Merge branch 'multiple_assignees_review' into 'multiple-assignees-fe-sidebar'

# Conflicts:
#   app/assets/stylesheets/framework/avatar.scss

app/assets/stylesheets/framework/avatar.scss

@@ -101,6 +101,6 @@
   border-radius: 1em;
   font-family: $regular_font;
   font-size: 9px;
-  line-height: 17px;
+  line-height: 16px;
   text-align: center;
-}
+}
\ No newline at end of file

app/assets/stylesheets/framework/lists.scss

@@ -261,6 +261,7 @@ ul.controls {
       .avatar-inline {
         margin-left: 0;
         margin-right: 0;
+        margin-bottom: 0;
       }
     }
   }

app/assets/stylesheets/pages/issuable.scss

@@ -575,6 +575,16 @@
         vertical-align: text-top;
       }
     }
+
+    .avatar-counter {
+      display: inline-block;
+      vertical-align: middle;
+      min-width: 16px;
+      line-height: 14px;
+      height: 16px;
+      padding-left: 2px;
+      padding-right: 2px;
+    }
   }
 }
 

app/controllers/concerns/issuable_collections.rb

@@ -40,7 +40,7 @@ module IssuableCollections
   end
 
   def issues_collection
-    issues_finder.execute.preload(:project, :author, :labels, :milestone, project: :namespace)
+    issues_finder.execute.preload(:project, :author, :assignees, :labels, :milestone, project: :namespace)
   end
 
   def merge_requests_collection

app/models/concerns/elastic/issues_search.rb

@@ -17,7 +17,14 @@ module Elastic
         indexes :state,       type: :text
         indexes :project_id,  type: :integer
         indexes :author_id,   type: :integer
+
+        # The field assignee_id does not exist in issues table anymore.
+        # Nevertheless we'll keep this field as is because we don't want users to rebuild index
+        # + the ES treats arrays transparently so
+        # to any integer field you can write any array of integers and you don't have to change mapping.
+        # More over you can query those items just like a single integer value.
         indexes :assignee_id, type: :integer
+
         indexes :confidential, type: :boolean
       end
 
@@ -26,10 +33,12 @@ module Elastic
 
         # We don't use as_json(only: ...) because it calls all virtual and serialized attributtes
         # https://gitlab.com/gitlab-org/gitlab-ee/issues/349
-        [:id, :iid, :title, :description, :created_at, :updated_at, :state, :project_id, :author_id, :assignee_id, :confidential].each do |attr|
+        [:id, :iid, :title, :description, :created_at, :updated_at, :state, :project_id, :author_id, :confidential].each do |attr|
           data[attr.to_s] = safely_read_attribute_for_elasticsearch(attr)
         end
 
+        data['assignee_id'] = safely_read_attribute_for_elasticsearch(:assignee_ids)
+
         data
       end
 

app/models/concerns/elastic/notes_search.rb

@@ -34,7 +34,7 @@ module Elastic
 
         if noteable.is_a?(Issue)
           data['issue'] = {
-            assignee_id: noteable.assignee_id,
+            assignee_id: noteable.assignee_ids,
             author_id: noteable.author_id,
             confidential: noteable.confidential
           }

app/models/issue.rb

@@ -136,14 +136,6 @@ class Issue < ActiveRecord::Base
               "id DESC")
   end
 
-  def update_assignee_cache_counts
-    return true # TODO implement it properly
-    # make sure we flush the cache for both the old *and* new assignees(if they exist)
-    previous_assignee = User.find_by_id(assignee_id_was) if assignee_id_was
-    previous_assignee&.update_cache_counts
-    assignee&.update_cache_counts
-  end
-
   # Returns a Hash of attributes to be used for Twitter card metadata
   def card_attributes
     {

app/models/issue_assignee.rb

 class IssueAssignee < ActiveRecord::Base
-	belongs_to :issue
-	belongs_to :assignee, class_name: "User", foreign_key: :user_id
-end
\ No newline at end of file
+  extend Gitlab::CurrentSettings
+
+  belongs_to :issue
+  belongs_to :assignee, class_name: "User", foreign_key: :user_id
+
+  after_create :update_assignee_cache_counts
+  after_destroy :update_assignee_cache_counts
+
+  # EE-specific
+  after_create :update_elasticsearch_index
+  after_destroy :update_elasticsearch_index
+  # EE-specific
+
+  def update_assignee_cache_counts
+    assignee&.update_cache_counts
+  end
+
+  def update_elasticsearch_index
+    if current_application_settings.elasticsearch_indexing?
+      ElasticIndexerWorker.perform_async(
+        :update,
+        'Issue',
+        issue.id,
+        changed_fields: ['assignee_ids']
+      )
+    end
+  end
+end

app/models/merge_request.rb

@@ -189,10 +189,6 @@ class MergeRequest < ActiveRecord::Base
     work_in_progress?(title) ? title : "WIP: #{title}"
   end
 
-  def is_being_reassigned?
-    assignee_id_changed?
-  end
-
   def update_assignee_cache_counts
     # make sure we flush the cache for both the old *and* new assignees(if they exist)
     previous_assignee = User.find_by_id(assignee_id_was) if assignee_id_was
@@ -210,7 +206,7 @@ class MergeRequest < ActiveRecord::Base
 
   # This method is needed for compatibility with issues to not mess view and other code
   def assignees
-    assignee ? [assignee] : []
+    Array(assignee)
   end
 
   def assignee_or_author?(user)

app/services/issuable/bulk_update_service.rb

@@ -7,10 +7,14 @@ module Issuable
       ids = params.delete(:issuable_ids).split(",")
       items = model_class.where(id: ids)
 
-      %i(state_event milestone_id assignee_id add_label_ids remove_label_ids subscription_event).each do |key|
+      %i(state_event milestone_id assignee_id assignee_ids add_label_ids remove_label_ids subscription_event).each do |key|
         params.delete(key) unless params[key].present?
       end
 
+      if params[:assignee_ids] == [IssuableFinder::NONE.to_s]
+        params[:assignee_ids] = []
+      end
+
       items.each do |issuable|
         next unless can?(current_user, :"update_#{type}", issuable)
 

app/services/merge_requests/assign_issues_service.rb

@@ -14,7 +14,7 @@ module MergeRequests
 
     def execute
       assignable_issues.each do |issue|
-        Issues::UpdateService.new(issue.project, current_user, assignee_ids: current_user.id.to_s).execute(issue)
+        Issues::UpdateService.new(issue.project, current_user, assignee_ids: [current_user.id]).execute(issue)
       end
 
       {

app/services/notification_recipient_service.rb

@@ -8,7 +8,6 @@ class NotificationRecipientService
     @project = project
   end
 
-  # TODO: refactor this: previous_assignee argument can be a user object or an array which is not really nice
   def build_recipients(target, current_user, action: nil, previous_assignee: nil, skip_current_user: true)
     custom_action = build_custom_key(action, target)
 
@@ -29,7 +28,8 @@ class NotificationRecipientService
       recipients << previous_assignee if previous_assignee
       recipients << target.assignee
     when :reassign_issue
-      recipients.concat(previous_assignee) if previous_assignee.any?
+      previous_assignees = Array(previous_assignee)
+      recipients.concat(previous_assignees) if previous_assignees.any?
       recipients.concat(target.assignees)
     end
 

app/services/slash_commands/interpret_service.rb

@@ -89,17 +89,27 @@ module SlashCommands
       user = extract_references(assignee_param, :user).first
       user ||= User.find_by(username: assignee_param)
 
-      @updates[:assignee_id] = user.id if user
+      next unless user
+
+      if issuable.is_a?(Issue)
+        @updates[:assignee_ids] = [user.id]
+      else
+        @updates[:assignee_id] = user.id
+      end
     end
 
     desc 'Remove assignee'
     condition do
       issuable.persisted? &&
-        issuable.assignee_id? &&
+        issuable.assignees.any? &&
         current_user.can?(:"admin_#{issuable.to_ability_name}", project)
     end
     command :unassign do
-      @updates[:assignee_id] = nil
+      if issuable.is_a?(Issue)
+        @updates[:assignee_ids] = []
+      else
+        @updates[:assignee_id] = nil
+      end
     end
 
     desc 'Set milestone'

app/services/system_note_service.rb

@@ -68,13 +68,16 @@ module SystemNoteService
   #
   # Returns the created Note object
   def change_issue_assignees(issue, project, author, old_assignees)
-    # TODO: basic implementation, should be improved before merging the MR
     body =
       if issue.assignees.any? && old_assignees.any?
         unassigned_users = old_assignees - issue.assignees
         added_users = issue.assignees.to_a - old_assignees
 
-        "assigned to #{added_users.map(&:to_reference).to_sentence} and unassigned #{unassigned_users.map(&:to_reference).to_sentence}"
+        text_parts = []
+        text_parts << "assigned to #{added_users.map(&:to_reference).to_sentence}" if added_users.any?
+        text_parts << "unassigned #{unassigned_users.map(&:to_reference).to_sentence}" if unassigned_users.any?
+
+        text_parts.join(' and ')
       elsif old_assignees.any?
         "removed all assignees"
       elsif issue.assignees.any?
@@ -84,7 +87,6 @@ module SystemNoteService
     create_note(noteable: issue, project: project, author: author, note: body)
   end
 
-
   # Called when one or more labels on a Noteable are added and/or removed
   #
   # noteable       - Noteable object

app/services/todo_service.rb

@@ -270,7 +270,7 @@ class TodoService
     end
   end
 
-    def create_mention_todos(project, target, author, note = nil)
+  def create_mention_todos(project, target, author, note = nil)
     # Create Todos for directly addressed users
     directly_addressed_users = filter_directly_addressed_users(project, note || target, author)
     attributes = attributes_for_todo(project, target, author, Todo::DIRECTLY_ADDRESSED, note)

app/views/issues/_issue.atom.builder

@@ -26,8 +26,8 @@ xml.entry do
   if issue.assignees.any?
     xml.assignees do
       issue.assignees.each do |assignee|
-        xml.name ssignee.name
-        xml.email assignee.assignee_public_email
+        xml.name assignee.name
+        xml.email assignee.public_email
       end
     end
   end

app/views/projects/issues/_issue.html.haml

@@ -15,8 +15,7 @@
 
           - if issue.assignees.any?
             %li
-              - issue.assignees.each do |assignee|
-                = link_to_member(@project, assignee, name: false, title: "Assigned to :name")
+              = render 'shared/issuable/assignees', project: @project, issue: issue
 
           = render 'shared/issuable_meta_data', issuable: issue
 

app/views/shared/issuable/_assignees.html.haml

+- max_render = 3
+- max = [max_render, issue.assignees.length].min
+
+- issue.assignees.each_with_index do |assignee, index|
+  - if index < max
+    = link_to_member(@project, assignee, name: false, title: "Assigned to :name")
+
+- if issue.assignees.length > max_render
+  - counter = issue.assignees.length - max_render
+
+  %span{ class: 'avatar-counter has-tooltip', data: { container: 'body', placement: 'bottom', 'line-type' => 'old', 'original-title' => "+#{counter} more assignees" } }
+    - if counter < 99
+      = "+#{counter}"
+    - else
+      99+

app/workers/elastic_indexer_worker.rb

@@ -5,7 +5,7 @@ class ElasticIndexerWorker
 
   sidekiq_options queue: :elasticsearch, retry: 2
 
-  ISSUE_TRACKED_FIELDS = %w(assignee_id author_id confidential).freeze
+  ISSUE_TRACKED_FIELDS = %w(assignee_ids author_id confidential).freeze
 
   def perform(operation, class_name, record_id, options = {})
     return true unless current_application_settings.elasticsearch_indexing?

db/migrate/20170320171632_create_issue_assignees_table.rb

@@ -4,6 +4,8 @@
 class CreateIssueAssigneesTable < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
 
+  INDEX_NAME = 'index_issue_assignees_on_issue_id_and_user_id'
+
   # Set this constant to true if this migration requires downtime.
   DOWNTIME = false
 
@@ -23,12 +25,20 @@ class CreateIssueAssigneesTable < ActiveRecord::Migration
   # comments:
   # disable_ddl_transaction!
 
-  def change
+  def up
     create_table :issue_assignees do |t|
       t.references :user, foreign_key: { on_delete: :cascade }, index: true, null: false
       t.references :issue, foreign_key: { on_delete: :cascade }, null: false
     end
 
-    add_index :issue_assignees, [:issue_id, :user_id], unique: true
+    add_index :issue_assignees, [:issue_id, :user_id], unique: true, name: INDEX_NAME
+  end
+
+  def down
+    if index_exists?(:issue_assignees, name: INDEX_NAME)
+      remove_index :issue_assignees, name: INDEX_NAME
+    end
+
+    drop_table :issue_assignees
   end
 end

lib/api/entities.rb

@@ -279,7 +279,7 @@ module API
     class IssueBasic < ProjectEntity
       expose :label_names, as: :labels
       expose :milestone, using: Entities::Milestone
-      expose :assignee, :author, using: Entities::UserBasic
+      expose :assignees, :author, using: Entities::UserBasic
 
       expose :user_notes_count
       expose :upvotes, :downvotes

lib/api/issues.rb

@@ -31,7 +31,7 @@ module API
 
       params :issue_params do
         optional :description, type: String, desc: 'The description of an issue'
-        optional :assignee_id, type: Integer, desc: 'The ID of a user to assign issue'
+        optional :assignee_ids, type: Array[Integer], desc: 'The ID of a user to assign issue'
         optional :milestone_id, type: Integer, desc: 'The ID of a milestone to assign issue'
         optional :labels, type: String, desc: 'Comma-separated list of label names'
         optional :due_date, type: String, desc: 'Date string in the format YEAR-MONTH-DAY'
@@ -156,7 +156,7 @@ module API
                               desc: 'Date time when the issue was updated. Available only for admins and project owners.'
         optional :state_event, type: String, values: %w[reopen close], desc: 'State of the issue'
         use :issue_params
-        at_least_one_of :title, :description, :assignee_id, :milestone_id,
+        at_least_one_of :title, :description, :assignee_ids, :milestone_id,
                         :labels, :created_at, :due_date, :confidential, :state_event,
                         :weight
       end

lib/gitlab/chat_commands/presenters/issue_base.rb

@@ -22,7 +22,7 @@ module Gitlab
           [
             {
               title: "Assignee",
-              value: @resource.assignee ? @resource.assignee.name : "_None_",
+              value: @resource.assignees.any? ? @resource.assignees.first.name : "_None_",
               short: true
             },
             {

lib/gitlab/fogbugz_import/importer.rb

@@ -122,15 +122,15 @@ module Gitlab
           author_id = user_info(bug['ixPersonOpenedBy'])[:gitlab_id] || project.creator_id
 
           issue = Issue.create!(
-            iid:         bug['ixBug'],
-            project_id:  project.id,
-            title:       bug['sTitle'],
-            description: body,
-            author_id:   author_id,
-            assignee_id: assignee_id,
-            state:       bug['fOpen'] == 'true' ? 'opened' : 'closed',
-            created_at:  date,
-            updated_at:  DateTime.parse(bug['dtLastUpdated'])
+            iid:          bug['ixBug'],
+            project_id:   project.id,
+            title:        bug['sTitle'],
+            description:  body,
+            author_id:    author_id,
+            assignee_ids: [assignee_id],
+            state:        bug['fOpen'] == 'true' ? 'opened' : 'closed',
+            created_at:   date,
+            updated_at:   DateTime.parse(bug['dtLastUpdated'])
           )
 
           issue_labels = ::LabelsFinder.new(nil, project_id: project.id, title: labels).execute(skip_authorization: true)

lib/gitlab/github_import/issue_formatter.rb

@@ -10,7 +10,7 @@ module Gitlab
           description: description,
           state: state,
           author_id: author_id,
-          assignee_id: assignee_id,
+          assignee_ids: Array(assignee_id),
           created_at: raw_data.created_at,
           updated_at: raw_data.updated_at
         }

lib/gitlab/google_code_import/importer.rb

@@ -92,13 +92,13 @@ module Gitlab
           end
 
           issue = Issue.create!(
-            iid:         raw_issue['id'],
-            project_id:  project.id,
-            title:       raw_issue['title'],
-            description: body,
-            author_id:   project.creator_id,
-            assignee_id: assignee_id,
-            state:       raw_issue['state'] == 'closed' ? 'closed' : 'opened'
+            iid:          raw_issue['id'],
+            project_id:   project.id,
+            title:        raw_issue['title'],
+            description:  body,
+            author_id:    project.creator_id,
+            assignee_ids: [assignee_id],
+            state:        raw_issue['state'] == 'closed' ? 'closed' : 'opened'
           )
 
           issue_labels = ::LabelsFinder.new(nil, project_id: project.id, title: labels).execute(skip_authorization: true)

spec/features/atom/dashboard_issues_spec.rb

@@ -41,7 +41,7 @@ describe "Dashboard Issues Feed", feature: true  do
 
           expect(entry).to be_present
           expect(entry).to have_selector('author email', text: issue2.author_public_email)
-          expect(entry).to have_selector('assignee email', text: issue2.assignee_public_email)
+          expect(entry).to have_selector('assignees email', text: issue2.assignees.first.public_email)
           expect(entry).not_to have_selector('labels')
           expect(entry).not_to have_selector('milestone')
           expect(entry).to have_selector('description', text: issue2.description)
@@ -64,7 +64,7 @@ describe "Dashboard Issues Feed", feature: true  do
 
           expect(entry).to be_present
           expect(entry).to have_selector('author email', text: issue1.author_public_email)
-          expect(entry).to have_selector('assignee email', text: issue1.assignee_public_email)
+          expect(entry).to have_selector('assignees email', text: issue1.assignees.first.public_email)
           expect(entry).to have_selector('labels label', text: label1.title)
           expect(entry).to have_selector('milestone', text: milestone1.title)
           expect(entry).not_to have_selector('description')

spec/features/issues/award_emoji_spec.rb

@@ -7,7 +7,7 @@ describe 'Awards Emoji', feature: true do
   let!(:user)      { create(:user) }
   let(:issue) do
     create(:issue,
-           assignees: [@user],
+           assignees: [user],
            project: project)
   end
 

spec/features/issues_spec.rb

@@ -62,7 +62,7 @@ describe 'Issues', feature: true do
         expect(page).to have_content 'No assignee - assign yourself'
       end
 
-      expect(issue.reload.assignee).to be_nil
+      expect(issue.reload.assignees).to be_empty
     end
   end
 
@@ -363,9 +363,9 @@ describe 'Issues', feature: true do
       let(:user2) { create(:user) }
 
       before do
-        foo.assignee = user2
+        foo.assignees << user2
         foo.save
-        bar.assignee = user2
+        bar.assignees << user2
         bar.save
       end
 
@@ -440,7 +440,7 @@ describe 'Issues', feature: true do
           expect(page).to have_content 'No assignee'
         end
 
-        expect(issue.reload.assignee).to be_nil
+        expect(issue.reload.assignees).to be_empty
       end
 
       it 'allows user to select an assignee', js: true do
@@ -498,7 +498,7 @@ describe 'Issues', feature: true do
         login_with guest
 
         visit namespace_project_issue_path(project.namespace, project, issue)
-        expect(page).to have_content issue.assignee.name
+        expect(page).to have_content issue.assignees.first.name
       end
     end
   end
@@ -590,7 +590,7 @@ describe 'Issues', feature: true do
       let(:user2) { create(:user) }
 
       before do
-        issue.assignee = user2
+        issue.assignees << user2
         issue.save
       end
     end

spec/fixtures/api/schemas/issue.json

@@ -40,21 +40,23 @@
         "additionalProperties": false
       }
     },
-    "assignee": {
-      "type": ["object", "null"],
-      "required": [
-        "id",
-        "name",
-        "username",
-        "avatar_url"
-      ],
-      "properties": {
-        "id": { "type": "integer" },
-        "name": { "type": "string" },
-        "username": { "type": "string" },
-        "avatar_url": { "type": "uri" }
-      },
-      "additionalProperties": false
+    "assignees": {
+      "type": "array",
+      "items": {
+        "type": ["object", "null"],
+        "required": [
+          "id",
+          "name",
+          "username",
+          "avatar_url"
+        ],
+        "properties": {
+          "id": { "type": "integer" },
+          "name": { "type": "string" },
+          "username": { "type": "string" },
+          "avatar_url": { "type": "uri" }
+        }
+      }
     },
     "subscribed": { "type": ["boolean", "null"] }
   },

spec/fixtures/api/schemas/public_api/v4/issues.json

@@ -33,17 +33,20 @@
         },
         "additionalProperties": false
       },
-      "assignee": {
-        "type": ["object", "null"],
-        "properties": {
-          "name": { "type": "string" },
-          "username": { "type": "string" },
-          "id": { "type": "integer" },
-          "state": { "type": "string" },
-          "avatar_url": { "type": "uri" },
-          "web_url": { "type": "uri" }
-        },
-        "additionalProperties": false
+      "assignees": {
+        "type": "array",
+        "items": {
+          "type": ["object", "null"],
+          "properties": {
+            "name": { "type": "string" },
+            "username": { "type": "string" },
+            "id": { "type": "integer" },
+            "state": { "type": "string" },
+            "avatar_url": { "type": "uri" },
+            "web_url": { "type": "uri" }
+          },
+          "additionalProperties": false
+        }
       },
       "author": {
         "type": "object",
@@ -68,7 +71,7 @@
     "required": [
       "id", "iid", "project_id", "title", "description",
       "state", "created_at", "updated_at", "labels",
-      "milestone", "assignee", "author", "user_notes_count",
+      "milestone", "assignees", "author", "user_notes_count",
       "upvotes", "downvotes", "due_date", "confidential",
       "web_url", "weight"
     ],

spec/lib/banzai/filter/redactor_filter_spec.rb

@@ -103,7 +103,7 @@ describe Banzai::Filter::RedactorFilter, lib: true do
       it 'allows references for assignee' do
         assignee = create(:user)
         project = create(:empty_project, :public)
-        issue = create(:issue, :confidential, project: project, assignee: assignee)
+        issue = create(:issue, :confidential, project: project, assignees: [assignee])
 
         link = reference_link(project: project.id, issue: issue.id, reference_type: 'issue')
         doc = filter(link, current_user: assignee)

spec/lib/gitlab/github_import/issue_formatter_spec.rb

@@ -43,7 +43,7 @@ describe Gitlab::GithubImport::IssueFormatter, lib: true do
           description: "*Created by: octocat*\n\nI'm having a problem with this.",
           state: 'opened',
           author_id: project.creator_id,
-          assignee_id: nil,
+          assignee_ids: [],
           created_at: created_at,
           updated_at: updated_at
         }
@@ -64,7 +64,7 @@ describe Gitlab::GithubImport::IssueFormatter, lib: true do
           description: "*Created by: octocat*\n\nI'm having a problem with this.",
           state: 'closed',
           author_id: project.creator_id,
-          assignee_id: nil,
+          assignee_ids: [],
           created_at: created_at,
           updated_at: updated_at
         }
@@ -77,19 +77,19 @@ describe Gitlab::GithubImport::IssueFormatter, lib: true do
       let(:raw_data) { double(base_data.merge(assignee: octocat)) }
 
       it 'returns nil as assignee_id when is not a GitLab user' do
-        expect(issue.attributes.fetch(:assignee_id)).to be_nil
+        expect(issue.attributes.fetch(:assignee_ids)).to be_empty
       end
 
       it 'returns GitLab user id associated with GitHub id as assignee_id' do
         gl_user = create(:omniauth_user, extern_uid: octocat.id, provider: 'github')
 
-        expect(issue.attributes.fetch(:assignee_id)).to eq gl_user.id
+        expect(issue.attributes.fetch(:assignee_ids)).to eq [gl_user.id]
       end
 
       it 'returns GitLab user id associated with GitHub email as assignee_id' do
         gl_user = create(:user, email: octocat.email)
 
-        expect(issue.attributes.fetch(:assignee_id)).to eq gl_user.id
+        expect(issue.attributes.fetch(:assignee_ids)).to eq [gl_user.id]
       end
     end
 

spec/lib/gitlab/google_code_import/importer_spec.rb

@@ -49,7 +49,7 @@ describe Gitlab::GoogleCodeImport::Importer, lib: true do
       expect(issue).not_to be_nil
       expect(issue.iid).to eq(169)
       expect(issue.author).to eq(project.creator)
-      expect(issue.assignee).to eq(mapped_user)
+      expect(issue.assignees).to eq([mapped_user])
       expect(issue.state).to eq("closed")
       expect(issue.label_names).to include("Priority: Medium")
       expect(issue.label_names).to include("Status: Fixed")

spec/lib/gitlab/import_export/all_models.yml

@@ -3,7 +3,7 @@ issues:
 - subscriptions
 - award_emoji
 - author
-- assignee
+- assignees
 - updated_by
 - milestone
 - notes
@@ -16,6 +16,7 @@ issues:
 - merge_requests_closing_issues
 - metrics
 - timelogs
+- issue_assignees
 events:
 - author
 - project

spec/models/concerns/elastic/issue_spec.rb

@@ -35,7 +35,9 @@ describe Issue, elastic: true do
 
     expected_hash = issue.attributes.extract!('id', 'iid', 'title', 'description', 'created_at',
                                                 'updated_at', 'state', 'project_id', 'author_id',
-                                                'assignee_id', 'confidential')
+                                                'confidential')
+
+    expected_hash['assignee_id'] = []
 
     expect(issue.as_indexed_json).to eq(expected_hash)
   end

spec/models/concerns/issuable_spec.rb

@@ -7,7 +7,6 @@ describe Issue, "Issuable" do
   describe "Associations" do
     it { is_expected.to belong_to(:project) }
     it { is_expected.to belong_to(:author) }
-    it { is_expected.to belong_to(:assignee) }
     it { is_expected.to have_many(:notes).dependent(:destroy) }
     it { is_expected.to have_many(:todos).dependent(:destroy) }
 
@@ -58,12 +57,12 @@ describe Issue, "Issuable" do
   end
 
   describe "before_save" do
-    describe "#update_cache_counts" do
+    describe "#update_cache_counts when an issue is reassigned" do
       context "when previous assignee exists" do
         before do
           assignee = create(:user)
           issue.project.team << [assignee, :developer]
-          issue.update(assignee: assignee)
+          issue.assignees << assignee
         end
 
         it "updates cache counts for new assignee" do
@@ -71,26 +70,65 @@ describe Issue, "Issuable" do
 
           expect(user).to receive(:update_cache_counts)
 
-          issue.update(assignee: user)
+          issue.assignees << user
         end
 
         it "updates cache counts for previous assignee" do
-          old_assignee = issue.assignee
+          old_assignee = issue.assignees.first
+
+          expect_any_instance_of(User).to receive(:update_cache_counts)
+
+          issue.assignees.destroy_all
+        end
+      end
+
+      context "when previous assignee does not exist" do
+        before{ issue.assignees = [] }
+
+        it "updates cache count for the new assignee" do
+          expect_any_instance_of(User).to receive(:update_cache_counts)
+
+          issue.assignees << user
+        end
+      end
+    end
+
+    describe "#update_cache_counts when a merge request is reassigned" do
+      let(:project) { create :project }
+      let(:merge_request) { create(:merge_request, source_project: project, target_project: project) }
+
+      context "when previous assignee exists" do
+        before do
+          assignee = create(:user)
+          project.team << [assignee, :developer]
+          merge_request.update(assignee: assignee)
+        end
+
+        it "updates cache counts for new assignee" do
+          user = create(:user)
+
+          expect(user).to receive(:update_cache_counts)
+
+          merge_request.update(assignee: user)
+        end
+
+        it "updates cache counts for previous assignee" do
+          old_assignee = merge_request.assignee
           allow(User).to receive(:find_by_id).with(old_assignee.id).and_return(old_assignee)
 
           expect(old_assignee).to receive(:update_cache_counts)
 
-          issue.update(assignee: nil)
+          merge_request.update(assignee: nil)
         end
       end
 
       context "when previous assignee does not exist" do
-        before{ issue.update(assignee: nil) }
+        before { merge_request.update(assignee: nil) }
 
         it "updates cache count for the new assignee" do
           expect_any_instance_of(User).to receive(:update_cache_counts)
 
-          issue.update(assignee: user)
+          merge_request.update(assignee: user)
         end
       end
     end
@@ -300,7 +338,20 @@ describe Issue, "Issuable" do
     end
 
     context "issue is assigned" do
-      before { issue.update_attribute(:assignee, user) }
+      before { issue.assignees << user }
+
+      it "returns correct hook data" do
+        expect(data[:assignees].first).to eq(user.hook_attrs)
+      end
+    end
+
+    context "merge_request is assigned" do
+      let(:merge_request) { create(:merge_request) }
+      let(:data) { merge_request.to_hook_data(user) }
+
+      before do
+        merge_request.update_attribute(:assignee, user)
+      end
 
       it "returns correct hook data" do
         expect(data[:object_attributes]['assignee_id']).to eq(user.id)
@@ -322,24 +373,6 @@ describe Issue, "Issuable" do
     include_examples 'deprecated repository hook data'
   end
 
-  describe '#card_attributes' do
-    it 'includes the author name' do
-      allow(issue).to receive(:author).and_return(double(name: 'Robert'))
-      allow(issue).to receive(:assignee).and_return(nil)
-
-      expect(issue.card_attributes).
-        to eq({ 'Author' => 'Robert', 'Assignee' => nil })
-    end
-
-    it 'includes the assignee name' do
-      allow(issue).to receive(:author).and_return(double(name: 'Robert'))
-      allow(issue).to receive(:assignee).and_return(double(name: 'Douwe'))
-
-      expect(issue.card_attributes).
-        to eq({ 'Author' => 'Robert', 'Assignee' => 'Douwe' })
-    end
-  end
-
   describe '#labels_array' do
     let(:project) { create(:empty_project) }
     let(:bug) { create(:label, project: project, title: 'bug') }

spec/models/issue_collection_spec.rb

@@ -28,7 +28,7 @@ describe IssueCollection do
       end
 
       it 'returns the issues the user is assigned to' do
-        issue1.assignee = user
+        issue1.assignees << user
 
         expect(collection.updatable_by_user(user)).to eq([issue1])
       end

spec/models/issue_spec.rb

@@ -3,6 +3,7 @@ require 'spec_helper'
 describe Issue, models: true do
   describe "Associations" do
     it { is_expected.to belong_to(:milestone) }
+    it { is_expected.to have_many(:assignees) }
   end
 
   describe 'modules' do
@@ -37,6 +38,24 @@ describe Issue, models: true do
     end
   end
 
+  describe '#card_attributes' do
+    it 'includes the author name' do
+      allow(subject).to receive(:author).and_return(double(name: 'Robert'))
+      allow(subject).to receive(:assignees).and_return([])
+
+      expect(subject.card_attributes).
+        to eq({ 'Author' => 'Robert', 'Assignee' => '' })
+    end
+
+    it 'includes the assignee name' do
+      allow(subject).to receive(:author).and_return(double(name: 'Robert'))
+      allow(subject).to receive(:assignees).and_return([double(name: 'Douwe')])
+
+      expect(subject.card_attributes).
+        to eq({ 'Author' => 'Robert', 'Assignee' => 'Douwe' })
+    end
+  end
+
   describe '#closed_at' do
     after do
       Timecop.return
@@ -153,25 +172,6 @@ describe Issue, models: true do
     end
   end
 
-  describe '#is_being_reassigned?' do
-    it 'returns true if the issue assignee has changed' do
-      subject.assignee = create(:user)
-      expect(subject.is_being_reassigned?).to be_truthy
-    end
-    it 'returns false if the issue assignee has not changed' do
-      expect(subject.is_being_reassigned?).to be_falsey
-    end
-  end
-
-  describe '#is_being_reassigned?' do
-    it 'returns issues assigned to user' do
-      user = create(:user)
-      create_list(:issue, 2, assignees: [user])
-
-      expect(Issue.open_for(user).count).to eq 2
-    end
-  end
-
   describe '#closed_by_merge_requests' do
     let(:project) { create(:project, :repository) }
     let(:issue) { create(:issue, project: project)}
@@ -404,7 +404,7 @@ describe Issue, models: true do
       expect(user1.assigned_open_issues_count).to eq(1)
       expect(user2.assigned_open_issues_count).to eq(0)
 
-      issue.assignee = user2
+      issue.assignees = [user2]
       issue.save
 
       expect(user1.assigned_open_issues_count).to eq(0)

spec/models/merge_request_spec.rb

@@ -9,6 +9,7 @@ describe MergeRequest, models: true 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(:merge_request_diffs).dependent(:destroy) }
     it { is_expected.to have_many(:approver_groups).dependent(:destroy) }
   end
@@ -87,8 +88,26 @@ describe MergeRequest, models: true do
     end
   end
 
+  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)
+
+      expect(subject.card_attributes).
+        to eq({ 'Author' => 'Robert', 'Assignee' => nil })
+    end
+
+    it 'includes the assignee name' do
+      allow(subject).to receive(:author).and_return(double(name: 'Robert'))
+      allow(subject).to receive(:assignee).and_return(double(name: 'Douwe'))
+
+      expect(subject.card_attributes).
+        to eq({ 'Author' => 'Robert', 'Assignee' => 'Douwe' })
+    end
+  end
+
   describe '#assignee_or_author?' do
-    let(:user) { build(:user) }
+    let(:user) { create(:user) }
 
     it 'returns true for a user that is assigned to a merge request' do
       subject.assignee = user
@@ -298,16 +317,6 @@ describe MergeRequest, models: true do
     end
   end
 
-  describe '#is_being_reassigned?' do
-    it 'returns true if the merge_request assignee has changed' do
-      subject.assignee = create(:user)
-      expect(subject.is_being_reassigned?).to be_truthy
-    end
-    it 'returns false if the merge request assignee has not changed' do
-      expect(subject.is_being_reassigned?).to be_falsey
-    end
-  end
-
   describe '#for_fork?' do
     it 'returns true if the merge request is for a fork' do
       subject.source_project = build_stubbed(:empty_project, namespace: create(:group))

spec/models/user_spec.rb

@@ -24,7 +24,6 @@ describe User, models: true do
     it { is_expected.to have_many(:recent_events).class_name('Event') }
     it { is_expected.to have_many(:issues).dependent(:restrict_with_exception) }
     it { is_expected.to have_many(:notes).dependent(:destroy) }
-    it { is_expected.to have_many(:assigned_issues).dependent(:nullify) }
     it { is_expected.to have_many(:merge_requests).dependent(:destroy) }
     it { is_expected.to have_many(:assigned_merge_requests).dependent(:nullify) }
     it { is_expected.to have_many(:identities).dependent(:destroy) }

spec/requests/api/issues_spec.rb

@@ -788,7 +788,7 @@ describe API::Issues, api: true  do
       expect(json_response['updated_at']).to be_present
       expect(json_response['labels']).to eq(issue.label_names)
       expect(json_response['milestone']).to be_a Hash
-      expect(json_response['assignee']).to be_a Hash
+      expect(json_response['assignees']).to be_a Array
       expect(json_response['author']).to be_a Hash
       expect(json_response['confidential']).to be_falsy
       expect(json_response['weight']).to be_nil

spec/services/issuable/bulk_update_service_spec.rb

@@ -4,11 +4,12 @@ describe Issuable::BulkUpdateService, services: true do
   let(:user)    { create(:user) }
   let(:project) { create(:empty_project, namespace: user.namespace) }
 
-  def bulk_update(issues, extra_params = {})
+  def bulk_update(issuables, extra_params = {})
     bulk_update_params = extra_params
-      .reverse_merge(issuable_ids: Array(issues).map(&:id).join(','))
+      .reverse_merge(issuable_ids: Array(issuables).map(&:id).join(','))
 
-    Issuable::BulkUpdateService.new(project, user, bulk_update_params).execute('issue')
+    type = Array(issuables).first.model_name.param_key
+    Issuable::BulkUpdateService.new(project, user, bulk_update_params).execute(type)
   end
 
   describe 'close issues' do
@@ -47,15 +48,15 @@ describe Issuable::BulkUpdateService, services: true do
     end
   end
 
-  describe 'updating assignee' do
-    let(:issue) { create(:issue, project: project, assignee: user) }
+  describe 'updating merge request assignee' do
+    let(:merge_request) { create(:merge_request, target_project: project, source_project: project, assignee: user) }
 
     context 'when the new assignee ID is a valid user' do
       it 'succeeds' do
         new_assignee = create(:user)
         project.team << [new_assignee, :developer]
 
-        result = bulk_update(issue, assignee_id: new_assignee.id)
+        result = bulk_update(merge_request, assignee_id: new_assignee.id)
 
         expect(result[:success]).to be_truthy
         expect(result[:count]).to eq(1)
@@ -65,22 +66,59 @@ describe Issuable::BulkUpdateService, services: true do
         assignee = create(:user)
         project.team << [assignee, :developer]
 
-        expect { bulk_update(issue, assignee_id: assignee.id) }
-          .to change { issue.reload.assignee }.from(user).to(assignee)
+        expect { bulk_update(merge_request, assignee_id: assignee.id) }
+          .to change { merge_request.reload.assignee }.from(user).to(assignee)
       end
     end
 
     context "when the new assignee ID is #{IssuableFinder::NONE}" do
       it "unassigns the issues" do
-        expect { bulk_update(issue, assignee_id: IssuableFinder::NONE) }
-          .to change { issue.reload.assignee }.to(nil)
+        expect { bulk_update(merge_request, assignee_id: IssuableFinder::NONE) }
+          .to change { merge_request.reload.assignee }.to(nil)
       end
     end
 
     context 'when the new assignee ID is not present' do
       it 'does not unassign' do
-        expect { bulk_update(issue, assignee_id: nil) }
-          .not_to change { issue.reload.assignee }
+        expect { bulk_update(merge_request, assignee_id: nil) }
+          .not_to change { merge_request.reload.assignee }
+      end
+    end
+  end
+
+  describe 'updating issue assignee' do
+    let(:issue) { create(:issue, project: project, assignees: [user]) }
+
+    context 'when the new assignee ID is a valid user' do
+      it 'succeeds' do
+        new_assignee = create(:user)
+        project.team << [new_assignee, :developer]
+
+        result = bulk_update(issue, assignee_ids: [new_assignee.id])
+
+        expect(result[:success]).to be_truthy
+        expect(result[:count]).to eq(1)
+      end
+
+      it 'updates the assignee to the use ID passed' do
+        assignee = create(:user)
+        project.team << [assignee, :developer]
+        expect { bulk_update(issue, assignee_ids: [assignee.id]) }
+          .to change { issue.reload.assignees.first }.from(user).to(assignee)
+      end
+    end
+
+    context "when the new assignee ID is #{IssuableFinder::NONE}" do
+      it "unassigns the issues" do
+        expect { bulk_update(issue, assignee_ids: [IssuableFinder::NONE.to_s]) }
+          .to change { issue.reload.assignees.count }.from(1).to(0)
+      end
+    end
+
+    context 'when the new assignee ID is not present' do
+      it 'does not unassign' do
+        expect { bulk_update(issue, assignee_ids: []) }
+          .not_to change{ issue.reload.assignees }
       end
     end
   end

spec/services/issues/create_service_spec.rb

@@ -6,10 +6,10 @@ describe Issues::CreateService, services: true do
 
   describe '#execute' do
     let(:issue) { described_class.new(project, user, opts).execute }
+    let(:assignee) { create(:user) }
+    let(:milestone) { create(:milestone, project: project) }
 
     context 'when params are valid' do
-      let(:assignee) { create(:user) }
-      let(:milestone) { create(:milestone, project: project) }
       let(:labels) { create_pair(:label, project: project) }
 
       before do
@@ -20,7 +20,7 @@ describe Issues::CreateService, services: true do
       let(:opts) do
         { title: 'Awesome issue',
           description: 'please fix',
-          assignee_ids: assignee.id.to_s,
+          assignee_ids: [assignee.id],
           label_ids: labels.map(&:id),
           milestone_id: milestone.id,
           due_date: Date.tomorrow }
@@ -37,7 +37,7 @@ describe Issues::CreateService, services: true do
 
       context 'when current user cannot admin issues in the project' do
         let(:guest) { create(:user) }
-        
+
         before do
           project.team << [guest, :guest]
         end
@@ -137,10 +137,83 @@ describe Issues::CreateService, services: true do
       end
     end
 
-    it_behaves_like 'issuable create service'
+    context 'issue create service' do
+      context 'assignees' do
+        before { project.team << [user, :master] }
+
+        it 'removes assignee when user id is invalid' do
+          opts = { title: 'Title', description: 'Description', assignee_ids: [-1] }
+
+          issue = described_class.new(project, user, opts).execute
+
+          expect(issue.assignees).to be_empty
+        end
+
+        it 'removes assignee when user id is 0' do
+          opts = { title: 'Title', description: 'Description',  assignee_ids: [0] }
+
+          issue = described_class.new(project, user, opts).execute
+
+          expect(issue.assignees).to be_empty
+        end
+
+        it 'saves assignee when user id is valid' do
+          project.team << [assignee, :master]
+          opts = { title: 'Title', description: 'Description', assignee_ids: [assignee.id] }
+
+          issue = described_class.new(project, user, opts).execute
+
+          expect(issue.assignees).to eq([assignee])
+        end
+
+        context "when issuable feature is private" do
+          before do
+            project.project_feature.update(issues_access_level: ProjectFeature::PRIVATE,
+                                           merge_requests_access_level: ProjectFeature::PRIVATE)
+          end
+
+          levels = [Gitlab::VisibilityLevel::INTERNAL, Gitlab::VisibilityLevel::PUBLIC]
+
+          levels.each do |level|
+            it "removes not authorized assignee when project is #{Gitlab::VisibilityLevel.level_name(level)}" do
+              project.update(visibility_level: level)
+              opts = { title: 'Title', description: 'Description', assignee_ids: [assignee.id] }
+
+              issue = described_class.new(project, user, opts).execute
+
+              expect(issue.assignees).to be_empty
+            end
+          end
+        end
+      end
+    end
 
     it_behaves_like 'new issuable record that supports slash commands'
 
+    context 'Slash commands' do
+      context 'with assignee and milestone in params and command' do
+        let(:opts) do
+          {
+            assignee_ids: [create(:user).id],
+            milestone_id: 1,
+            title: 'Title',
+            description: %(/assign @#{assignee.username}\n/milestone %"#{milestone.name}")
+          }
+        end
+
+        before do
+          project.team << [user, :master]
+          project.team << [assignee, :master]
+        end
+
+        it 'assigns and sets milestone to issuable from command' do
+          expect(issue).to be_persisted
+          expect(issue.assignees).to eq([assignee])
+          expect(issue.milestone).to eq(milestone)
+        end
+      end
+    end
+
     context 'resolving discussions' do
       let(:discussion) { Discussion.for_diff_notes([create(:diff_note_on_merge_request)]).first }
       let(:merge_request) { discussion.noteable }

spec/services/issues/update_service_spec.rb

@@ -162,7 +162,7 @@ describe Issues::UpdateService, services: true do
       it 'does not update assignee_id with unauthorized users' do
         project.update(visibility_level: Gitlab::VisibilityLevel::PUBLIC)
         update_issue(confidential: true)
-        non_member        = create(:user)
+        non_member = create(:user)
         original_assignees = issue.assignees
 
         update_issue(assignee_ids: [non_member.id])

spec/services/merge_requests/create_service_spec.rb

@@ -84,7 +84,87 @@ describe MergeRequests::CreateService, services: true do
       end
     end
 
-    it_behaves_like 'issuable create service'
+    context 'Slash commands' do
+      context 'with assignee and milestone in params and command' do
+        let(:merge_request) { described_class.new(project, user, opts).execute }
+        let(:milestone) { create(:milestone, project: project) }
+
+        let(:opts) do
+          {
+            assignee_id: create(:user).id,
+            milestone_id: 1,
+            title: 'Title',
+            description: %(/assign @#{assignee.username}\n/milestone %"#{milestone.name}"),
+            source_branch: 'feature',
+            target_branch: 'master'
+          }
+        end
+
+        before do
+          project.team << [user, :master]
+          project.team << [assignee, :master]
+        end
+
+        it 'assigns and sets milestone to issuable from command' do
+          expect(merge_request).to be_persisted
+          expect(merge_request.assignee).to eq(assignee)
+          expect(merge_request.milestone).to eq(milestone)
+        end
+      end
+    end
+
+    context 'merge request create service' do
+      context 'asssignee_id' do
+        let(:assignee) { create(:user) }
+
+        before { project.team << [user, :master] }
+
+        it 'removes assignee_id when user id is invalid' do
+          opts = { title: 'Title', description: 'Description', assignee_id: -1 }
+
+          merge_request = described_class.new(project, user, opts).execute
+
+          expect(merge_request.assignee_id).to be_nil
+        end
+
+        it 'removes assignee_id when user id is 0' do
+          opts = { title: 'Title', description: 'Description',  assignee_id: 0 }
+
+          merge_request = described_class.new(project, user, opts).execute
+
+          expect(merge_request.assignee_id).to be_nil
+        end
+
+        it 'saves assignee when user id is valid' do
+          project.team << [assignee, :master]
+          opts = { title: 'Title', description: 'Description', assignee_id: assignee.id }
+
+          merge_request = described_class.new(project, user, opts).execute
+
+          expect(merge_request.assignee).to eq(assignee)
+        end
+
+        context "when issuable feature is private" do
+          before do
+            project.project_feature.update(issues_access_level: ProjectFeature::PRIVATE,
+                                           merge_requests_access_level: ProjectFeature::PRIVATE)
+          end
+
+          levels = [Gitlab::VisibilityLevel::INTERNAL, Gitlab::VisibilityLevel::PUBLIC]
+
+          levels.each do |level|
+            it "removes not authorized assignee when project is #{Gitlab::VisibilityLevel.level_name(level)}" do
+              project.update(visibility_level: level)
+              opts = { title: 'Title', description: 'Description', assignee_id: assignee.id }
+
+              merge_request = described_class.new(project, user, opts).execute
+
+              expect(merge_request.assignee_id).to be_nil
+            end
+          end
+        end
+      end
+    end
 
     context 'while saving references to issues that the created merge request closes' do
       let(:first_issue) { create(:issue, project: project) }

spec/services/notes/slash_commands_service_spec.rb

@@ -66,7 +66,7 @@ describe Notes::SlashCommandsService, services: true do
           expect(content).to eq ''
           expect(note.noteable).to be_closed
           expect(note.noteable.labels).to match_array(labels)
-          expect(note.noteable.assignee).to eq(assignee)
+          expect(note.noteable.assignees).to eq([assignee])
           expect(note.noteable.milestone).to eq(milestone)
         end
       end
@@ -113,7 +113,7 @@ describe Notes::SlashCommandsService, services: true do
           expect(content).to eq "HELLO\nWORLD"
           expect(note.noteable).to be_closed
           expect(note.noteable.labels).to match_array(labels)
-          expect(note.noteable.assignee).to eq(assignee)
+          expect(note.noteable.assignees).to eq([assignee])
           expect(note.noteable.milestone).to eq(milestone)
         end
       end

spec/services/notification_service_spec.rb

@@ -569,7 +569,7 @@ describe NotificationService, services: true do
       end
 
       it 'emails previous assignee even if he has the "on mention" notif level' do
-        issue.assignees =  [@u_mentioned]
+        issue.assignees = [@u_mentioned]
         notification.reassigned_issue(issue, @u_disabled, [@u_watcher])
 
         should_email(@u_mentioned)

spec/services/slash_commands/interpret_service_spec.rb

@@ -42,23 +42,6 @@ describe SlashCommands::InterpretService, services: true do
       end
     end
 
-    shared_examples 'assign command' do
-      it 'fetches assignee and populates assignee_id if content contains /assign' do
-        _, updates = service.execute(content, issuable)
-
-        expect(updates).to eq(assignee_id: developer.id)
-      end
-    end
-
-    shared_examples 'unassign command' do
-      it 'populates assignee_id: nil if content contains /unassign' do
-        issuable.update(assignee_id: developer.id)
-        _, updates = service.execute(content, issuable)
-
-        expect(updates).to eq(assignee_id: nil)
-      end
-    end
-
     shared_examples 'milestone command' do
       it 'fetches milestone and populates milestone_id if content contains /milestone' do
         milestone # populate the milestone
@@ -385,14 +368,24 @@ describe SlashCommands::InterpretService, services: true do
       let(:issuable) { issue }
     end
 
-    it_behaves_like 'assign command' do
+    context 'assign command' do
       let(:content) { "/assign @#{developer.username}" }
-      let(:issuable) { issue }
-    end
 
-    it_behaves_like 'assign command' do
-      let(:content) { "/assign @#{developer.username}" }
-      let(:issuable) { merge_request }
+      context 'Issue' do
+        it 'fetches assignee and populates assignee_id if content contains /assign' do
+          _, updates = service.execute(content, issue)
+
+          expect(updates).to eq(assignee_ids: [developer.id])
+        end
+      end
+
+      context 'Merge Request' do
+        it 'fetches assignee and populates assignee_id if content contains /assign' do
+          _, updates = service.execute(content, merge_request)
+
+          expect(updates).to eq(assignee_id: developer.id)
+        end
+      end
     end
 
     it_behaves_like 'empty command' do
@@ -405,14 +398,26 @@ describe SlashCommands::InterpretService, services: true do
       let(:issuable) { issue }
     end
 
-    it_behaves_like 'unassign command' do
+    context 'unassign command' do
       let(:content) { '/unassign' }
-      let(:issuable) { issue }
-    end
 
-    it_behaves_like 'unassign command' do
-      let(:content) { '/unassign' }
-      let(:issuable) { merge_request }
+      context 'Issue' do
+        it 'populates assignee_ids: [] if content contains /unassign' do
+          issue.update(assignee_ids: [developer.id])
+          _, updates = service.execute(content, issue)
+
+          expect(updates).to eq(assignee_ids: [])
+        end
+      end
+
+      context 'Merge Request' do
+        it 'populates assignee_id: nil if content contains /unassign' do
+          merge_request.update(assignee_id: developer.id)
+          _, updates = service.execute(content, merge_request)
+
+          expect(updates).to eq(assignee_id: nil)
+        end
+      end
     end
 
     it_behaves_like 'milestone command' do

spec/services/system_note_service_spec.rb

@@ -6,6 +6,7 @@ describe SystemNoteService, services: true do
   let(:project)  { create(:project) }
   let(:author)   { create(:user) }
   let(:noteable) { create(:issue, project: project) }
+  let(:issue)    { noteable }
 
   shared_examples_for 'a system note' do
     it 'is valid' do
@@ -133,6 +134,50 @@ describe SystemNoteService, services: true do
     end
   end
 
+  describe '.change_issue_assignees' do
+    subject { described_class.change_issue_assignees(noteable, project, author, [assignee]) }
+
+    let(:assignee) { create(:user) }
+    let(:assignee1) { create(:user) }
+    let(:assignee2) { create(:user) }
+    let(:assignee3) { create(:user) }
+
+    it_behaves_like 'a system note'
+
+    def build_note(old_assignees, new_assignees)
+      issue.assignees = new_assignees
+      described_class.change_issue_assignees(issue, project, author, old_assignees).note
+    end
+
+    it 'builds a correct phrase when an assignee is added to a non-assigned issue' do
+      expect(build_note([], [assignee1])).to eq "assigned to @#{assignee1.username}"
+    end
+
+    it 'builds a correct phrase when assignee removed' do
+      expect(build_note([assignee1], [])).to eq 'removed all assignees'
+    end
+
+    it 'builds a correct phrase when assignees changed' do
+      expect(build_note([assignee1], [assignee2])).to eq \
+        "assigned to @#{assignee2.username} and unassigned @#{assignee1.username}"
+    end
+
+    it 'builds a correct phrase when three assignees removed and one added' do
+      expect(build_note([assignee, assignee1, assignee2], [assignee3])).to eq \
+        "assigned to @#{assignee3.username} and unassigned @#{assignee.username}, @#{assignee1.username}, and @#{assignee2.username}"
+    end
+
+    it 'builds a correct phrase when one assignee changed from a set' do
+      expect(build_note([assignee, assignee1], [assignee, assignee2])).to eq \
+        "assigned to @#{assignee2.username} and unassigned @#{assignee1.username}"
+    end
+
+    it 'builds a correct phrase when one assignee removed from a set' do
+      expect(build_note([assignee, assignee1, assignee2], [assignee, assignee1])).to eq \
+        "unassigned @#{assignee2.username}"
+    end
+  end
+
   describe '.change_label' do
     subject { described_class.change_label(noteable, project, author, added, removed) }
 

spec/services/todo_service_spec.rb

@@ -240,20 +240,20 @@ describe TodoService, services: true do
 
     describe '#reassigned_issue' do
       it 'creates a pending todo for new assignee' do
-        unassigned_issue.update_attribute(:assignee, john_doe)
+        unassigned_issue.assignees << john_doe
         service.reassigned_issue(unassigned_issue, author)
 
         should_create_todo(user: john_doe, target: unassigned_issue, action: Todo::ASSIGNED)
       end
 
       it 'does not create a todo if unassigned' do
-        issue.update_attribute(:assignee, nil)
+        issue.assignees.destroy_all
 
         should_not_create_any_todo { service.reassigned_issue(issue, author) }
       end
 
       it 'creates a todo if new assignee is the current user' do
-        unassigned_issue.update_attribute(:assignee, john_doe)
+        unassigned_issue.assignees << john_doe
         service.reassigned_issue(unassigned_issue, john_doe)
 
         should_create_todo(user: john_doe, target: unassigned_issue, author: john_doe, action: Todo::ASSIGNED)

spec/support/services/issuable_create_service_shared_examples.rb

-shared_examples 'issuable create service' do
-  context 'asssignee_id' do
-    let(:assignee) { create(:user) }
-
-    before { project.team << [user, :master] }
-
-    it 'removes assignee_id when user id is invalid' do
-      opts = { title: 'Title', description: 'Description', assignee_id: -1 }
-
-      issuable = described_class.new(project, user, opts).execute
-
-      expect(issuable.assignee_id).to be_nil
-    end
-
-    it 'removes assignee_id when user id is 0' do
-      opts = { title: 'Title', description: 'Description',  assignee_id: 0 }
-
-      issuable = described_class.new(project, user, opts).execute
-
-      expect(issuable.assignee_id).to be_nil
-    end
-
-    it 'saves assignee when user id is valid' do
-      project.team << [assignee, :master]
-      opts = { title: 'Title', description: 'Description', assignee_id: assignee.id }
-
-      issuable = described_class.new(project, user, opts).execute
-
-      expect(issuable.assignee_id).to eq(assignee.id)
-    end
-
-    context "when issuable feature is private" do
-      before do
-        project.project_feature.update(issues_access_level: ProjectFeature::PRIVATE,
-                                       merge_requests_access_level: ProjectFeature::PRIVATE)
-      end
-
-      levels = [Gitlab::VisibilityLevel::INTERNAL, Gitlab::VisibilityLevel::PUBLIC]
-
-      levels.each do |level|
-        it "removes not authorized assignee when project is #{Gitlab::VisibilityLevel.level_name(level)}" do
-          project.update(visibility_level: level)
-          opts = { title: 'Title', description: 'Description', assignee_id: assignee.id }
-
-          issuable = described_class.new(project, user, opts).execute
-
-          expect(issuable.assignee_id).to be_nil
-        end
-      end
-    end
-  end
-end

spec/support/services/issuable_create_service_slash_commands_shared_examples.rb

@@ -49,23 +49,7 @@ shared_examples 'new issuable record that supports slash commands' do
 
     it 'assigns and sets milestone to issuable' do
       expect(issuable).to be_persisted
-      expect(issuable.assignee).to eq(assignee)
-      expect(issuable.milestone).to eq(milestone)
-    end
-  end
-
-  context 'with assignee and milestone in params and command' do
-    let(:example_params) do
-      {
-        assignee: create(:user),
-        milestone_id: 1,
-        description: %(/assign @#{assignee.username}\n/milestone %"#{milestone.name}")
-      }
-    end
-
-    it 'assigns and sets milestone to issuable from command' do
-      expect(issuable).to be_persisted
-      expect(issuable.assignee).to eq(assignee)
+      expect(issuable.assignees).to eq([assignee])
       expect(issuable.milestone).to eq(milestone)
     end
   end