Why does RSpec break on create method tests?

Question

Ruby on Rails

Good afternoon. There are integration tests on RSpec. When running tests, it displays the following message:

Failure/Error: ActionCable.server.broadcast "boards_channel_#{list_params[:board_id]}", serialized_data
SocketError:
       getaddrinfo: Name does not resolve

It breaks only when testing create methods.
Below is an example:

#create

def create
      @list = List.new(list_params)

      @board = Board.find(list_params[:board_id])

      if @list.save
        serialized_data = ActiveModelSerializers::Adapter::Json.new(
          ListSerializer.new(@list)
        ).serializable_hash
        ActionCable.server.broadcast "boards_channel_#{list_params[:board_id]}", serialized_data
        render json: @list.to_json, status: :ok
      end
    end

rspec

it "create" do
    params = {
      title: "Sample list",
      board_id: board.id
    }

    post api_v1_lists_path(list: params)

    expect(response).to have_http_status(:ok)
  end

Factory

FactoryBot.define do
  factory :list do
    title { FFaker::Skill.specialty }
    board

    trait :within_board do
      association :board
    end

    trait :with_cards do
      after :create do |list|
        cards = create_list :card, rand(0..5), list: list
      end
    end
  end
end

What is the problem?