroyService do
                                http_status: 403)
       end
     end
+
+    context 'when a milestone is tied to the release' do
+      let!(:milestone) { create(:milestone, :active, project: project, title: 'v1.0') }
+      let!(:release) { create(:release, milestone: milestone, project: project, tag: tag) }
+
+      it 'destroys the release but leave the milestone intact' do
+        expect { subject }.not_to change { Milestone.count }
+        expect(milestone.reload).to be_persisted
+      end
+    end
   end
 end
diff --git a/spec/services/releases/update_service_spec.rb b/spec/services/releases/update_service_spec.rb
index 14e6a5f13c8..944f3d8c9ad 100644
--- a/spec/services/releases/update_service_spec.rb
+++ b/spec/services/releases/update_service_spec.rb
@@ -48,5 +48,42 @@ describe Releases::UpdateService do
 
       it_behaves_like 'a failed update'
     end
+
+    context 'when a milestone is passed in' do
+      let(:old_title) { 'v1.0' }
+      let(:new_title) { 'v2.0' }
+      let(:milestone) { create(:milestone, project: project, title: old_title) }
+      let(:new_milestone) { create(:milestone, project: project, title: new_title) }
+      let(:params_with_milestone) { params.merge!({ milestone: new_title }) }
+
+      before do
+        release.milestone = milestone
+        release.save!
+
+        described_class.new(new_milestone.project, user, params_with_milestone).execute
+        release.reload
+      end
+
+      it 'updates the related milestone accordingly' do
+        expect(release.milestone.title).to eq(new_title)
+      end
+    end
+
+    context "when an 'empty' milestone is passed in" do
+      let(:milestone) { create(:milestone, project: project, title: 'v1.0') }
+      let(:params_with_empty_milestone) { params.merge!({ milestone: '' }) }
+
+      before do
+        release.milestone = milestone
+        release.save!
+
+        described_class.new(milestone.project, user, params_with_empty_milestone).execute
+        release.reload
+      end
+
+      it 'removes the old milestone and does not associate any new milestone' do
+        expect(release.milestone).to be_nil
+      end
+    end
   end
 end