testing initialize or not

service_object_spec.rb

RSpec.describe CreateInvoice, type: :service do
  describe "#initialize" do
    context "when CreateInvoice is instantiated " do
      fixtures :users

      let(:user) { users(:customer_with_read) }

      let(:valid_params) do
        {
          "invoice_date(3i)" => "13",
          "invoice_date(2i)" => "1",
          "invoice_date(1i)" => "2018",
          "price_per_kwh" => "3.3"
        }
      end

      let(:invoice_creator) do
        CreateInvoice.new(user: user, params: valid_params)
      end

      it "has a user" do
        expect(invoice_creator.user).to eq(user)
      end