Merge branch 'epic_boards_graphql_lists' into 'master'

Add epic boards lists and expose it in GraphQL API

See merge request gitlab-org/gitlab!49728

changelogs/unreleased/epic_boards_graphql_lists.yml

+---
+title: Add epic board list table
+merge_request: 49728
+author:
+type: added

db/migrate/20201214184020_add_epic_board_list.rb

+# frozen_string_literal: true
+
+class AddEpicBoardList < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    unless table_exists?(:boards_epic_lists)
+      with_lock_retries do
+        create_table :boards_epic_lists do |t|
+          t.timestamps_with_timezone
+          t.references :epic_board, index: true, foreign_key: { to_table: :boards_epic_boards, on_delete: :cascade }, null: false
+          t.references :label, index: true, foreign_key: { on_delete: :cascade }
+          t.integer :position
+          t.integer :list_type, default: 1, limit: 2, null: false
+
+          t.index [:epic_board_id, :label_id], unique: true, where: 'list_type = 1', name: 'index_boards_epic_lists_on_epic_board_id_and_label_id'
+        end
+      end
+    end
+
+    add_check_constraint :boards_epic_lists, '(list_type <> 1) OR ("position" IS NOT NULL AND "position" >= 0)', 'boards_epic_lists_position_constraint'
+  end
+
+  def down
+    with_lock_retries do
+      drop_table :boards_epic_lists
+    end
+  end
+end

db/schema_migrations/20201214184020

+adce3c714064991e93f8a587da3d5892c47dbc14963fa49638ebbbf8b5489359
\ No newline at end of file

db/structure.sql

@@ -9909,6 +9909,26 @@ CREATE SEQUENCE boards_epic_boards_id_seq
 
 ALTER SEQUENCE boards_epic_boards_id_seq OWNED BY boards_epic_boards.id;
 
+CREATE TABLE boards_epic_lists (
+    id bigint NOT NULL,
+    created_at timestamp with time zone NOT NULL,
+    updated_at timestamp with time zone NOT NULL,
+    epic_board_id bigint NOT NULL,
+    label_id bigint,
+    "position" integer,
+    list_type smallint DEFAULT 1 NOT NULL,
+    CONSTRAINT boards_epic_lists_position_constraint CHECK (((list_type <> 1) OR (("position" IS NOT NULL) AND ("position" >= 0))))
+);
+
+CREATE SEQUENCE boards_epic_lists_id_seq
+    START WITH 1
+    INCREMENT BY 1
+    NO MINVALUE
+    NO MAXVALUE
+    CACHE 1;
+
+ALTER SEQUENCE boards_epic_lists_id_seq OWNED BY boards_epic_lists.id;
+
 CREATE TABLE boards_epic_user_preferences (
     id bigint NOT NULL,
     board_id bigint NOT NULL,
@@ -18130,6 +18150,8 @@ ALTER TABLE ONLY boards_epic_board_positions ALTER COLUMN id SET DEFAULT nextval
 
 ALTER TABLE ONLY boards_epic_boards ALTER COLUMN id SET DEFAULT nextval('boards_epic_boards_id_seq'::regclass);
 
+ALTER TABLE ONLY boards_epic_lists ALTER COLUMN id SET DEFAULT nextval('boards_epic_lists_id_seq'::regclass);
+
 ALTER TABLE ONLY boards_epic_user_preferences ALTER COLUMN id SET DEFAULT nextval('boards_epic_user_preferences_id_seq'::regclass);
 
 ALTER TABLE ONLY broadcast_messages ALTER COLUMN id SET DEFAULT nextval('broadcast_messages_id_seq'::regclass);
@@ -19173,6 +19195,9 @@ ALTER TABLE ONLY boards_epic_board_positions
 ALTER TABLE ONLY boards_epic_boards
     ADD CONSTRAINT boards_epic_boards_pkey PRIMARY KEY (id);
 
+ALTER TABLE ONLY boards_epic_lists
+    ADD CONSTRAINT boards_epic_lists_pkey PRIMARY KEY (id);
+
 ALTER TABLE ONLY boards_epic_user_preferences
     ADD CONSTRAINT boards_epic_user_preferences_pkey PRIMARY KEY (id);
 
@@ -20824,6 +20849,12 @@ CREATE INDEX index_boards_epic_board_positions_on_epic_id ON boards_epic_board_p
 
 CREATE INDEX index_boards_epic_boards_on_group_id ON boards_epic_boards USING btree (group_id);
 
+CREATE INDEX index_boards_epic_lists_on_epic_board_id ON boards_epic_lists USING btree (epic_board_id);
+
+CREATE UNIQUE INDEX index_boards_epic_lists_on_epic_board_id_and_label_id ON boards_epic_lists USING btree (epic_board_id, label_id) WHERE (list_type = 1);
+
+CREATE INDEX index_boards_epic_lists_on_label_id ON boards_epic_lists USING btree (label_id);
+
 CREATE INDEX index_boards_epic_user_preferences_on_board_id ON boards_epic_user_preferences USING btree (board_id);
 
 CREATE UNIQUE INDEX index_boards_epic_user_preferences_on_board_user_epic_unique ON boards_epic_user_preferences USING btree (board_id, user_id, epic_id);
@@ -24029,6 +24060,9 @@ ALTER TABLE ONLY user_synced_attributes_metadata
 ALTER TABLE ONLY project_authorizations
     ADD CONSTRAINT fk_rails_0f84bb11f3 FOREIGN KEY (project_id) REFERENCES projects(id) ON DELETE CASCADE;
 
+ALTER TABLE ONLY boards_epic_lists
+    ADD CONSTRAINT fk_rails_0f9c7f646f FOREIGN KEY (epic_board_id) REFERENCES boards_epic_boards(id) ON DELETE CASCADE;
+
 ALTER TABLE ONLY issue_email_participants
     ADD CONSTRAINT fk_rails_0fdfd8b811 FOREIGN KEY (issue_id) REFERENCES issues(id) ON DELETE CASCADE;
 
@@ -24134,6 +24168,9 @@ ALTER TABLE ONLY boards_epic_board_positions
 ALTER TABLE ONLY geo_repository_created_events
     ADD CONSTRAINT fk_rails_1f49e46a61 FOREIGN KEY (project_id) REFERENCES projects(id) ON DELETE CASCADE;
 
+ALTER TABLE ONLY boards_epic_lists
+    ADD CONSTRAINT fk_rails_1fe6b54909 FOREIGN KEY (label_id) REFERENCES labels(id) ON DELETE CASCADE;
+
 ALTER TABLE ONLY approval_merge_request_rules_groups
     ADD CONSTRAINT fk_rails_2020a7124a FOREIGN KEY (group_id) REFERENCES namespaces(id) ON DELETE CASCADE;
 

doc/api/graphql/reference/gitlab_schema.graphql

@@ -2225,6 +2225,11 @@ Identifier of Boards::EpicBoard
 """
 scalar BoardsEpicBoardID
 
+"""
+Identifier of Boards::EpicList
+"""
+scalar BoardsEpicListID
+
 type Branch {
   """
   Commit for the branch
@@ -8093,12 +8098,37 @@ Represents an epic board
 """
 type EpicBoard {
   """
-  Global ID of the board
+  Global ID of the board.
   """
   id: BoardsEpicBoardID!
 
   """
-  Name of the board
+  Epic board lists.
+  """
+  lists(
+    """
+    Returns the elements in the list that come after the specified cursor.
+    """
+    after: String
+
+    """
+    Returns the elements in the list that come before the specified cursor.
+    """
+    before: String
+
+    """
+    Returns the first _n_ elements from the list.
+    """
+    first: Int
+
+    """
+    Returns the last _n_ elements from the list.
+    """
+    last: Int
+  ): EpicListConnection
+
+  """
+  Name of the board.
   """
   name: String
 }
@@ -8693,6 +8723,71 @@ type EpicIssueEdge {
   node: EpicIssue
 }
 
+"""
+Represents an epic board list
+"""
+type EpicList {
+  """
+  Global ID of the board list.
+  """
+  id: BoardsEpicListID!
+
+  """
+  Label of the list.
+  """
+  label: Label
+
+  """
+  Type of the list.
+  """
+  listType: String!
+
+  """
+  Position of the list within the board.
+  """
+  position: Int
+
+  """
+  Title of the list.
+  """
+  title: String!
+}
+
+"""
+The connection type for EpicList.
+"""
+type EpicListConnection {
+  """
+  A list of edges.
+  """
+  edges: [EpicListEdge]
+
+  """
+  A list of nodes.
+  """
+  nodes: [EpicList]
+
+  """
+  Information to aid in pagination.
+  """
+  pageInfo: PageInfo!
+}
+
+"""
+An edge in a connection.
+"""
+type EpicListEdge {
+  """
+  A cursor for use in pagination.
+  """
+  cursor: String!
+
+  """
+  The item at the end of the edge.
+  """
+  node: EpicList
+}
+
 """
 Check permissions for the current user on an epic
 """

doc/api/graphql/reference/gitlab_schema.json

@@ -5899,6 +5899,16 @@
           "enumValues": null,
           "possibleTypes": null
         },
+        {
+          "kind": "SCALAR",
+          "name": "BoardsEpicListID",
+          "description": "Identifier of Boards::EpicList",
+          "fields": null,
+          "inputFields": null,
+          "interfaces": null,
+          "enumValues": null,
+          "possibleTypes": null
+        },
         {
           "kind": "SCALAR",
           "name": "Boolean",
@@ -22633,7 +22643,7 @@
           "fields": [
             {
               "name": "id",
-              "description": "Global ID of the board",
+              "description": "Global ID of the board.",
               "args": [
 
               ],
@@ -22649,9 +22659,62 @@
               "isDeprecated": false,
               "deprecationReason": null
             },
+            {
+              "name": "lists",
+              "description": "Epic board lists.",
+              "args": [
+                {
+                  "name": "after",
+                  "description": "Returns the elements in the list that come after the specified cursor.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "String",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
+                {
+                  "name": "before",
+                  "description": "Returns the elements in the list that come before the specified cursor.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "String",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
+                {
+                  "name": "first",
+                  "description": "Returns the first _n_ elements from the list.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "Int",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
+                {
+                  "name": "last",
+                  "description": "Returns the last _n_ elements from the list.",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "Int",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                }
+              ],
+              "type": {
+                "kind": "OBJECT",
+                "name": "EpicListConnection",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
             {
               "name": "name",
-              "description": "Name of the board",
+              "description": "Name of the board.",
               "args": [
 
               ],
@@ -24375,6 +24438,213 @@
           "enumValues": null,
           "possibleTypes": null
         },
+        {
+          "kind": "OBJECT",
+          "name": "EpicList",
+          "description": "Represents an epic board list",
+          "fields": [
+            {
+              "name": "id",
+              "description": "Global ID of the board list.",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "NON_NULL",
+                "name": null,
+                "ofType": {
+                  "kind": "SCALAR",
+                  "name": "BoardsEpicListID",
+                  "ofType": null
+                }
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
+              "name": "label",
+              "description": "Label of the list.",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "OBJECT",
+                "name": "Label",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
+              "name": "listType",
+              "description": "Type of the list.",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "NON_NULL",
+                "name": null,
+                "ofType": {
+                  "kind": "SCALAR",
+                  "name": "String",
+                  "ofType": null
+                }
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
+              "name": "position",
+              "description": "Position of the list within the board.",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "SCALAR",
+                "name": "Int",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
+              "name": "title",
+              "description": "Title of the list.",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "NON_NULL",
+                "name": null,
+                "ofType": {
+                  "kind": "SCALAR",
+                  "name": "String",
+                  "ofType": null
+                }
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            }
+          ],
+          "inputFields": null,
+          "interfaces": [
+
+          ],
+          "enumValues": null,
+          "possibleTypes": null
+        },
+        {
+          "kind": "OBJECT",
+          "name": "EpicListConnection",
+          "description": "The connection type for EpicList.",
+          "fields": [
+            {
+              "name": "edges",
+              "description": "A list of edges.",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "LIST",
+                "name": null,
+                "ofType": {
+                  "kind": "OBJECT",
+                  "name": "EpicListEdge",
+                  "ofType": null
+                }
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
+              "name": "nodes",
+              "description": "A list of nodes.",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "LIST",
+                "name": null,
+                "ofType": {
+                  "kind": "OBJECT",
+                  "name": "EpicList",
+                  "ofType": null
+                }
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
+              "name": "pageInfo",
+              "description": "Information to aid in pagination.",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "NON_NULL",
+                "name": null,
+                "ofType": {
+                  "kind": "OBJECT",
+                  "name": "PageInfo",
+                  "ofType": null
+                }
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            }
+          ],
+          "inputFields": null,
+          "interfaces": [
+
+          ],
+          "enumValues": null,
+          "possibleTypes": null
+        },
+        {
+          "kind": "OBJECT",
+          "name": "EpicListEdge",
+          "description": "An edge in a connection.",
+          "fields": [
+            {
+              "name": "cursor",
+              "description": "A cursor for use in pagination.",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "NON_NULL",
+                "name": null,
+                "ofType": {
+                  "kind": "SCALAR",
+                  "name": "String",
+                  "ofType": null
+                }
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
+            {
+              "name": "node",
+              "description": "The item at the end of the edge.",
+              "args": [
+
+              ],
+              "type": {
+                "kind": "OBJECT",
+                "name": "EpicList",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            }
+          ],
+          "inputFields": null,
+          "interfaces": [
+
+          ],
+          "enumValues": null,
+          "possibleTypes": null
+        },
         {
           "kind": "OBJECT",
           "name": "EpicPermissions",

doc/api/graphql/reference/index.md

@@ -1377,8 +1377,9 @@ Represents an epic board.
 
 | Field | Type | Description |
 | ----- | ---- | ----------- |
-| `id` | BoardsEpicBoardID! | Global ID of the board |
-| `name` | String | Name of the board |
+| `id` | BoardsEpicBoardID! | Global ID of the board. |
+| `lists` | EpicListConnection | Epic board lists. |
+| `name` | String | Name of the board. |
 
 ### EpicDescendantCount
 
@@ -1472,6 +1473,18 @@ Relationship between an epic and an issue.
 | `webUrl` | String! | Web URL of the issue |
 | `weight` | Int | Weight of the issue. |
 
+### EpicList
+
+Represents an epic board list.
+
+| Field | Type | Description |
+| ----- | ---- | ----------- |
+| `id` | BoardsEpicListID! | Global ID of the board list. |
+| `label` | Label | Label of the list. |
+| `listType` | String! | Type of the list. |
+| `position` | Int | Position of the list within the board. |
+| `title` | String! | Title of the list. |
+
 ### EpicPermissions
 
 Check permissions for the current user on an epic.

ee/app/graphql/resolvers/boards/epic_lists_resolver.rb

+# frozen_string_literal: true
+
+module Resolvers
+  module Boards
+    class EpicListsResolver < BaseResolver
+      include Gitlab::Graphql::Authorize::AuthorizeResource
+      include LooksAhead
+
+      type Types::Boards::EpicListType.connection_type, null: true
+
+      when_single do
+        argument :id, ::Types::GlobalIDType[::Boards::EpicList],
+                 required: true,
+                 description: 'Find an epic board list by ID.'
+      end
+
+      alias_method :epic_board, :object
+
+      def resolve_with_lookahead(id: nil)
+        authorize!
+
+        # eventually we may want to (re)use Boards::Lists::ListService
+        # but we don't support yet creation of default lists so at this
+        # point there is not reason to introduce a ListService
+        # https://gitlab.com/gitlab-org/gitlab/-/issues/294043
+        lists = epic_board.epic_lists
+        lists = lists.where(id: id.model_id) if id # rubocop: disable CodeReuse/ActiveRecord
+
+        offset_pagination(apply_lookahead(lists))
+      end
+
+      private
+
+      def authorize!
+        Ability.allowed?(context[:current_user], :read_epic_list, epic_board.group) || raise_resource_not_available_error!
+      end
+
+      def preloads
+        {
+          label: [:label]
+        }
+      end
+    end
+  end
+end

ee/app/graphql/types/boards/epic_board_type.rb

@@ -10,10 +10,17 @@ module Types
       authorize :read_epic_board
 
       field :id, type: ::Types::GlobalIDType[::Boards::EpicBoard], null: false,
-            description: 'Global ID of the board'
+            description: 'Global ID of the board.'
 
       field :name, type: GraphQL::STRING_TYPE, null: true,
-            description: 'Name of the board'
+            description: 'Name of the board.'
+
+      field :lists,
+            Types::Boards::EpicListType.connection_type,
+            null: true,
+            description: 'Epic board lists.',
+            extras: [:lookahead],
+            resolver: Resolvers::Boards::EpicListsResolver
     end
   end
 end

ee/app/graphql/types/boards/epic_list_type.rb

+# frozen_string_literal: true
+
+module Types
+  module Boards
+    # rubocop: disable Graphql/AuthorizeTypes
+    class EpicListType < BaseObject
+      graphql_name 'EpicList'
+      description 'Represents an epic board list'
+
+      accepts ::Boards::EpicList
+
+      field :id, type: ::Types::GlobalIDType[::Boards::EpicList], null: false,
+            description: 'Global ID of the board list.'
+
+      field :title, GraphQL::STRING_TYPE, null: false,
+            description: 'Title of the list.'
+
+      field :list_type, GraphQL::STRING_TYPE, null: false,
+            description: 'Type of the list.'
+
+      field :position, GraphQL::INT_TYPE, null: true,
+            description: 'Position of the list within the board.'
+
+      field :label, Types::LabelType, null: true,
+            description: 'Label of the list.'
+    end
+    # rubocop: enable Graphql/AuthorizeTypes
+  end
+end

ee/app/models/boards/epic_board.rb

@@ -5,6 +5,7 @@ module Boards
     belongs_to :group, optional: false, inverse_of: :epic_boards
     has_many :epic_board_labels, foreign_key: :epic_board_id, inverse_of: :epic_board
     has_many :epic_board_positions, foreign_key: :epic_board_id, inverse_of: :epic_board
+    has_many :epic_lists, -> { ordered }, foreign_key: :epic_board_id, inverse_of: :epic_board
 
     validates :name, length: { maximum: 255 }
 

ee/app/models/boards/epic_list.rb

+# frozen_string_literal: true
+
+module Boards
+  class EpicList < ApplicationRecord
+    belongs_to :epic_board, optional: false, inverse_of: :epic_lists
+    belongs_to :label, inverse_of: :epic_lists
+
+    enum list_type: { backlog: 0, label: 1, closed: 2 }
+
+    validates :label, :position, presence: true, if: :label?
+    validates :label_id, uniqueness: { scope: :epic_board_id }, if: :label?
+    validates :position, numericality: { only_integer: true, greater_than_or_equal_to: 0 }, if: :label?
+
+    scope :ordered, -> { order(:list_type, :position) }
+
+    def title
+      label? ? label.name : list_type.humanize
+    end
+  end
+end

ee/app/models/ee/label.rb

@@ -9,6 +9,7 @@ module EE
 
     prepended do
       has_many :epic_board_labels, class_name: 'Boards::EpicBoardLabel', inverse_of: :label
+      has_many :epic_lists, class_name: 'Boards::EpicList', inverse_of: :label
     end
 
     def scoped_label?

ee/app/policies/ee/group_policy.rb

@@ -176,6 +176,7 @@ module EE
       rule { can?(:read_group) & epics_available }.policy do
         enable :read_epic
         enable :read_epic_board
+        enable :read_epic_list
       end
 
       rule { can?(:read_group) & iterations_available }.enable :read_iteration

ee/spec/factories/boards/epic_lists.rb

+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :epic_list, class: 'Boards::EpicList' do
+    epic_board
+    label
+    list_type { :label }
+    sequence(:position)
+  end
+end

ee/spec/graphql/resolvers/boards/epic_boards_resolvers_spec.rb

@@ -33,7 +33,7 @@ RSpec.describe Resolvers::Boards::EpicBoardsResolver do
       end
 
       it 'raises an error if user cannot read epic boards' do
-        expect { result}.to raise_error(Gitlab::Graphql::Errors::ResourceNotAvailable)
+        expect { result }.to raise_error(Gitlab::Graphql::Errors::ResourceNotAvailable)
       end
 
       context 'when user is member of the group' do
@@ -42,7 +42,7 @@ RSpec.describe Resolvers::Boards::EpicBoardsResolver do
         end
 
         it 'returns epic boards in the group ordered by name' do
-          expect(result).to match_array([epic_board2, epic_board1])
+          expect(result).to eq([epic_board2, epic_board1])
         end
 
         context 'when epic_boards flag is disabled' do

ee/spec/graphql/resolvers/boards/epic_lists_resolvers_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Resolvers::Boards::EpicListsResolver do
+  include GraphqlHelpers
+
+  let_it_be(:user) { create(:user) }
+  let_it_be_with_refind(:group) { create(:group, :private) }
+  let_it_be(:epic_board) { create(:epic_board, group: group) }
+  let_it_be(:epic_list1) { create(:epic_list, epic_board: epic_board) }
+  let_it_be(:epic_list2) { create(:epic_list, epic_board: epic_board) }
+
+  specify do
+    expect(described_class).to have_nullable_graphql_type(Types::Boards::EpicListType.connection_type)
+  end
+
+  describe '#resolve' do
+    let(:args) { {} }
+
+    subject(:result) { resolve(described_class, ctx: { current_user: user }, obj: epic_board, args: args) }
+
+    before do
+      stub_licensed_features(epics: true)
+    end
+
+    it 'raises an error if user cannot read epic lists' do
+      expect { result }.to raise_error(Gitlab::Graphql::Errors::ResourceNotAvailable)
+    end
+
+    context 'when user is member of the group' do
+      before do
+        group.add_reporter(user)
+      end
+
+      it 'returns epic lists for the board' do
+        expect(result.items).to match_array([epic_list1, epic_list2])
+      end
+
+      context 'when list ID param is set' do
+        let(:args) { { id: epic_list1.to_global_id } }
+
+        it 'returns an array with single epic list' do
+          expect(result.items).to match_array([epic_list1])
+        end
+      end
+    end
+  end
+end

ee/spec/graphql/types/boards/epic_board_type_spec.rb

@@ -8,7 +8,7 @@ RSpec.describe GitlabSchema.types['EpicBoard'] do
   specify { expect(described_class).to require_graphql_authorizations(:read_epic_board) }
 
   it 'has specific fields' do
-    expected_fields = %w[id name]
+    expected_fields = %w[id name lists]
 
     expect(described_class).to include_graphql_fields(*expected_fields)
   end

ee/spec/graphql/types/boards/epic_list_type_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe GitlabSchema.types['EpicList'] do
+  specify { expect(described_class.graphql_name).to eq('EpicList') }
+
+  it 'has specific fields' do
+    expected_fields = %w[id title list_type position label]
+
+    expect(described_class).to include_graphql_fields(*expected_fields)
+  end
+end

ee/spec/models/boards/epic_board_spec.rb

@@ -7,6 +7,7 @@ RSpec.describe Boards::EpicBoard do
     it { is_expected.to belong_to(:group).required.inverse_of(:epic_boards) }
     it { is_expected.to have_many(:epic_board_labels).inverse_of(:epic_board) }
     it { is_expected.to have_many(:epic_board_positions).inverse_of(:epic_board) }
+    it { is_expected.to have_many(:epic_lists).order(list_type: :asc, position: :asc).inverse_of(:epic_board) }
   end
 
   describe 'validations' do

ee/spec/models/boards/epic_list_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Boards::EpicList do
+  describe 'associations' do
+    subject { build(:epic_list) }
+
+    it { is_expected.to belong_to(:epic_board).required.inverse_of(:epic_lists) }
+    it { is_expected.to belong_to(:label).inverse_of(:epic_lists) }
+    it { is_expected.to validate_presence_of(:position) }
+    it { is_expected.to validate_numericality_of(:position).only_integer.is_greater_than_or_equal_to(0) }
+    it { is_expected.to validate_uniqueness_of(:label_id).scoped_to(:epic_board_id) }
+
+    context 'when list_type is set to closed' do
+      subject { build(:epic_list, list_type: :closed) }
+
+      it { is_expected.not_to validate_presence_of(:label) }
+      it { is_expected.not_to validate_presence_of(:position) }
+    end
+  end
+
+  describe 'scopes' do
+    describe '.ordered' do
+      it 'returns lists ordered by type and position' do
+        list1 = create(:epic_list, list_type: :backlog)
+        list2 = create(:epic_list, list_type: :closed)
+        list3 = create(:epic_list, position: 1)
+        list4 = create(:epic_list, position: 2)
+
+        expect(described_class.ordered).to eq([list1, list3, list4, list2])
+      end
+    end
+  end
+
+  describe '#title' do
+    it 'returns label name for label lists' do
+      list = build(:epic_list)
+      expect(list.title).to eq(list.label.name)
+    end
+
+    it 'returns list type for non-label lists' do
+      expect(build(:epic_list, list_type: ::Boards::EpicList.list_types[:backlog]).title).to eq('Backlog')
+    end
+  end
+end

ee/spec/models/ee/label_spec.rb

@@ -5,6 +5,7 @@ require 'spec_helper'
 RSpec.describe Label do
   describe 'associations' do
     it { is_expected.to have_many(:epic_board_labels).inverse_of(:label) }
+    it { is_expected.to have_many(:epic_lists).inverse_of(:label) }
   end
 
   describe '#scoped_label?' do

ee/spec/policies/group_policy_spec.rb

@@ -5,7 +5,10 @@ require 'spec_helper'
 RSpec.describe GroupPolicy do
   include_context 'GroupPolicy context'
 
-  let(:epic_rules) { %i(read_epic create_epic admin_epic destroy_epic read_confidential_epic destroy_epic_link read_epic_board) }
+  let(:epic_rules) do
+    %i(read_epic create_epic admin_epic destroy_epic read_confidential_epic
+       destroy_epic_link read_epic_board read_epic_list)
+  end
 
   context 'when epics feature is disabled' do
     let(:current_user) { owner }
@@ -55,7 +58,7 @@ RSpec.describe GroupPolicy do
       let(:current_user) { guest }
 
       it { is_expected.to be_allowed(:read_epic, :read_epic_board) }
-      it { is_expected.to be_disallowed(*(epic_rules - [:read_epic, :read_epic_board])) }
+      it { is_expected.to be_disallowed(*(epic_rules - [:read_epic, :read_epic_board, :read_epic_list])) }
     end
 
     context 'when user is not member' do

ee/spec/requests/api/graphql/boards/epic_lists_query_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'get list of epic boards' do
+  include GraphqlHelpers
+
+  let_it_be(:current_user) { create(:user) }
+  let_it_be(:group) { create(:group, :private) }
+  let_it_be(:board) { create(:epic_board, group: group) }
+  let_it_be(:list1) { create(:epic_list, epic_board: board) }
+  let_it_be(:list2) { create(:epic_list, epic_board: board, list_type: :closed) }
+  let_it_be(:list3) { create(:epic_list, epic_board: board, list_type: :backlog) }
+
+  def pagination_query(params = {})
+    graphql_query_for(:group, { full_path: group.full_path },
+      <<~BOARDS
+        epicBoard(id: "#{board.to_global_id}") {
+          #{query_nodes(:lists, all_graphql_fields_for('epic_lists'.classify), include_pagination_info: true, args: params)}
+        }
+      BOARDS
+    )
+  end
+
+  before do
+    stub_licensed_features(epics: true)
+  end
+
+  context 'when the user does not have access to the epic board group' do
+    it 'returns nil group' do
+      post_graphql(pagination_query, current_user: current_user)
+
+      expect(graphql_data['group']).to be_nil
+    end
+  end
+
+  context 'when user can access the epic board group' do
+    before do
+      group.add_developer(current_user)
+    end
+
+    describe 'sorting and pagination' do
+      let(:data_path) { [:group, :epicBoard, :lists] }
+      let(:expected_results) { [list3.to_global_id.to_s, list1.to_global_id.to_s, list2.to_global_id.to_s] }
+
+      def pagination_results_data(nodes)
+        nodes.map { |list| list['id'] }
+      end
+
+      it_behaves_like 'sorted paginated query' do
+        # currently we don't support custom sorting for epic lists,
+        # nil value will be ignored by ::Graphql::Arguments
+        let(:sort_param) { nil }
+        let(:first_param) { 2 }
+      end
+    end
+  end
+end

spec/lib/gitlab/import_export/all_models.yml

@@ -87,6 +87,7 @@ label:
 - merge_requests
 - priorities
 - epic_board_labels
+- epic_lists
 milestone:
 - group
 - project