Add specs for single board list request

Update GraphQL Schema

Update field description

- Update GraphQL schema

Add tests for ListService when passing list_id

app/graphql/resolvers/board_lists_resolver.rb

@@ -8,7 +8,7 @@ module Resolvers
 
     argument :id, GraphQL::ID_TYPE,
              required: false,
-             description: 'Find a list by its ID'
+             description: 'Find a list by its global ID'
 
     alias_method :board, :object
 
@@ -27,7 +27,12 @@ module Resolvers
     private
 
     def board_lists(id)
-      service = Boards::Lists::ListService.new(board.resource_parent, context[:current_user], list_id: extract_list_id(id))
+      service = Boards::Lists::ListService.new(
+        board.resource_parent,
+        context[:current_user],
+        list_id: extract_list_id(id)
+      )
+
       service.execute(board, create_default_lists: false)
     end
 

changelogs/unreleased/230903-graphql-fetch-single-list-under-board.yml

+---
+title: Add option to query a single board list with GraphQL API
+merge_request: 38216
+author:
+type: added

doc/api/graphql/reference/gitlab_schema.graphql

@@ -956,6 +956,11 @@ type Board {
     """
     first: Int
 
+    """
+    Find a list by its global ID
+    """
+    id: ID
+
     """
     Returns the last _n_ elements from the list.
     """

doc/api/graphql/reference/gitlab_schema.json

@@ -2508,6 +2508,16 @@
               "name": "lists",
               "description": "Lists of the board",
               "args": [
+                {
+                  "name": "id",
+                  "description": "Find a list by its global ID",
+                  "type": {
+                    "kind": "SCALAR",
+                    "name": "ID",
+                    "ofType": null
+                  },
+                  "defaultValue": null
+                },
                 {
                   "name": "after",
                   "description": "Returns the elements in the list that come after the specified cursor.",

spec/graphql/resolvers/board_lists_resolver_spec.rb

@@ -65,7 +65,7 @@ RSpec.describe Resolvers::BoardListsResolver do
           expect(list).to eq [label_list]
         end
 
-        it 'returns empty result if list is not accessible found' do
+        it 'returns empty result if list is not found' do
           external_group = create(:group, :private)
           external_board = create(:board, resource_parent: external_group )
           external_label = create(:group_label, group: group)
@@ -75,6 +75,11 @@ RSpec.describe Resolvers::BoardListsResolver do
 
           expect(list).to eq List.none
         end
+
+        it 'raises an argument error if list ID is not valid' do
+          expect { resolve_board_lists(args: { id: 'test' }).items }
+            .to raise_error(Gitlab::Graphql::Errors::ArgumentError)
+        end
       end
     end
   end

spec/requests/api/graphql/boards/board_lists_query_spec.rb

@@ -105,6 +105,20 @@ RSpec.describe 'get board lists' do
         end
       end
     end
+
+    context 'when querying for a single list' do
+      before do
+        board_parent.add_reporter(user)
+      end
+
+      it 'finds the correct list' do
+        label_list = create(:list, board: board, label: label, position: 10)
+
+        post_graphql(query("id: \"#{global_id_of(label_list)}\""), current_user: user)
+
+        expect(lists_data[0]['node']['title']).to eq label_list.title
+      end
+    end
   end
 
   describe 'for a project' do

spec/services/boards/lists/list_service_spec.rb

@@ -6,12 +6,14 @@ RSpec.describe Boards::Lists::ListService do
   let(:user) { create(:user) }
 
   describe '#execute' do
+    let(:service) { described_class.new(parent, user) }
+
     context 'when board parent is a project' do
       let(:project) { create(:project) }
       let(:board) { create(:board, project: project) }
       let(:label) { create(:label, project: project) }
       let!(:list) { create(:list, board: board, label: label) }
-      let(:service) { described_class.new(project, user) }
+      let(:parent) { project }
 
       it_behaves_like 'lists list service'
     end
@@ -21,7 +23,7 @@ RSpec.describe Boards::Lists::ListService do
       let(:board) { create(:board, group: group) }
       let(:label) { create(:group_label, group: group) }
       let!(:list) { create(:list, board: board, label: label) }
-      let(:service) { described_class.new(group, user) }
+      let(:parent) { group }
 
       it_behaves_like 'lists list service'
     end

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

@@ -26,4 +26,22 @@ RSpec.shared_examples 'lists list service' do
       expect(service.execute(board)).to eq [board.backlog_list, list, board.closed_list]
     end
   end
+
+  context 'when wanting a specific list' do
+    let!(:list1) { create(:list, board: board) }
+
+    it 'returns list specified by id' do
+      service = described_class.new(parent, user, list_id: list1.id)
+
+      expect(service.execute(board, create_default_lists: false)).to eq [list1]
+    end
+
+    it 'returns empty result when list is not found' do
+      external_board = create(:board, resource_parent: create(:project))
+      external_list = create(:list, board: external_board)
+      service = described_class.new(parent, user, list_id: external_list.id)
+
+      expect(service.execute(board, create_default_lists: false)).to eq(List.none)
+    end
+  end
 end