[CE] Support multiple assignees for merge requestsosw-multi-assignees-merge-requests

Backports https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/10161
(code out of ee/ folder).

6 files changed, 180 insertions, 63 deletions

diff --git a/spec/models/ci/pipeline_spec.rb b/spec/models/ci/pipeline_spec.rb
index 83b0f172f03..f3e78630c1b 100644
--- a/spec/models/ci/pipeline_spec.rb
+++ b/spec/models/ci/pipeline_spec.rb
@@ -684,12 +684,12 @@ describe Ci::Pipeline, :mailer do
                source_branch: 'feature',
                target_project: project,
                target_branch: 'master',
-               assignee: assignee,
+               assignees: assignees,
                milestone: milestone,
                labels: labels)
       end
 
-      let(:assignee) { create(:user) }
+      let(:assignees) { create_list(:user, 2) }
       let(:milestone) { create(:milestone, project: project) }
       let(:labels) { create_list(:label, 2) }
 
@@ -710,7 +710,7 @@ describe Ci::Pipeline, :mailer do
             'CI_MERGE_REQUEST_SOURCE_BRANCH_NAME' => merge_request.source_branch.to_s,
             'CI_MERGE_REQUEST_SOURCE_BRANCH_SHA' => pipeline.source_sha.to_s,
             'CI_MERGE_REQUEST_TITLE' => merge_request.title,
-            'CI_MERGE_REQUEST_ASSIGNEES' => assignee.username,
+            'CI_MERGE_REQUEST_ASSIGNEES' => merge_request.assignee_username_list,
             'CI_MERGE_REQUEST_MILESTONE' => milestone.title,
             'CI_MERGE_REQUEST_LABELS' => labels.map(&:title).join(','))
       end
@@ -730,7 +730,7 @@ describe Ci::Pipeline, :mailer do
       end
 
       context 'without assignee' do
-        let(:assignee) { nil }
+        let(:assignees) { [] }
 
         it 'does not expose assignee variable' do
           expect(subject.to_hash.keys).not_to include('CI_MERGE_REQUEST_ASSIGNEES')
diff --git a/spec/models/concerns/deprecated_assignee_spec.rb b/spec/models/concerns/deprecated_assignee_spec.rb
new file mode 100644
index 00000000000..e394de0aa34
--- /dev/null
+++ b/spec/models/concerns/deprecated_assignee_spec.rb
@@ -0,0 +1,160 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe DeprecatedAssignee do
+  let(:user) { create(:user) }
+
+  describe '#assignee_id=' do
+    it 'creates the merge_request_assignees relation' do
+      merge_request = create(:merge_request, assignee_id: user.id)
+
+      merge_request.reload
+
+      expect(merge_request.merge_request_assignees.count).to eq(1)
+    end
+
+    it 'nullifies the assignee_id column' do
+      merge_request = create(:merge_request, assignee_id: user.id)
+
+      merge_request.reload
+
+      expect(merge_request.read_attribute(:assignee_id)).to be_nil
+    end
+
+    context 'when relation already exists' do
+      it 'overwrites existing assignees' do
+        other_user = create(:user)
+        merge_request = create(:merge_request, assignee_id: nil)
+        merge_request.merge_request_assignees.create!(user_id: user.id)
+        merge_request.merge_request_assignees.create!(user_id: other_user.id)
+
+        expect { merge_request.update!(assignee_id: other_user.id) }
+          .to change { merge_request.reload.merge_request_assignees.count }
+          .from(2).to(1)
+      end
+    end
+  end
+
+  describe '#assignee=' do
+    it 'creates the merge_request_assignees relation' do
+      merge_request = create(:merge_request, assignee: user)
+
+      merge_request.reload
+
+      expect(merge_request.merge_request_assignees.count).to eq(1)
+    end
+
+    it 'nullifies the assignee_id column' do
+      merge_request = create(:merge_request, assignee: user)
+
+      merge_request.reload
+
+      expect(merge_request.read_attribute(:assignee_id)).to be_nil
+    end
+
+    context 'when relation already exists' do
+      it 'overwrites existing assignees' do
+        other_user = create(:user)
+        merge_request = create(:merge_request, assignee: nil)
+        merge_request.merge_request_assignees.create!(user_id: user.id)
+        merge_request.merge_request_assignees.create!(user_id: other_user.id)
+
+        expect { merge_request.update!(assignee: other_user) }
+          .to change { merge_request.reload.merge_request_assignees.count }
+          .from(2).to(1)
+      end
+    end
+  end
+
+  describe '#assignee_id' do
+    it 'returns the first assignee ID' do
+      other_user = create(:user)
+      merge_request = create(:merge_request, assignees: [user, other_user])
+
+      merge_request.reload
+
+      expect(merge_request.assignee_id).to eq(merge_request.assignee_ids.first)
+    end
+  end
+
+  describe '#assignees' do
+    context 'when assignee_id exists and there is no relation' do
+      it 'creates the relation' do
+        merge_request = create(:merge_request, assignee_id: nil)
+        merge_request.update_column(:assignee_id, user.id)
+
+        expect { merge_request.assignees }.to change { merge_request.merge_request_assignees.count }.from(0).to(1)
+      end
+
+      it 'nullifies the assignee_id' do
+        merge_request = create(:merge_request, assignee_id: nil)
+        merge_request.update_column(:assignee_id, user.id)
+
+        expect { merge_request.assignees }
+          .to change { merge_request.read_attribute(:assignee_id) }
+          .from(user.id).to(nil)
+      end
+    end
+
+    context 'when DB is read-only' do
+      before do
+        allow(Gitlab::Database).to receive(:read_only?) { true }
+      end
+
+      it 'returns a users relation' do
+        merge_request = create(:merge_request, assignee_id: user.id)
+
+        expect(merge_request.assignees).to be_a(ActiveRecord::Relation)
+        expect(merge_request.assignees).to eq([user])
+      end
+
+      it 'returns an empty relation if no assignee_id is set' do
+        merge_request = create(:merge_request, assignee_id: nil)
+
+        expect(merge_request.assignees).to be_a(ActiveRecord::Relation)
+        expect(merge_request.assignees).to eq([])
+      end
+    end
+  end
+
+  describe '#assignee_ids' do
+    context 'when assignee_id exists and there is no relation' do
+      it 'creates the relation' do
+        merge_request = create(:merge_request, assignee_id: nil)
+        merge_request.update_column(:assignee_id, user.id)
+
+        expect { merge_request.assignee_ids }.to change { merge_request.merge_request_assignees.count }.from(0).to(1)
+      end
+
+      it 'nullifies the assignee_id' do
+        merge_request = create(:merge_request, assignee_id: nil)
+        merge_request.update_column(:assignee_id, user.id)
+
+        expect { merge_request.assignee_ids }
+          .to change { merge_request.read_attribute(:assignee_id) }
+          .from(user.id).to(nil)
+      end
+    end
+
+    context 'when DB is read-only' do
+      before do
+        allow(Gitlab::Database).to receive(:read_only?) { true }
+      end
+
+      it 'returns a list of user IDs' do
+        merge_request = create(:merge_request, assignee_id: user.id)
+
+        expect(merge_request.assignee_ids).to be_a(Array)
+        expect(merge_request.assignee_ids).to eq([user.id])
+      end
+
+      it 'returns an empty relation if no assignee_id is set' do
+        merge_request = create(:merge_request, assignee_id: nil)
+
+        expect(merge_request.assignee_ids).to be_a(Array)
+        expect(merge_request.assignee_ids).to eq([])
+      end
+    end
+  end
+end
diff --git a/spec/models/concerns/issuable_spec.rb b/spec/models/concerns/issuable_spec.rb
index 27ed298ae08..64f02978d79 100644
--- a/spec/models/concerns/issuable_spec.rb
+++ b/spec/models/concerns/issuable_spec.rb
@@ -502,8 +502,8 @@ describe Issuable do
       let(:user2) { create(:user) }
 
       before do
-        merge_request.update(assignee: user)
-        merge_request.update(assignee: user2)
+        merge_request.update(assignees: [user])
+        merge_request.update(assignees: [user, user2])
         expect(Gitlab::HookData::IssuableBuilder)
           .to receive(:new).with(merge_request).and_return(builder)
       end
@@ -512,8 +512,7 @@ describe Issuable do
         expect(builder).to receive(:build).with(
           user: user,
           changes: hash_including(
-            'assignee_id' => [user.id, user2.id],
-            'assignee' => [user.hook_attrs, user2.hook_attrs]
+            'assignees' => [[user.hook_attrs], [user.hook_attrs, user2.hook_attrs]]
           ))
 
         merge_request.to_hook_data(user, old_associations: { assignees: [user] })
diff --git a/spec/models/event_spec.rb b/spec/models/event_spec.rb
index d192fe70506..e91b5c4c86f 100644
--- a/spec/models/event_spec.rb
+++ b/spec/models/event_spec.rb
@@ -263,7 +263,7 @@ describe Event do
 
     context 'merge request diff note event' do
       let(:project) { create(:project, :public) }
-      let(:merge_request) { create(:merge_request, source_project: project, author: author, assignee: assignee) }
+      let(:merge_request) { create(:merge_request, source_project: project, author: author, assignees: [assignee]) }
       let(:note_on_merge_request) { create(:legacy_diff_note_on_merge_request, noteable: merge_request, project: project) }
       let(:target) { note_on_merge_request }
 
diff --git a/spec/models/merge_request_spec.rb b/spec/models/merge_request_spec.rb
index 6f34ef9c1bc..f61857ea5ff 100644
--- a/spec/models/merge_request_spec.rb
+++ b/spec/models/merge_request_spec.rb
@@ -13,7 +13,7 @@ describe MergeRequest do
     it { is_expected.to belong_to(:target_project).class_name('Project') }
     it { is_expected.to belong_to(:source_project).class_name('Project') }
     it { is_expected.to belong_to(:merge_user).class_name("User") }
-    it { is_expected.to belong_to(:assignee) }
+    it { is_expected.to have_many(:assignees).through(:merge_request_assignees) }
     it { is_expected.to have_many(:merge_request_diffs) }
 
     context 'for forks' do
@@ -181,31 +181,6 @@ describe MergeRequest do
         expect(MergeRequest::Metrics.count).to eq(1)
       end
     end
-
-    describe '#refresh_merge_request_assignees' do
-      set(:user) { create(:user) }
-
-      it 'creates merge request assignees relation upon MR creation' do
-        merge_request = create(:merge_request, assignee: nil)
-
-        expect(merge_request.merge_request_assignees).to be_empty
-
-        expect { merge_request.update!(assignee: user) }
-          .to change { merge_request.reload.merge_request_assignees.count }
-          .from(0).to(1)
-      end
-
-      it 'updates merge request assignees relation upon MR assignee change' do
-        another_user = create(:user)
-        merge_request = create(:merge_request, assignee: user)
-
-        expect { merge_request.update!(assignee: another_user) }
-          .to change { merge_request.reload.merge_request_assignees.first.assignee }
-          .from(user).to(another_user)
-
-        expect(merge_request.merge_request_assignees.count).to eq(1)
-      end
-    end
   end
 
   describe 'respond to' do
@@ -337,34 +312,18 @@ describe MergeRequest do
   describe '#card_attributes' do
     it 'includes the author name' do
       allow(subject).to receive(:author).and_return(double(name: 'Robert'))
-      allow(subject).to receive(:assignee).and_return(nil)
+      allow(subject).to receive(:assignees).and_return([])
 
       expect(subject.card_attributes)
-        .to eq({ 'Author' => 'Robert', 'Assignee' => nil })
+        .to eq({ 'Author' => 'Robert', 'Assignee' => "" })
     end
 
-    it 'includes the assignee name' do
+    it 'includes the assignees name' do
       allow(subject).to receive(:author).and_return(double(name: 'Robert'))
-      allow(subject).to receive(:assignee).and_return(double(name: 'Douwe'))
+      allow(subject).to receive(:assignees).and_return([double(name: 'Douwe'), double(name: 'Robert')])
 
       expect(subject.card_attributes)
-        .to eq({ 'Author' => 'Robert', 'Assignee' => 'Douwe' })
-    end
-  end
-
-  describe '#assignee_ids' do
-    it 'returns an array of the assigned user id' do
-      subject.assignee_id = 123
-
-      expect(subject.assignee_ids).to eq([123])
-    end
-  end
-
-  describe '#assignee_ids=' do
-    it 'sets assignee_id to the last id in the array' do
-      subject.assignee_ids = [123, 456]
-
-      expect(subject.assignee_id).to eq(456)
+        .to eq({ 'Author' => 'Robert', 'Assignee' => 'Douwe and Robert' })
     end
   end
 
@@ -372,7 +331,7 @@ describe MergeRequest do
     let(:user) { create(:user) }
 
     it 'returns true for a user that is assigned to a merge request' do
-      subject.assignee = user
+      subject.assignees = [user]
 
       expect(subject.assignee_or_author?(user)).to eq(true)
     end
@@ -1949,15 +1908,14 @@ describe MergeRequest do
     it 'updates when assignees change' do
       user1 = create(:user)
       user2 = create(:user)
-      mr = create(:merge_request, assignee: user1)
+      mr = create(:merge_request, assignees: [user1])
       mr.project.add_developer(user1)
       mr.project.add_developer(user2)
 
       expect(user1.assigned_open_merge_requests_count).to eq(1)
       expect(user2.assigned_open_merge_requests_count).to eq(0)
 
-      mr.assignee = user2
-      mr.save
+      mr.assignees = [user2]
 
       expect(user1.assigned_open_merge_requests_count).to eq(0)
       expect(user2.assigned_open_merge_requests_count).to eq(1)
diff --git a/spec/models/user_spec.rb b/spec/models/user_spec.rb
index a45a2737b13..d1338e34bb8 100644
--- a/spec/models/user_spec.rb
+++ b/spec/models/user_spec.rb
@@ -2816,9 +2816,9 @@ describe User do
       project = create(:project, :public)
       archived_project = create(:project, :public, :archived)
 
-      create(:merge_request, source_project: project, author: user, assignee: user)
-      create(:merge_request, :closed, source_project: project, author: user, assignee: user)
-      create(:merge_request, source_project: archived_project, author: user, assignee: user)
+      create(:merge_request, source_project: project, author: user, assignees: [user])
+      create(:merge_request, :closed, source_project: project, author: user, assignees: [user])
+      create(:merge_request, source_project: archived_project, author: user, assignees: [user])
 
       expect(user.assigned_open_merge_requests_count(force: true)).to eq 1
     end