WorkItemUpdate mutation allows to update title

Mutation allows updating the title attribute
of a work item

app/graphql/mutations/work_items/update.rb

@@ -18,6 +18,9 @@ module Mutations
       argument :state_event, Types::WorkItems::StateEventEnum,
                description: 'Close or reopen a work item.',
                required: false
+      argument :title, GraphQL::Types::String,
+               required: false,
+               description: copy_field_description(Types::WorkItemType, :title)
 
       field :work_item, Types::WorkItemType,
             null: true,

doc/api/graphql/reference/index.md

@@ -5200,6 +5200,7 @@ Input type: `WorkItemUpdateInput`
 | <a id="mutationworkitemupdateclientmutationid"></a>`clientMutationId` | [`String`](#string) | A unique identifier for the client performing the mutation. |
 | <a id="mutationworkitemupdateid"></a>`id` | [`WorkItemID!`](#workitemid) | Global ID of the work item. |
 | <a id="mutationworkitemupdatestateevent"></a>`stateEvent` | [`WorkItemStateEvent`](#workitemstateevent) | Close or reopen a work item. |
+| <a id="mutationworkitemupdatetitle"></a>`title` | [`String`](#string) | Title of the work item. |
 
 #### Fields
 

spec/requests/api/graphql/mutations/work_items/update_spec.rb

@@ -10,7 +10,7 @@ RSpec.describe 'Update a work item' do
   let_it_be(:work_item, refind: true) { create(:work_item, project: project) }
 
   let(:work_item_event) { 'CLOSE' }
-  let(:input) { { 'stateEvent' => work_item_event } }
+  let(:input) { { 'stateEvent' => work_item_event, 'title' => 'updated title' } }
 
   let(:mutation) { graphql_mutation(:workItemUpdate, input.merge('id' => work_item.to_global_id.to_s)) }
 
@@ -26,15 +26,18 @@ RSpec.describe 'Update a work item' do
     let(:current_user) { developer }
 
     context 'when the work item is open' do
-      it 'closes the work item' do
+      it 'closes and updates the work item' do
         expect do
           post_graphql_mutation(mutation, current_user: current_user)
           work_item.reload
-        end.to change(work_item, :state).from('opened').to('closed')
+        end.to change(work_item, :state).from('opened').to('closed').and(
+          change(work_item, :title).from(work_item.title).to('updated title')
+        )
 
         expect(response).to have_gitlab_http_status(:success)
         expect(mutation_response['workItem']).to include(
-          'state' => 'CLOSED'
+          'state' => 'CLOSED',
+          'title' => 'updated title'
         )
       end
     end