Fix update/create board mutation for iteration_cadence_id param

We were not handling iteration_cadence_id GlobalID properly on
both create and update mutations

ee/app/graphql/mutations/boards/scoped_board_mutation.rb

@@ -47,6 +47,15 @@ module Mutations
           args[:milestone_id] = args[:milestone_id].model_id
         end
 
+        if args[:iteration_cadence_id]
+          # TODO: remove this line when the compatibility layer is removed
+          # See: https://gitlab.com/gitlab-org/gitlab/-/issues/257883
+          args[:iteration_cadence_id] = ::Types::GlobalIDType[::Iterations::Cadence].coerce_isolated_input(
+            args[:iteration_cadence_id]
+          )
+          args[:iteration_cadence_id] = args[:iteration_cadence_id].model_id
+        end
+
         args[:label_ids] &&= args[:label_ids].map do |label_id|
           ::GitlabSchema.parse_gid(label_id, expected_type: ::Label).model_id
         end

ee/spec/graphql/mutations/boards/update_spec.rb

@@ -9,6 +9,7 @@ RSpec.describe Mutations::Boards::Update do
   let_it_be(:board) { create(:board, project: project) }
   let_it_be(:milestone) { create(:milestone, project: project) }
   let_it_be(:iteration) { create(:iteration, group: group) }
+  let_it_be(:iteration_cadence) { iteration.iterations_cadence }
   let_it_be(:label1) { create(:label, project: project) }
   let_it_be(:label2) { create(:label, project: project) }
 
@@ -83,6 +84,25 @@ RSpec.describe Mutations::Boards::Update do
         end
       end
 
+      # Needs be tested separately from updating iteration as that one will also update
+      # cadence_id to the iteration's cadence_id
+      context 'when updating only iteration_cadence' do
+        let(:mutation_params) do
+          {
+            id: board.to_global_id,
+            iteration_cadence_id: iteration_cadence.to_global_id
+          }
+        end
+
+        it 'updates iteration cadence' do
+          expect do
+            subject
+
+            board.reload
+          end.to change(board, :iteration_cadence).from(nil).to(iteration_cadence)
+        end
+      end
+
       context 'when passing labels param' do
         before do
           mutation_params.delete(:label_ids)

ee/spec/requests/api/graphql/mutations/boards/create_spec.rb

@@ -3,15 +3,43 @@
 require 'spec_helper'
 
 RSpec.describe Mutations::Boards::Create do
+  include GraphqlHelpers
+
+  let_it_be(:current_user, reload: true) { create(:user) }
   let_it_be(:parent) { create(:group) }
+  let_it_be(:iteration_cadence) { create(:iterations_cadence, group: parent) }
 
   let(:group_path) { parent.full_path }
+  let(:name) { 'board name' }
   let(:params) do
     {
       group_path: group_path,
-      name: name
+      name: name,
+      iteration_cadence_id: iteration_cadence.to_global_id.to_s
     }
   end
 
+  let(:mutation) { graphql_mutation(:create_board, params) }
+
+  subject { post_graphql_mutation(mutation, current_user: current_user) }
+
+  def mutation_response
+    graphql_mutation_response(:create_board)
+  end
+
   it_behaves_like 'boards create mutation'
+
+  context 'when the user has permission to create a board' do
+    before do
+      parent.add_maintainer(current_user)
+    end
+
+    it 'sets cadence_id on creation' do
+      expect { subject }.to change(::Board, :count).by(1)
+
+      created_board = ::Board.last
+
+      expect(created_board.iteration_cadence).to eq(iteration_cadence)
+    end
+  end
 end

spec/requests/api/graphql/mutations/boards/create_spec.rb

@@ -4,6 +4,16 @@ require 'spec_helper'
 
 RSpec.describe Mutations::Boards::Create do
   let_it_be(:parent) { create(:project) }
+  let_it_be(:current_user, reload: true) { create(:user) }
+
+  let(:name) { 'board name' }
+  let(:mutation) { graphql_mutation(:create_board, params) }
+
+  subject { post_graphql_mutation(mutation, current_user: current_user) }
+
+  def mutation_response
+    graphql_mutation_response(:create_board)
+  end
 
   let(:project_path) { parent.full_path }
   let(:params) do

spec/support/shared_examples/graphql/mutations/boards_create_shared_examples.rb

@@ -3,16 +3,6 @@
 RSpec.shared_examples 'boards create mutation' do
   include GraphqlHelpers
 
-  let_it_be(:current_user, reload: true) { create(:user) }
-  let(:name) { 'board name' }
-  let(:mutation) { graphql_mutation(:create_board, params) }
-
-  subject { post_graphql_mutation(mutation, current_user: current_user) }
-
-  def mutation_response
-    graphql_mutation_response(:create_board)
-  end
-
   context 'when the user does not have permission' do
     it_behaves_like 'a mutation that returns a top-level access error'