GraphQL expose issues under board list

- Add test

app/graphql/resolvers/board_list_issues_resolver.rb

+# frozen_string_literal: true
+
+module Resolvers
+  class BoardListIssuesResolver < BaseResolver
+    type Types::IssueType, null: true
+
+    alias_method :list, :object
+
+    def resolve(**args)
+      # rubocop: disable CodeReuse/ActiveRecord
+      service = Boards::Issues::ListService.new(list.board.resource_parent, context[:current_user], { board_id: list.board.id, id: list.id })
+      service.execute.reorder("relative_position ASC")
+      # rubocop: enable CodeReuse/ActiveRecord
+    end
+  end
+end

app/graphql/types/board_list_type.rb

@@ -19,6 +19,10 @@ module Types
     field :collapsed, GraphQL::BOOLEAN_TYPE, null: true,
           description: 'Indicates if list is collapsed for this user',
           resolve: -> (list, _args, ctx) { list.collapsed?(ctx[:current_user]) }
+
+    field :issues, ::Types::IssueType.connection_type, null: true,
+          description: 'Board issues',
+          resolver: ::Resolvers::BoardListIssuesResolver
   end
   # rubocop: enable Graphql/AuthorizeTypes
 end

doc/api/graphql/reference/gitlab_schema.graphql

@@ -1087,6 +1087,31 @@ type BoardList {
   """
   id: ID!
 
+  """
+  Board issues
+  """
+  issues(
+    """
+    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
+  ): IssueConnection
+
   """
   Label of the list
   """

doc/api/graphql/reference/gitlab_schema.json

@@ -2927,6 +2927,59 @@
               "isDeprecated": false,
               "deprecationReason": null
             },
+            {
+              "name": "issues",
+              "description": "Board issues",
+              "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": "IssueConnection",
+                "ofType": null
+              },
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
             {
               "name": "label",
               "description": "Label of the list",

spec/graphql/types/board_list_type_spec.rb

@@ -6,7 +6,7 @@ RSpec.describe GitlabSchema.types['BoardList'] do
   specify { expect(described_class.graphql_name).to eq('BoardList') }
 
   it 'has specific fields' do
-    expected_fields = %w[id list_type position label]
+    expected_fields = %w[id list_type position label issues]
 
     expect(described_class).to include_graphql_fields(*expected_fields)
   end