email_sender_controller_spec.rb

RSpec.describe Spree::EmailSenderController, type: :controller do
  let!(:product) { create(:product) }

  before do
    allow(controller).to receive(:spree_current_user) { nil }
  end

  context '#send_mail' do
    # can be different types but no clue what they can be except from product
    specify do
      spree_get :send_mail, type: 'product', id: product.id
      expect(response).to be_success
    end
  end
end