Merge branch '6470-milestone-dates-integrated-into-epics' into 'master'

Add date fields to Epic to enable dates to source from milestones

Closes #6470

See merge request gitlab-org/gitlab-ee!6448

app/services/issues/update_service.rb

@@ -2,6 +2,7 @@
 
 module Issues
   class UpdateService < Issues::BaseService
+    prepend EE::Issues::UpdateService
     include SpamCheckService
 
     def execute(issue)

app/services/milestones/update_service.rb

@@ -2,6 +2,8 @@
 
 module Milestones
   class UpdateService < Milestones::BaseService
+    prepend EE::Milestones::UpdateService
+
     def execute(milestone)
       state = params[:state_event]
 

db/schema.rb

@@ -960,6 +960,12 @@ ActiveRecord::Schema.define(version: 20180803001726) do
     t.string "title_html", null: false
     t.text "description"
     t.text "description_html"
+    t.integer "start_date_sourcing_milestone_id"
+    t.integer "due_date_sourcing_milestone_id"
+    t.date "start_date_fixed"
+    t.date "due_date_fixed"
+    t.boolean "start_date_is_fixed"
+    t.boolean "due_date_is_fixed"
   end
 
   add_index "epics", ["assignee_id"], name: "index_epics_on_assignee_id", using: :btree

doc/api/epics.md

@@ -10,6 +10,14 @@ If epics feature is not available a `403` status code will be returned.
 
 The [epic issues API](epic_issues.md) allows you to interact with issues associated with an epic.
 
+# Milestone dates integration
+
+> [Introduced][ee-6448] in GitLab 11.2.
+
+Since start date and due date can be dynamically sourced from related issue milestones, when user has edit permission, additional fields will be shown. These include two boolean fields `start_date_is_fixed` and `due_date_is_fixed`, and four date fields `start_date_fixed`, `start_date_from_milestones`, `due_date_fixed` and `due_date_from_milestones`.
+
+`end_date` has been deprecated in favor of `due_date`.
+
 ## List epics for a group
 
 Gets all epics of the requested group and its subgroups.
@@ -51,11 +59,18 @@ Example response:
     "avatar_url": "http://www.gravatar.com/avatar/018729e129a6f31c80a6327a30196823?s=80&d=identicon",
     "web_url": "http://localhost:3001/kam"
   },
-  "labels": [],
   "start_date": null,
-  "end_date": null,
-  "created_at": "2018-01-21T06:21:13.165Z",
-  "updated_at": "2018-01-22T12:41:41.166Z"
+  "start_date_is_fixed": false,
+  "start_date_fixed": null,
+  "start_date_from_milestones": null,
+  "end_date": "2018-07-31",
+  "due_date": "2018-07-31",
+  "due_date_is_fixed": false,
+  "due_date_fixed": null,
+  "due_date_from_milestones": "2018-07-31",
+  "created_at": "2018-07-17T13:36:22.770Z",
+  "updated_at": "2018-07-18T12:22:05.239Z",
+  "labels": []
   }
 ]
 ```
@@ -95,9 +110,17 @@ Example response:
     "web_url": "http://localhost:3001/arnita"
   },
   "start_date": null,
-  "end_date": null,
-  "created_at": "2018-01-21T06:21:13.165Z",
-  "updated_at": "2018-01-22T12:41:41.166Z"
+  "start_date_is_fixed": false,
+  "start_date_fixed": null,
+  "start_date_from_milestones": null,
+  "end_date": "2018-07-31",
+  "due_date": "2018-07-31",
+  "due_date_is_fixed": false,
+  "due_date_fixed": null,
+  "due_date_from_milestones": "2018-07-31",
+  "created_at": "2018-07-17T13:36:22.770Z",
+  "updated_at": "2018-07-18T12:22:05.239Z",
+  "labels": []
 }
 ```
 
@@ -139,11 +162,18 @@ Example response:
     "id" : 18,
     "username" : "eileen.lowe"
   },
-  "labels": [],
   "start_date": null,
-  "end_date": null,
-  "created_at": "2018-01-21T06:21:13.165Z",
-  "updated_at": "2018-01-22T12:41:41.166Z"
+  "start_date_is_fixed": false,
+  "start_date_fixed": null,
+  "start_date_from_milestones": null,
+  "end_date": "2018-07-31",
+  "due_date": "2018-07-31",
+  "due_date_is_fixed": false,
+  "due_date_fixed": null,
+  "due_date_from_milestones": "2018-07-31",
+  "created_at": "2018-07-17T13:36:22.770Z",
+  "updated_at": "2018-07-18T12:22:05.239Z",
+  "labels": []
 }
 ```
 
@@ -151,6 +181,8 @@ Example response:
 
 Updates an epic
 
+Note that after 11.2, `start_date` and `end_date` should no longer be updated directly, as they are now composite fields. User can configure the `_is_fixed` and `_fixed` fields instead.
+
 ```
 PUT /groups/:id/epics/:epic_iid
 ```
@@ -162,8 +194,10 @@ PUT /groups/:id/epics/:epic_iid
 | `title`             | string           | no         | The title of an epic |
 | `description`       | string           | no         | The description of an epic  |
 | `labels`            | string           | no         | The comma separated list of labels |
-| `start_date`        | string           | no         | The start date of an epic  |
-| `end_date`          | string.          | no         | The end date of an epic |
+| `start_date_is_fixed` | boolean        | no         | Whether start date should be sourced from `start_date_fixed` |
+| `start_date_fixed`  | string           | no         | The fixed start date of an epic  |
+| `due_date_is_fixed` | boolean          | no         | Whether due date should be sourced from `due_date_fixed` |
+| `due_date_fixed`    | string           | no         | The fixed due date of an epic |
 
 ```bash
 curl --header PUT "PRIVATE-TOKEN: 9koXpg98eAheJpvBs5tK" https://gitlab.example.com/api/v4/groups/1/epics/5?title=New%20Title
@@ -186,11 +220,18 @@ Example response:
     "id" : 18,
     "username" : "eileen.lowe"
   },
-  "labels": [],
   "start_date": null,
-  "end_date": null,
-  "created_at": "2018-01-21T06:21:13.165Z",
-  "updated_at": "2018-01-22T12:41:41.166Z"
+  "start_date_is_fixed": false,
+  "start_date_fixed": null,
+  "start_date_from_milestones": null,
+  "end_date": "2018-07-31",
+  "due_date": "2018-07-31",
+  "due_date_is_fixed": false,
+  "due_date_fixed": null,
+  "due_date_from_milestones": "2018-07-31",
+  "created_at": "2018-07-17T13:36:22.770Z",
+  "updated_at": "2018-07-18T12:22:05.239Z",
+  "labels": []
 }
 ```
 
@@ -278,3 +319,5 @@ Example response:
   "created_at": "2016-07-01T11:09:13.992Z"
 }
 ```
+
+[ee-6448]: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/6448

ee/app/controllers/groups/epics_controller.rb

@@ -66,8 +66,10 @@ class Groups::EpicsController < Groups::ApplicationController
     [
       :title,
       :description,
-      :start_date,
-      :end_date,
+      :start_date_fixed,
+      :start_date_is_fixed,
+      :due_date_fixed,
+      :due_date_is_fixed,
       label_ids: []
     ]
   end

ee/app/finders/epics/date_sourcing_milestones_finder.rb

+# frozen_string_literal: true
+
+module Epics
+  class DateSourcingMilestonesFinder
+    include Gitlab::Utils::StrongMemoize
+
+    FIELDS = [:id, :start_date, :due_date].freeze
+    ID_INDEX = FIELDS.index(:id)
+    START_DATE_INDEX = FIELDS.index(:start_date)
+    DUE_DATE_INDEX = FIELDS.index(:due_date)
+
+    def initialize(epic_id)
+      @epic_id = epic_id
+    end
+
+    def execute
+      strong_memoize(:execute) do
+        Milestone.joins(issues: :epic_issue).where(epic_issues: { epic_id: epic_id }).joins(
+          <<~SQL
+            INNER JOIN (
+              SELECT MIN(milestones.start_date) AS start_date, MAX(milestones.due_date) AS due_date
+              FROM milestones
+              INNER JOIN issues ON issues.milestone_id = milestones.id
+              INNER JOIN epic_issues ON epic_issues.issue_id = issues.id
+              WHERE epic_issues.epic_id = #{epic_id}
+            ) inner_results ON (inner_results.start_date = milestones.start_date OR inner_results.due_date = milestones.due_date)
+          SQL
+        ).pluck(*FIELDS)
+      end
+    end
+
+    def start_date
+      start_date_sourcing_milestone&.slice(START_DATE_INDEX)
+    end
+
+    def start_date_sourcing_milestone_id
+      start_date_sourcing_milestone&.slice(ID_INDEX)
+    end
+
+    def due_date
+      due_date_sourcing_milestone&.slice(DUE_DATE_INDEX)
+    end
+
+    def due_date_sourcing_milestone_id
+      due_date_sourcing_milestone&.slice(ID_INDEX)
+    end
+
+    private
+
+    attr_reader :epic_id
+
+    def start_date_sourcing_milestone
+      @start_date_sourcing_milestone ||= execute
+        .reject { |row| row[START_DATE_INDEX].nil? }
+        .min_by { |row| row[START_DATE_INDEX] }
+    end
+
+    def due_date_sourcing_milestone
+      @due_date_sourcing_milestone ||= execute
+        .reject { |row| row[DUE_DATE_INDEX].nil? }
+        .max_by { |row| row[DUE_DATE_INDEX] }
+    end
+  end
+end

ee/app/helpers/epics_helper.rb

@@ -16,11 +16,25 @@ module EpicsHelper
       todo_exists: todo.present?,
       todo_path: group_todos_path(group),
       start_date: epic.start_date,
+      due_date: epic.due_date,
       end_date: epic.end_date
     }
 
     epic_meta[:todo_delete_path] = dashboard_todo_path(todo) if todo.present?
 
+    if Ability.allowed?(current_user, :update_epic, epic.group)
+      epic_meta.merge!(
+        start_date_fixed: epic.start_date_fixed,
+        start_date_is_fixed: epic.start_date_is_fixed?,
+        start_date_from_milestones: epic.start_date_from_milestones,
+        start_date_sourcing_milestone_title: epic.start_date_sourcing_milestone&.title,
+        due_date_fixed: epic.due_date_fixed,
+        due_date_is_fixed: epic.due_date_is_fixed?,
+        due_date_from_milestones: epic.due_date_from_milestones,
+        due_date_sourcing_milestone_title: epic.due_date_sourcing_milestone&.title
+      )
+    end
+
     participants = UserSerializer.new.represent(epic.participants)
     initial = opts[:initial].merge(labels: epic.labels,
                                    participants: participants,

ee/app/models/ee/epic.rb

@@ -13,10 +13,13 @@ module EE
 
       belongs_to :assignee, class_name: "User"
       belongs_to :group
+      belongs_to :start_date_sourcing_milestone, class_name: 'Milestone'
+      belongs_to :due_date_sourcing_milestone, class_name: 'Milestone'
 
       has_internal_id :iid, scope: :group, init: ->(s) { s&.group&.epics&.maximum(:iid) }
 
       has_many :epic_issues
+      has_many :issues, through: :epic_issues
 
       validates :group, presence: true
 
@@ -78,6 +81,36 @@ module EE
       def parent_class
         ::Group
       end
+
+      def update_start_and_due_dates(epics)
+        groups = epics.includes(:issues).group_by do |epic|
+          milestone_ids = epic.issues.map(&:milestone_id)
+          milestone_ids.compact!
+          milestone_ids.uniq!
+          milestone_ids
+        end
+
+        groups.each do |milestone_ids, epics|
+          next if milestone_ids.empty?
+
+          results = Epics::DateSourcingMilestonesFinder.new(epics.first.id)
+
+          self.where(id: epics.map(&:id)).update_all(
+            [
+              %{
+                start_date = CASE WHEN start_date_is_fixed = true THEN start_date ELSE ? END,
+                start_date_sourcing_milestone_id = ?,
+                end_date = CASE WHEN due_date_is_fixed = true THEN end_date ELSE ? END,
+                due_date_sourcing_milestone_id = ?
+              },
+              results.start_date,
+              results.start_date_sourcing_milestone_id,
+              results.due_date,
+              results.due_date_sourcing_milestone_id
+            ]
+          )
+        end
+      end
     end
 
     def assignees
@@ -109,6 +142,25 @@ module EE
     # Needed to use EntityDateHelper#remaining_days_in_words
     alias_attribute(:due_date, :end_date)
 
+    def update_start_and_due_dates
+      results = Epics::DateSourcingMilestonesFinder.new(id)
+
+      self.start_date = start_date_is_fixed? ? start_date_fixed : results.start_date
+      self.start_date_sourcing_milestone_id = results.start_date_sourcing_milestone_id
+      self.due_date = due_date_is_fixed? ? due_date_fixed : results.due_date
+      self.due_date_sourcing_milestone_id = results.due_date_sourcing_milestone_id
+
+      save if changed?
+    end
+
+    def start_date_from_milestones
+      start_date_is_fixed? ? start_date_sourcing_milestone&.start_date : start_date
+    end
+
+    def due_date_from_milestones
+      due_date_is_fixed? ? due_date_sourcing_milestone&.due_date : due_date
+    end
+
     def to_reference(from = nil, full: false)
       reference = "#{self.class.reference_prefix}#{iid}"
 
@@ -125,7 +177,7 @@ module EE
     def update_project_counter_caches
     end
 
-    def issues(current_user)
+    def issues_readable_by(current_user)
       related_issues = ::Issue.select('issues.*, epic_issues.id as epic_issue_id, epic_issues.relative_position')
         .joins(:epic_issue)
         .where("epic_issues.epic_id = #{id}")

ee/app/serializers/epic_entity.rb

@@ -6,8 +6,15 @@ class EpicEntity < IssuableEntity
   expose :group_full_name do |epic|
     epic.group.full_name
   end
+
   expose :start_date
-  expose :end_date
+  expose :start_date_is_fixed?, as: :start_date_is_fixed
+  expose :start_date_fixed, :start_date_from_milestones
+  expose :end_date # @deprecated
+  expose :end_date, as: :due_date
+  expose :due_date_is_fixed?, as: :due_date_is_fixed
+  expose :due_date_fixed, :due_date_from_milestones
+
   expose :web_url do |epic|
     group_epic_path(epic.group, epic)
   end

ee/app/services/ee/issues/update_service.rb

+# frozen_string_literal: true
+
+module EE
+  module Issues
+    module UpdateService
+      extend ::Gitlab::Utils::Override
+
+      override :execute
+      def execute(issue)
+        result = super
+
+        if issue.previous_changes.include?(:milestone_id) && issue.epic
+          issue.epic.update_start_and_due_dates
+        end
+
+        result
+      end
+    end
+  end
+end

ee/app/services/ee/milestones/update_service.rb

+# frozen_string_literal: true
+
+module EE
+  module Milestones
+    module UpdateService
+      extend ::Gitlab::Utils::Override
+
+      override :execute
+      def execute(milestone)
+        super
+
+        if dates_changed?(milestone)
+          ::Epic.update_start_and_due_dates(
+            ::Epic.joins(:issues).where(issues: { milestone_id: milestone.id })
+          )
+        end
+
+        milestone
+      end
+
+      private
+
+      def dates_changed?(milestone)
+        changes = milestone.previous_changes
+        changes.include?(:start_date) || changes.include?(:due_date)
+      end
+    end
+  end
+end

ee/app/services/epic_issues/create_service.rb

 module EpicIssues
   class CreateService < IssuableLinks::CreateService
+    def execute
+      result = super
+      issuable.update_start_and_due_dates
+      result
+    end
+
     private
 
     def relate_issues(referenced_issue)

ee/app/services/epic_issues/destroy_service.rb

 module EpicIssues
   class DestroyService < IssuableLinks::DestroyService
+    def execute
+      result = super
+      link.epic.update_start_and_due_dates
+      result
+    end
+
     private
 
     def source

ee/app/services/epic_issues/list_service.rb

@@ -5,7 +5,7 @@ module EpicIssues
     def issues
       return [] unless issuable&.group&.feature_available?(:epics)
 
-      issuable.issues(current_user)
+      issuable.issues_readable_by(current_user)
     end
 
     def relation_path(issue)

ee/app/services/epics/update_service.rb

 module Epics
   class UpdateService < Epics::BaseService
+    EPIC_DATE_FIELDS = %I[
+      start_date_fixed
+      start_date_is_fixed
+      due_date_fixed
+      due_date_is_fixed
+    ].freeze
+
     def execute(epic)
+      # start_date and end_date columns are no longer writable by users because those
+      # are composite fields managed by the system.
+      params.except!(:start_date, :end_date)
+
       update(epic)
 
+      epic.update_start_and_due_dates if have_epic_dates_changed?(epic)
+
       epic
     end
 
@@ -17,5 +30,11 @@ module Epics
 
       todo_service.update_epic(epic, current_user, old_mentioned_users)
     end
+
+    private
+
+    def have_epic_dates_changed?(epic)
+      (epic.previous_changes.keys.map(&:to_sym) & EPIC_DATE_FIELDS).present?
+    end
   end
 end

ee/changelogs/unreleased/6470-milestone-dates-integrated-into-epics.yml

+---
+title: Allow epic start/due dates to be sourceable from issue milestones
+merge_request: 6470
+author:
+type: added

ee/db/migrate/20180711014025_add_date_columns_to_epics.rb

+# frozen_string_literal: true
+
+class AddDateColumnsToEpics < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def change
+    change_table :epics do |t|
+      t.references :start_date_sourcing_milestone
+      t.references :due_date_sourcing_milestone
+      t.date :start_date_fixed
+      t.date :due_date_fixed
+      t.boolean :start_date_is_fixed
+      t.boolean :due_date_is_fixed
+    end
+  end
+end

ee/db/migrate/20180711014026_update_date_columns_on_epics.rb

+# frozen_string_literal: true
+
+class UpdateDateColumnsOnEpics < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  disable_ddl_transaction!
+
+  class Epic < ActiveRecord::Base
+    self.table_name = 'epics'
+    include EachBatch
+  end
+
+  def up
+    Epic.where.not(start_date: nil).each_batch do |batch|
+      batch.update_all('start_date_is_fixed = true, start_date_fixed = start_date')
+    end
+
+    Epic.where.not(end_date: nil).each_batch do |batch|
+      batch.update_all('due_date_is_fixed = true, due_date_fixed = end_date')
+    end
+  end
+
+  def down
+    # NOOP
+  end
+end

ee/db/post_migrate/20180713171825_update_epic_dates_from_milestones.rb

+# frozen_string_literal: true
+
+class UpdateEpicDatesFromMilestones < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  class Epic < ActiveRecord::Base
+    self.table_name = 'epics'
+    include EachBatch
+
+    has_many :epic_issues
+    has_many :issues, through: :epic_issues
+
+    def self.update_start_and_due_dates(epics)
+      groups = epics.includes(:issues).group_by do |epic|
+        milestone_ids = epic.issues.map(&:milestone_id)
+        milestone_ids.compact!
+        milestone_ids.uniq!
+        milestone_ids
+      end
+
+      groups.each do |milestone_ids, epics|
+        next if milestone_ids.empty?
+
+        data = ::UpdateEpicDatesFromMilestones::Epics::DateSourcingMilestonesFinder.new(epics.first.id)
+
+        self.where(id: epics.map(&:id)).update_all(
+          [
+            %{
+              start_date = CASE WHEN start_date_is_fixed = true THEN start_date ELSE ? END,
+              start_date_sourcing_milestone_id = ?,
+              end_date = CASE WHEN due_date_is_fixed = true THEN end_date ELSE ? END,
+              due_date_sourcing_milestone_id = ?
+            },
+            data.start_date,
+            data.start_date_sourcing_milestone_id,
+            data.due_date,
+            data.due_date_sourcing_milestone_id
+          ]
+        )
+      end
+    end
+  end
+
+  module Epics
+    class DateSourcingMilestonesFinder
+      include Gitlab::Utils::StrongMemoize
+
+      FIELDS = [:id, :start_date, :due_date].freeze
+      ID_INDEX = FIELDS.index(:id)
+      START_DATE_INDEX = FIELDS.index(:start_date)
+      DUE_DATE_INDEX = FIELDS.index(:due_date)
+
+      def initialize(epic_id)
+        @epic_id = epic_id
+      end
+
+      def execute
+        strong_memoize(:execute) do
+          Milestone.joins(issues: :epic_issue).where(epic_issues: { epic_id: epic_id }).joins(
+            <<~SQL
+            INNER JOIN (
+              SELECT MIN(milestones.start_date) AS start_date, MAX(milestones.due_date) AS due_date
+              FROM milestones
+              INNER JOIN issues ON issues.milestone_id = milestones.id
+              INNER JOIN epic_issues ON epic_issues.issue_id = issues.id
+              WHERE epic_issues.epic_id = #{epic_id}
+            ) inner_results ON (inner_results.start_date = milestones.start_date OR inner_results.due_date = milestones.due_date)
+          SQL
+          ).pluck(*FIELDS)
+        end
+      end
+
+      def start_date
+        start_date_sourcing_milestone&.slice(START_DATE_INDEX)
+      end
+
+      def start_date_sourcing_milestone_id
+        start_date_sourcing_milestone&.slice(ID_INDEX)
+      end
+
+      def due_date
+        due_date_sourcing_milestone&.slice(DUE_DATE_INDEX)
+      end
+
+      def due_date_sourcing_milestone_id
+        due_date_sourcing_milestone&.slice(ID_INDEX)
+      end
+
+      private
+
+      attr_reader :epic_id
+
+      def start_date_sourcing_milestone
+        @start_date_sourcing_milestone ||= execute
+          .reject { |row| row[START_DATE_INDEX].nil? }
+          .min_by { |row| row[START_DATE_INDEX] }
+      end
+
+      def due_date_sourcing_milestone
+        @due_date_sourcing_milestone ||= execute
+          .reject { |row| row[DUE_DATE_INDEX].nil? }
+          .max_by { |row| row[DUE_DATE_INDEX] }
+      end
+    end
+  end
+
+  def up
+    # Fill fixed date columns for remaining eligible records touched after regular migration is run
+    # (20180711014026_update_date_columns_on_epics) but before new app code takes effect.
+    Epic.where(start_date_is_fixed: nil).where.not(start_date: nil).each_batch do |batch|
+      batch.update_all('start_date_is_fixed = true, start_date_fixed = start_date')
+    end
+    Epic.where(due_date_is_fixed: nil).where.not(end_date: nil).each_batch do |batch|
+      batch.update_all('due_date_is_fixed = true, due_date_fixed = end_date')
+    end
+
+    Epic.joins(:issues).where('issues.milestone_id IS NOT NULL').each_batch do |epics|
+      Epic.update_start_and_due_dates(epics)
+    end
+  end
+
+  def down
+    # NOOP
+  end
+end

ee/lib/api/epic_issues.rb

@@ -53,7 +53,7 @@ module API
         # For now we return empty body
         # The issues list in the correct order in body will be returned as part of #4250
         if result
-          present epic.issues(current_user),
+          present epic.issues_readable_by(current_user),
             with: EE::API::Entities::EpicIssue,
             current_user: current_user
         else
@@ -70,7 +70,7 @@ module API
       get ':id/(-/)epics/:epic_iid/issues' do
         authorize_can_read!
 
-        present epic.issues(current_user),
+        present epic.issues_readable_by(current_user),
           with: EE::API::Entities::EpicIssue,
           current_user: current_user
       end

ee/lib/api/epics.rb

@@ -58,7 +58,7 @@ module API
         optional :labels, type: String, desc: 'Comma-separated list of label names'
       end
       get ':id/(-/)epics' do
-        present find_epics(group_id: user_group.id), with: EE::API::Entities::Epic
+        present find_epics(group_id: user_group.id), with: EE::API::Entities::Epic, user: current_user
       end
 
       desc 'Get details of an epic' do
@@ -70,7 +70,7 @@ module API
       get ':id/(-/)epics/:epic_iid' do
         authorize_can_read!
 
-        present epic, with: EE::API::Entities::Epic
+        present epic, with: EE::API::Entities::Epic, user: current_user
       end
 
       desc 'Create a new epic' do
@@ -79,8 +79,10 @@ module API
       params do
         requires :title, type: String, desc: 'The title of an epic'
         optional :description, type: String, desc: 'The description of an epic'
-        optional :start_date, type: String, desc: 'The start date of an epic'
-        optional :end_date, type: String, desc: 'The end date of an epic'
+        optional :start_date, as: :start_date_fixed, type: String, desc: 'The start date of an epic'
+        optional :start_date_is_fixed, type: Boolean, desc: 'Indicates start date should be sourced from start_date_fixed field not the issue milestones'
+        optional :end_date, as: :due_date_fixed, type: String, desc: 'The due date of an epic'
+        optional :due_date_is_fixed, type: Boolean, desc: 'Indicates due date should be sourced from due_date_fixed field not the issue milestones'
         optional :labels, type: String, desc: 'Comma-separated list of label names'
       end
       post ':id/(-/)epics' do
@@ -88,7 +90,7 @@ module API
 
         epic = ::Epics::CreateService.new(user_group, current_user, declared_params(include_missing: false)).execute
         if epic.valid?
-          present epic, with: EE::API::Entities::Epic
+          present epic, with: EE::API::Entities::Epic, user: current_user
         else
           render_validation_error!(epic)
         end
@@ -101,10 +103,12 @@ module API
         requires :epic_iid, type: Integer, desc: 'The internal ID of an epic'
         optional :title, type: String, desc: 'The title of an epic'
         optional :description, type: String, desc: 'The description of an epic'
-        optional :start_date, type: String, desc: 'The start date of an epic'
-        optional :end_date, type: String, desc: 'The end date of an epic'
+        optional :start_date, as: :start_date_fixed, type: String, desc: 'The start date of an epic'
+        optional :start_date_is_fixed, type: Boolean, desc: 'Indicates start date should be sourced from start_date_fixed field not the issue milestones'
+        optional :end_date, as: :due_date_fixed, type: String, desc: 'The due date of an epic'
+        optional :due_date_is_fixed, type: Boolean, desc: 'Indicates due date should be sourced from due_date_fixed field not the issue milestones'
         optional :labels, type: String, desc: 'Comma-separated list of label names'
-        at_least_one_of :title, :description, :start_date, :end_date, :labels
+        at_least_one_of :title, :description, :start_date_fixed, :due_date_fixed, :labels
       end
       put ':id/(-/)epics/:epic_iid' do
         authorize_can_admin!
@@ -114,7 +118,7 @@ module API
         result = ::Epics::UpdateService.new(user_group, current_user, update_params).execute(epic)
 
         if result.valid?
-          present result, with: EE::API::Entities::Epic
+          present result, with: EE::API::Entities::Epic, user: current_user
         else
           render_validation_error!(result)
         end

ee/lib/ee/api/entities.rb

@@ -164,6 +164,8 @@ module EE
       end
 
       class Epic < Grape::Entity
+        can_admin_epic = ->(epic, opts) { Ability.allowed?(opts[:user], :admin_epic, epic) }
+
         expose :id
         expose :iid
         expose :group_id
@@ -171,7 +173,12 @@ module EE
         expose :description
         expose :author, using: ::API::Entities::UserBasic
         expose :start_date
-        expose :end_date
+        expose :start_date_is_fixed?, as: :start_date_is_fixed, if: can_admin_epic
+        expose :start_date_fixed, :start_date_from_milestones, if: can_admin_epic
+        expose :end_date # @deprecated
+        expose :end_date, as: :due_date
+        expose :due_date_is_fixed?, as: :due_date_is_fixed, if: can_admin_epic
+        expose :due_date_fixed, :due_date_from_milestones, if: can_admin_epic
         expose :created_at
         expose :updated_at
         expose :labels do |epic, options|

ee/spec/controllers/groups/epics_controller_spec.rb

@@ -181,9 +181,11 @@ describe Groups::EpicsController do
     end
 
     describe 'PUT #update' do
+      let(:date) { Date.new(2002, 1, 1)}
+
       before do
         group.add_developer(user)
-        put :update, group_id: group, id: epic.to_param, epic: { title: 'New title', label_ids: [label.id] }, format: :json
+        put :update, group_id: group, id: epic.to_param, epic: { title: 'New title', label_ids: [label.id], start_date_fixed: '2002-01-01', start_date_is_fixed: true }, format: :json
       end
 
       it 'returns status 200' do
@@ -195,6 +197,9 @@ describe Groups::EpicsController do
 
         expect(epic.title).to eq('New title')
         expect(epic.labels).to eq([label])
+        expect(epic.start_date_fixed).to eq(date)
+        expect(epic.start_date).to eq(date)
+        expect(epic.start_date_is_fixed).to eq(true)
       end
     end
 

ee/spec/factories/epics.rb

@@ -4,6 +4,15 @@ FactoryBot.define do
     group
     author
 
+    trait :use_fixed_dates do
+      start_date { Date.new(2010, 1, 1) }
+      start_date_fixed { Date.new(2010, 1, 1) }
+      start_date_is_fixed true
+      end_date { Date.new(2010, 1, 3) }
+      due_date_fixed { Date.new(2010, 1, 3) }
+      due_date_is_fixed true
+    end
+
     factory :labeled_epic do
       transient do
         labels []

ee/spec/finders/epics/date_sourcing_milestones_finder_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Epics::DateSourcingMilestonesFinder do
+  describe '#execute' do
+    it 'returns date and id from milestones' do
+      epic = create(:epic)
+      milestone1 = create(:milestone, start_date: Date.new(2000, 1, 1), due_date: Date.new(2000, 1, 10))
+      milestone2 = create(:milestone, due_date: Date.new(2000, 1, 30))
+      milestone3 = create(:milestone, start_date: Date.new(2000, 1, 1), due_date: Date.new(2000, 1, 20))
+      create(:issue, epic: epic, milestone: milestone1)
+      create(:issue, epic: epic, milestone: milestone2)
+      create(:issue, epic: epic, milestone: milestone3)
+
+      results = described_class.new(epic.id)
+
+      expect(results).to have_attributes(
+        start_date: milestone1.start_date,
+        start_date_sourcing_milestone_id: milestone1.id,
+        due_date: milestone2.due_date,
+        due_date_sourcing_milestone_id: milestone2.id
+      )
+    end
+
+    it 'returns date and id from single milestone' do
+      epic = create(:epic)
+      milestone1 = create(:milestone, start_date: Date.new(2000, 1, 1), due_date: Date.new(2000, 1, 10))
+      create(:issue, epic: epic, milestone: milestone1)
+
+      results = described_class.new(epic.id)
+
+      expect(results).to have_attributes(
+        start_date: milestone1.start_date,
+        start_date_sourcing_milestone_id: milestone1.id,
+        due_date: milestone1.due_date,
+        due_date_sourcing_milestone_id: milestone1.id
+      )
+    end
+
+    it 'returns date and id from milestone without date' do
+      epic = create(:epic)
+      milestone1 = create(:milestone, start_date: Date.new(2000, 1, 1))
+      create(:issue, epic: epic, milestone: milestone1)
+
+      results = described_class.new(epic.id)
+
+      expect(results).to have_attributes(
+        start_date: milestone1.start_date,
+        start_date_sourcing_milestone_id: milestone1.id,
+        due_date: nil,
+        due_date_sourcing_milestone_id: nil
+      )
+    end
+
+    it 'handles epics without milestone' do
+      epic = create(:epic)
+
+      results = described_class.new(epic.id)
+
+      expect(results).to have_attributes(
+        start_date: nil,
+        start_date_sourcing_milestone_id: nil,
+        due_date: nil,
+        due_date_sourcing_milestone_id: nil
+      )
+    end
+  end
+end

ee/spec/fixtures/api/schemas/entities/epic.json

@@ -12,7 +12,14 @@
     "milestone_id": { "type": ["string", "null"] },
     "state": { "type": "string" },
     "start_date": { "type": ["date", "null"] },
+    "start_date_fixed": { "type": ["date", "null"] },
+    "start_date_is_fixed": { "type": "boolean" },
+    "start_date_from_milestones": { "type": ["date", "null"] },
     "end_date": { "type": ["date", "null"] },
+    "due_date": { "type": ["date", "null"] },
+    "due_date_fixed": { "type": ["date", "null"] },
+    "due_date_from_milestones": { "type": ["date", "null"] },
+    "due_date_is_fixed": { "type": "boolean" },
     "updated_by_id": { "type": ["string", "null"] },
     "created_at": { "type": "string" },
     "updated_at": { "type": "string" },

ee/spec/fixtures/api/schemas/public_api/v4/epic.json

@@ -24,8 +24,15 @@
         "type": "string"
       }
     },
-    "start_date": { "type": ["string", "null"] },
-    "end_date": { "type": ["string", "null"] },
+    "start_date": { "type": ["date", "null"] },
+    "start_date_fixed": { "type": ["date", "null"] },
+    "start_date_from_milestones": { "type": ["date", "null"] },
+    "start_date_is_fixed": { "type": "boolean" },
+    "end_date": { "type": ["date", "null"] },
+    "due_date": { "type": ["date", "null"] },
+    "due_date_fixed": { "type": ["date", "null"] },
+    "due_date_from_milestones": { "type": ["date", "null"] },
+    "due_date_is_fixed": { "type": "boolean" },
     "created_at": { "type": ["string", "null"] },
     "updated_at": { "type": ["string", "null"] }
   },

ee/spec/fixtures/api/schemas/public_api/v4/epic_issue_link.json

@@ -18,8 +18,15 @@
         "group_id": { "type": "integer" },
         "description": { "type": ["string", "null"] },
         "author": { "type": ["object", "null"] },
-        "start_date": { "type": ["string", "null"] },
-        "end_date": { "type": ["string", "null"] },
+        "start_date": { "type": ["date", "null"] },
+        "start_date_fixed": { "type": ["date", "null"] },
+        "start_date_from_milestones": { "type": ["date", "null"] },
+        "start_date_is_fixed": { "type": "boolean" },
+        "end_date": { "type": ["date", "null"] },
+        "due_date": { "type": ["date", "null"] },
+        "due_date_fixed": { "type": ["date", "null"] },
+        "due_date_from_milestones": { "type": ["date", "null"] },
+        "due_date_is_fixed": { "type": "boolean" },
         "created_at": { "type": ["string", "null"] },
         "updated_at": { "type": ["string", "null"] },
         "labels": {

ee/spec/helpers/epics_helper_spec.rb

@@ -4,18 +4,21 @@ describe EpicsHelper do
   include ApplicationHelper
 
   describe '#epic_show_app_data' do
-    it 'returns the correct json' do
-      user = create(:user)
-      @epic = create(:epic, author: user)
+    let(:user) { create(:user) }
+    let!(:epic) { create(:epic, author: user) }
 
+    before do
       allow(helper).to receive(:current_user).and_return(user)
+      stub_licensed_features(epics: true)
+    end
 
-      data = helper.epic_show_app_data(@epic, initial: {}, author_icon: 'icon_path')
+    it 'returns the correct json' do
+      data = helper.epic_show_app_data(epic, initial: {}, author_icon: 'icon_path')
       meta_data = JSON.parse(data[:meta])
 
       expected_keys = %i(initial meta namespace labels_path toggle_subscription_path labels_web_url epics_web_url)
       expect(data.keys).to match_array(expected_keys)
-      expect(meta_data.keys).to match_array(%w[created author start_date end_date epic_id todo_exists todo_path])
+      expect(meta_data.keys).to match_array(%w[created author start_date end_date due_date epic_id todo_exists todo_path])
       expect(meta_data['author']).to eq({
         'name' => user.name,
         'url' => "/#{user.username}",
@@ -23,6 +26,40 @@ describe EpicsHelper do
         'src' => 'icon_path'
       })
     end
+
+    context 'when user has edit permission' do
+      let(:milestone) { create(:milestone, title: 'make me a sandwich') }
+
+      let!(:epic) do
+        create(
+          :epic,
+          author: user,
+          start_date_sourcing_milestone: milestone,
+          start_date: Date.new(2000, 1, 1),
+          due_date_sourcing_milestone: milestone,
+          due_date: Date.new(2000, 1, 2)
+        )
+      end
+
+      before do
+        epic.group.add_developer(user)
+      end
+
+      it 'returns extra date fields if user can edit' do
+        data = helper.epic_show_app_data(epic, initial: {}, author_icon: 'icon_path')
+        meta_data = JSON.parse(data[:meta])
+
+        expect(meta_data.keys).to match_array(%w[
+          created author epic_id todo_exists todo_path
+          start_date start_date_fixed start_date_is_fixed start_date_from_milestones start_date_sourcing_milestone_title
+          end_date due_date due_date_fixed due_date_is_fixed due_date_from_milestones due_date_sourcing_milestone_title
+        ])
+        expect(meta_data['start_date']).to eq('2000-01-01')
+        expect(meta_data['start_date_sourcing_milestone_title']).to eq(milestone.title)
+        expect(meta_data['due_date']).to eq('2000-01-02')
+        expect(meta_data['due_date_sourcing_milestone_title']).to eq(milestone.title)
+      end
+    end
   end
 
   describe '#epic_endpoint_query_params' do

ee/spec/migrations/update_epic_dates_from_milestones_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+require Rails.root.join('ee', 'db', 'post_migrate', '20180713171825_update_epic_dates_from_milestones.rb')
+
+describe UpdateEpicDatesFromMilestones, :migration do
+  let(:migration) { described_class.new }
+  let(:users) { table(:users) }
+  let(:namespaces) { table(:namespaces) }
+  let(:epics) { table(:epics) }
+  let(:projects) { table(:projects) }
+  let(:issues) { table(:issues) }
+  let(:epic_issues) { table(:epic_issues) }
+  let(:milestones) { table(:milestones) }
+
+  describe '#up' do
+    before do
+      user = users.create!(email: 'test@example.com', projects_limit: 100, username: 'test')
+      namespaces.create(id: 1, name: 'gitlab-org', path: 'gitlab-org')
+      projects.create!(id: 1, namespace_id: 1, name: 'gitlab1', path: 'gitlab1')
+
+      epics.create!(id: 1, iid: 1, group_id: 1, title: 'epic with start and due dates', title_html: '', author_id: user.id)
+      epics.create!(id: 2, iid: 2, group_id: 1, title: 'epic with only due date', title_html: '', author_id: user.id)
+      epics.create!(id: 3, iid: 3, group_id: 1, title: 'epic without milestone', title_html: '', author_id: user.id)
+
+      milestones.create!(
+        id: 1,
+        iid: 1,
+        project_id: 1,
+        title: 'milestone-1',
+        start_date: Date.new(2000, 1, 1),
+        due_date: Date.new(2000, 1, 10)
+      )
+      milestones.create!(
+        id: 2,
+        iid: 2,
+        project_id: 1,
+        title: 'milestone-2',
+        due_date: Date.new(2000, 1, 30)
+      )
+
+      issues.create!(id: 1, iid: 1, project_id: 1, milestone_id: 1, title: 'issue-1')
+      issues.create!(id: 2, iid: 2, project_id: 1, milestone_id: 2, title: 'issue-2')
+      issues.create!(id: 3, iid: 3, project_id: 1, milestone_id: 2, title: 'issue-2')
+
+      epic_issues.create!(epic_id: 1, issue_id: 1)
+      epic_issues.create!(epic_id: 1, issue_id: 2)
+      epic_issues.create!(epic_id: 2, issue_id: 3)
+    end
+
+    it 'updates dates milestone ids' do
+      migration.up
+
+      expect(Epic.find(1)).to have_attributes(
+        start_date: Date.new(2000, 1, 1),
+        start_date_sourcing_milestone_id: 1,
+        due_date: Date.new(2000, 1, 30),
+        due_date_sourcing_milestone_id: 2
+      )
+      expect(Epic.find(2)).to have_attributes(
+        start_date: nil,
+        start_date_sourcing_milestone_id: nil,
+        due_date: Date.new(2000, 1, 30),
+        due_date_sourcing_milestone_id: 2
+      )
+      expect(Epic.find(3)).to have_attributes(
+        start_date: nil,
+        start_date_sourcing_milestone_id: nil,
+        due_date: nil,
+        due_date_sourcing_milestone_id: nil
+      )
+    end
+  end
+end

ee/spec/models/epic_spec.rb

@@ -7,6 +7,7 @@ describe Epic do
     it { is_expected.to belong_to(:author).class_name('User') }
     it { is_expected.to belong_to(:assignee).class_name('User') }
     it { is_expected.to belong_to(:group) }
+    it { is_expected.to have_many(:epic_issues) }
   end
 
   describe 'validations' do
@@ -84,7 +85,299 @@ describe Epic do
     end
   end
 
-  describe '#issues' do
+  describe '#start_date' do
+    let(:date) { Date.new(2000, 1, 1) }
+
+    context 'is set' do
+      subject { build(:epic, :use_fixed_dates, start_date: date) }
+
+      it 'returns as is' do
+        expect(subject.start_date).to eq(date)
+      end
+    end
+  end
+
+  describe '#start_date_from_milestones' do
+    context 'fixed date' do
+      it 'returns start date from start date sourcing milestone' do
+        subject = create(:epic, :use_fixed_dates)
+        milestone = create(:milestone, :with_dates)
+        subject.start_date_sourcing_milestone = milestone
+
+        expect(subject.start_date_from_milestones).to eq(milestone.start_date)
+      end
+    end
+
+    context 'milestone date' do
+      it 'returns start_date' do
+        subject = create(:epic, start_date: Date.new(2017, 3, 4))
+
+        expect(subject.start_date_from_milestones).to eq(subject.start_date)
+      end
+    end
+  end
+
+  describe '#due_date_from_milestones' do
+    context 'fixed date' do
+      it 'returns due date from due date sourcing milestone' do
+        subject = create(:epic, :use_fixed_dates)
+        milestone = create(:milestone, :with_dates)
+        subject.due_date_sourcing_milestone = milestone
+
+        expect(subject.due_date_from_milestones).to eq(milestone.due_date)
+      end
+    end
+
+    context 'milestone date' do
+      it 'returns due_date' do
+        subject = create(:epic, due_date: Date.new(2017, 3, 4))
+
+        expect(subject.due_date_from_milestones).to eq(subject.due_date)
+      end
+    end
+  end
+
+  describe '#update_start_and_due_dates' do
+    context 'fixed date is set' do
+      subject { create(:epic, :use_fixed_dates, start_date: nil, end_date: nil) }
+
+      it 'updates to fixed date' do
+        subject.update_start_and_due_dates
+
+        expect(subject.start_date).to eq(subject.start_date_fixed)
+        expect(subject.due_date).to eq(subject.due_date_fixed)
+      end
+    end
+
+    context 'fixed date is not set' do
+      subject { create(:epic, start_date: nil, end_date: nil) }
+
+      let(:milestone1) do
+        create(
+          :milestone,
+          start_date: Date.new(2000, 1, 1),
+          due_date: Date.new(2000, 1, 10)
+        )
+      end
+      let(:milestone2) do
+        create(
+          :milestone,
+          start_date: Date.new(2000, 1, 3),
+          due_date: Date.new(2000, 1, 20)
+        )
+      end
+
+      context 'multiple milestones' do
+        before do
+          epic_issue1 = create(:epic_issue, epic: subject)
+          epic_issue1.issue.update(milestone: milestone1)
+          epic_issue2 = create(:epic_issue, epic: subject)
+          epic_issue2.issue.update(milestone: milestone2)
+        end
+
+        context 'complete start and due dates' do
+          it 'updates to milestone dates' do
+            subject.update_start_and_due_dates
+
+            expect(subject.start_date).to eq(milestone1.start_date)
+            expect(subject.due_date).to eq(milestone2.due_date)
+          end
+        end
+
+        context 'without due date' do
+          let(:milestone1) do
+            create(
+              :milestone,
+              start_date: Date.new(2000, 1, 1),
+              due_date: nil
+            )
+          end
+          let(:milestone2) do
+            create(
+              :milestone,
+              start_date: Date.new(2000, 1, 3),
+              due_date: nil
+            )
+          end
+
+          it 'updates to milestone dates' do
+            subject.update_start_and_due_dates
+
+            expect(subject.start_date).to eq(milestone1.start_date)
+            expect(subject.due_date).to eq(nil)
+          end
+        end
+
+        context 'without any dates' do
+          let(:milestone1) do
+            create(
+              :milestone,
+              start_date: nil,
+              due_date: nil
+            )
+          end
+          let(:milestone2) do
+            create(
+              :milestone,
+              start_date: nil,
+              due_date: nil
+            )
+          end
+
+          it 'updates to milestone dates' do
+            subject.update_start_and_due_dates
+
+            expect(subject.start_date).to eq(nil)
+            expect(subject.due_date).to eq(nil)
+          end
+        end
+      end
+
+      context 'without milestone' do
+        before do
+          create(:epic_issue, epic: subject)
+        end
+
+        it 'updates to milestone dates' do
+          subject.update_start_and_due_dates
+
+          expect(subject.start_date).to eq(nil)
+          expect(subject.start_date_sourcing_milestone_id).to eq(nil)
+          expect(subject.due_date).to eq(nil)
+          expect(subject.due_date_sourcing_milestone_id).to eq(nil)
+        end
+      end
+
+      context 'single milestone' do
+        before do
+          epic_issue1 = create(:epic_issue, epic: subject)
+          epic_issue1.issue.update(milestone: milestone1)
+        end
+
+        context 'complete start and due dates' do
+          it 'updates to milestone dates' do
+            subject.update_start_and_due_dates
+
+            expect(subject.start_date).to eq(milestone1.start_date)
+            expect(subject.due_date).to eq(milestone1.due_date)
+          end
+        end
+
+        context 'without due date' do
+          let(:milestone1) do
+            create(
+              :milestone,
+              start_date: Date.new(2000, 1, 1),
+              due_date: nil
+            )
+          end
+
+          it 'updates to milestone dates' do
+            subject.update_start_and_due_dates
+
+            expect(subject.start_date).to eq(milestone1.start_date)
+            expect(subject.due_date).to eq(nil)
+          end
+        end
+
+        context 'without any dates' do
+          let(:milestone1) do
+            create(
+              :milestone,
+              start_date: nil,
+              due_date: nil
+            )
+          end
+
+          it 'updates to milestone dates' do
+            subject.update_start_and_due_dates
+
+            expect(subject.start_date).to eq(nil)
+            expect(subject.due_date).to eq(nil)
+          end
+        end
+      end
+    end
+  end
+
+  describe '.update_start_and_due_dates' do
+    def link_epic_to_milestone(epic, milestone)
+      create(:issue, epic: epic, milestone: milestone)
+    end
+
+    it 'updates in bulk' do
+      milestone1 = create(:milestone, start_date: Date.new(2000, 1, 1), due_date: Date.new(2000, 1, 10))
+      milestone2 = create(:milestone, due_date: Date.new(2000, 1, 30))
+
+      epics = [
+        create(:epic),
+        create(:epic),
+        create(:epic, :use_fixed_dates)
+      ]
+      old_attributes = epics.map(&:attributes)
+
+      link_epic_to_milestone(epics[0], milestone1)
+      link_epic_to_milestone(epics[0], milestone2)
+      link_epic_to_milestone(epics[1], milestone2)
+      link_epic_to_milestone(epics[2], milestone1)
+      link_epic_to_milestone(epics[2], milestone2)
+
+      described_class.update_start_and_due_dates(described_class.where(id: epics.map(&:id)))
+
+      epics.each(&:reload)
+
+      expect(epics[0].start_date).to eq(milestone1.start_date)
+      expect(epics[0].start_date_sourcing_milestone).to eq(milestone1)
+      expect(epics[0].due_date).to eq(milestone2.due_date)
+      expect(epics[0].due_date_sourcing_milestone).to eq(milestone2)
+
+      expect(epics[1].start_date).to eq(nil)
+      expect(epics[1].start_date_sourcing_milestone).to eq(nil)
+      expect(epics[1].due_date).to eq(milestone2.due_date)
+      expect(epics[1].due_date_sourcing_milestone).to eq(milestone2)
+
+      expect(epics[2].start_date).to eq(old_attributes[2]['start_date'])
+      expect(epics[2].start_date_sourcing_milestone).to eq(milestone1)
+      expect(epics[2].due_date).to eq(old_attributes[2]['end_date'])
+      expect(epics[2].due_date_sourcing_milestone).to eq(milestone2)
+    end
+
+    context 'query count check' do
+      let(:milestone) { create(:milestone, start_date: Date.new(2000, 1, 1), due_date: Date.new(2000, 1, 10)) }
+      let!(:epics) { [create(:epic)] }
+
+      def setup_control_group
+        link_epic_to_milestone(epics[0], milestone)
+
+        ActiveRecord::QueryRecorder.new do
+          described_class.update_start_and_due_dates(described_class.where(id: epics.map(&:id)))
+        end.count
+      end
+
+      it 'does not increase query count when adding epics without milestones' do
+        control_count = setup_control_group
+
+        epics << create(:epic)
+
+        expect do
+          described_class.update_start_and_due_dates(described_class.where(id: epics.map(&:id)))
+        end.not_to exceed_query_limit(control_count)
+      end
+
+      it 'does not increase query count when adding epics belongs to same milestones' do
+        control_count = setup_control_group
+
+        epics << create(:epic)
+        link_epic_to_milestone(epics[1], milestone)
+
+        expect do
+          described_class.update_start_and_due_dates(described_class.where(id: epics.map(&:id)))
+        end.not_to exceed_query_limit(control_count)
+      end
+    end
+  end
+
+  describe '#issues_readable_by' do
     let(:user) { create(:user) }
     let(:group) { create(:group, :private) }
     let(:project) { create(:project, group: group) }
@@ -101,7 +394,7 @@ describe Epic do
       ]
     end
 
-    let(:result) { epic.issues(user) }
+    let(:result) { epic.issues_readable_by(user) }
 
     it 'returns all issues if a user has access to them' do
       group.add_developer(user)

ee/spec/requests/api/epics_spec.rb

@@ -40,6 +40,32 @@ describe API::Epics do
     end
   end
 
+  shared_examples 'can admin epics' do
+    let(:extra_date_fields) { %w[start_date_is_fixed start_date_fixed due_date_is_fixed due_date_fixed] }
+
+    context 'when permission is absent' do
+      RSpec::Matchers.define_negated_matcher :exclude, :include
+
+      it 'returns epic with extra date fields' do
+        get api(url, user), params
+
+        expect(Array.wrap(JSON.parse(response.body))).to all(exclude(*extra_date_fields))
+      end
+    end
+
+    context 'when permission is present' do
+      before do
+        group.add_maintainer(user)
+      end
+
+      it 'returns epic with extra date fields' do
+        get api(url, user), params
+
+        expect(Array.wrap(JSON.parse(response.body))).to all(include(*extra_date_fields))
+      end
+    end
+  end
+
   describe 'GET /groups/:id/epics' do
     let(:url) { "/groups/#{group.path}/epics" }
 
@@ -138,6 +164,8 @@ describe API::Epics do
 
         expect_array_response([epic2.id])
       end
+
+      it_behaves_like 'can admin epics'
     end
   end
 
@@ -149,17 +177,21 @@ describe API::Epics do
     context 'when the request is correct' do
       before do
         stub_licensed_features(epics: true)
-
-        get api(url, user)
       end
 
       it 'returns 200 status' do
+        get api(url, user)
+
         expect(response).to have_gitlab_http_status(200)
       end
 
       it 'matches the response schema' do
+        get api(url, user)
+
         expect(response).to match_response_schema('public_api/v4/epic', dir: 'ee')
       end
+
+      it_behaves_like 'can admin epics'
     end
   end
 
@@ -206,13 +238,26 @@ describe API::Epics do
           expect(epic.description).to eq('epic description')
           expect(epic.labels.first.title).to eq('label1')
         end
+
+        context 'when deprecated start_date and end_date params are present' do
+          let(:start_date) { Date.new(2001, 1, 1) }
+          let(:due_date) { Date.new(2001, 1, 2) }
+          let(:params) { { title: 'new epic', start_date: start_date, end_date: due_date } }
+
+          it 'updates start_date_fixed and due_date_fixed' do
+            result = Epic.last
+
+            expect(result.start_date_fixed).to eq(start_date)
+            expect(result.due_date_fixed).to eq(due_date)
+          end
+        end
       end
     end
   end
 
   describe 'PUT /groups/:id/epics/:epic_iid' do
     let(:url) { "/groups/#{group.path}/epics/#{epic.iid}" }
-    let(:params) { { title: 'new title', description: 'new description', labels: 'label2' } }
+    let(:params) { { title: 'new title', description: 'new description', labels: 'label2', start_date_fixed: "2018-07-17", start_date_is_fixed: true } }
 
     it_behaves_like 'error requests'
 
@@ -260,6 +305,23 @@ describe API::Epics do
           expect(result.title).to eq('new title')
           expect(result.description).to eq('new description')
           expect(result.labels.first.title).to eq('label2')
+          expect(result.start_date).to eq(Date.new(2018, 7, 17))
+          expect(result.start_date_fixed).to eq(Date.new(2018, 7, 17))
+          expect(result.start_date_is_fixed).to eq(true)
+        end
+
+        context 'when deprecated start_date and end_date params are present' do
+          let(:epic) { create(:epic, :use_fixed_dates, group: group) }
+          let(:new_start_date) { epic.start_date + 1.day }
+          let(:new_due_date) { epic.end_date + 1.day }
+          let!(:params) { { start_date: new_start_date, end_date: new_due_date } }
+
+          it 'updates start_date_fixed and due_date_fixed' do
+            result = epic.reload
+
+            expect(result.start_date_fixed).to eq(new_start_date)
+            expect(result.due_date_fixed).to eq(new_due_date)
+          end
         end
       end
     end

ee/spec/services/ee/issues/update_service_spec.rb

+# frozen_string_literal: true
+require 'spec_helper'
+
+describe Issues::UpdateService do
+  let(:issue) { create(:issue) }
+  let(:user) { issue.author }
+  let(:project) { issue.project }
+
+  describe 'execute' do
+    def update_issue(opts)
+      described_class.new(project, user, opts).execute(issue)
+    end
+
+    context 'refresh epic dates' do
+      let(:epic) { create(:epic) }
+      let(:issue) { create(:issue, epic: epic) }
+
+      context 'updating milestone' do
+        let(:milestone) { create(:milestone) }
+
+        it 'calls epic#update_start_and_due_dates' do
+          expect(epic).to receive(:update_start_and_due_dates).twice
+
+          update_issue(milestone: milestone)
+          update_issue(milestone_id: nil)
+        end
+      end
+
+      context 'updating other fields' do
+        it 'does not call epic#update_start_and_due_dates' do
+          expect(epic).not_to receive(:update_start_and_due_dates)
+          update_issue(title: 'foo')
+        end
+      end
+    end
+  end
+end

ee/spec/services/epic_issues/create_service_spec.rb

@@ -268,6 +268,14 @@ describe EpicIssues::CreateService do
 
         include_examples 'returns an error'
       end
+
+      context 'refresh epic dates' do
+        it 'calls epic#update_start_and_due_dates' do
+          expect(epic).to receive(:update_start_and_due_dates)
+
+          assign_issue([valid_reference])
+        end
+      end
     end
   end
 end

ee/spec/services/epic_issues/destroy_service_spec.rb

@@ -75,6 +75,14 @@ describe EpicIssues::DestroyService do
           is_expected.to eq(message: 'No Issue Link found', status: :error, http_status: 404)
         end
       end
+
+      context 'refresh epic dates' do
+        it 'calls epic#update_start_and_due_dates' do
+          expect(epic).to receive(:update_start_and_due_dates)
+
+          subject
+        end
+      end
     end
   end
 end

ee/spec/services/epics/update_service_spec.rb

@@ -18,8 +18,10 @@ describe Epics::UpdateService do
         {
           title: 'New title',
           description: 'New description',
-          start_date: '2017-01-09',
-          end_date: '2017-10-21'
+          start_date_fixed: '2017-01-09',
+          start_date_is_fixed: true,
+          due_date_fixed: '2017-10-21',
+          due_date_is_fixed: true
         }
       end
 
@@ -27,10 +29,11 @@ describe Epics::UpdateService do
         update_epic(opts)
 
         expect(epic).to be_valid
-        expect(epic.title).to eq(opts[:title])
-        expect(epic.description).to eq(opts[:description])
-        expect(epic.start_date).to eq(Date.strptime(opts[:start_date]))
-        expect(epic.end_date).to eq(Date.strptime(opts[:end_date]))
+        expect(epic).to have_attributes(opts.except(:due_date_fixed, :start_date_fixed))
+        expect(epic).to have_attributes(
+          start_date_fixed: Date.strptime(opts[:start_date_fixed]),
+          due_date_fixed: Date.strptime(opts[:due_date_fixed])
+        )
       end
 
       it 'updates the last_edited_at value' do
@@ -115,5 +118,32 @@ describe Epics::UpdateService do
         end
       end
     end
+
+    context 'filter out start_date and end_date' do
+      it 'ignores start_date and end_date' do
+        expect { update_epic(start_date: Date.today, end_date: Date.today) }.not_to change { Note.count }
+
+        expect(epic).to be_valid
+        expect(epic).to have_attributes(start_date: nil, due_date: nil)
+      end
+    end
+
+    context 'refresh epic dates' do
+      context 'date fields are updated' do
+        it 'calls epic#update_start_and_due_dates' do
+          expect(epic).to receive(:update_start_and_due_dates)
+
+          update_epic(start_date_is_fixed: true, start_date_fixed: Date.today)
+        end
+      end
+
+      context 'date fields are not updated' do
+        it 'does not call epic#update_start_and_due_dates' do
+          expect(epic).not_to receive(:update_start_and_due_dates)
+
+          update_epic(title: 'foo')
+        end
+      end
+    end
   end
 end

ee/spec/services/milestones/update_service_spec.rb

+# frozen_string_literal: true
+require 'spec_helper'
+
+describe Milestones::UpdateService do
+  describe '#execute' do
+    context 'refresh related epic dates' do
+      it 'updates milestone sourced dates' do
+        project = create(:project)
+        user = build(:user)
+        milestone = create(:milestone, project: project)
+        epic = create(:epic)
+        create(:issue, milestone: milestone, epic: epic)
+        due_date = 3.days.from_now.to_date
+
+        described_class.new(project, user, { due_date: due_date }).execute(milestone)
+
+        expect(epic.reload).to have_attributes(
+          start_date: nil,
+          start_date_sourcing_milestone: nil,
+          due_date: due_date,
+          due_date_sourcing_milestone: milestone
+        )
+      end
+    end
+  end
+end

spec/factories/milestones.rb

@@ -18,6 +18,11 @@ FactoryBot.define do
       state "closed"
     end
 
+    trait :with_dates do
+      start_date { Date.new(2000, 1, 1) }
+      due_date { Date.new(2000, 1, 30) }
+    end
+
     after(:build, :stub) do |milestone, evaluator|
       if evaluator.group
         milestone.group = evaluator.group

spec/services/milestones/update_service_spec.rb

+# frozen_string_literal: true
+require 'spec_helper'
+
+describe Milestones::UpdateService do
+  let(:project) { create(:project) }
+  let(:user) { build(:user) }
+  let(:milestone) { create(:milestone, project: project) }
+
+  describe '#execute' do
+    context "valid params" do
+      let(:inner_service) { double(:service) }
+
+      before do
+        project.add_maintainer(user)
+      end
+
+      subject { described_class.new(project, user, { title: 'new_title' }).execute(milestone) }
+
+      it { expect(subject).to be_valid }
+      it { expect(subject.title).to eq('new_title') }
+
+      context 'state_event is activate' do
+        it 'calls ReopenService' do
+          expect(Milestones::ReopenService).to receive(:new).with(project, user, {}).and_return(inner_service)
+          expect(inner_service).to receive(:execute).with(milestone)
+
+          described_class.new(project, user, { state_event: 'activate' }).execute(milestone)
+        end
+      end
+
+      context 'state_event is close' do
+        it 'calls ReopenService' do
+          expect(Milestones::CloseService).to receive(:new).with(project, user, {}).and_return(inner_service)
+          expect(inner_service).to receive(:execute).with(milestone)
+
+          described_class.new(project, user, { state_event: 'close' }).execute(milestone)
+        end
+      end
+    end
+  end
+end

spec/services/notes/create_service_spec.rb

@@ -145,7 +145,11 @@ describe Notes::CreateService do
           let(:note_text) { %(HELLO\n/close\n/assign @#{user.username}\nWORLD) }
 
           it 'saves the note and does not alter the note text' do
-            expect_any_instance_of(Issues::UpdateService).to receive(:execute).and_call_original
+            service = instance_double('Issues::UpdateService', :service)
+
+            allow(Issues::UpdateService).to receive(:new).and_return(service)
+
+            expect(service).to receive(:execute)
 
             note = described_class.new(project, user, opts.merge(note: note_text)).execute
 

spec/support/shared_examples/services/boards/issues_move_service.rb

@@ -4,7 +4,11 @@ shared_examples 'issues move service' do |group|
     let(:params) { { board_id: board1.id, from_list_id: list1.id, to_list_id: list2.id } }
 
     it 'delegates the label changes to Issues::UpdateService' do
-      expect_any_instance_of(Issues::UpdateService).to receive(:execute).with(issue).once
+      service = instance_double('Issues::UpdateService', :service)
+
+      allow(Issues::UpdateService).to receive(:new).and_return(service)
+
+      expect(service).to receive(:execute).with(issue).once
 
       described_class.new(parent, user, params).execute(issue)
     end