How to access to test (devise) current_user in a helper?

I have used current_user in a helper as following:

module InvestorsHelper
  def single?
    binding.pry
    current_user.kyc.marital_status == 'Single'
  end

  def married?
    current_user.kyc.marital_status == 'Married'
  end

  def politically_exposed?
    current_user.kyc.is_politically_exposed.present?
  end

  def tax_residency?
    current_user.kyc.is_tax_residency.present?
  end
end

But how do I test those methods in rspec testing?

I wrote the following rspec code:

context "Investors Helper" do
    before(:each) do
      puts "Befpre exljfgd"
      current_user =    @user ||= FactoryGirl.create(:user)
      @kyc  ||= FactoryGirl.create(:kyc, user_id: @user.id)
    end

  describe InvestorsHelper, '#single?' do
    it 'returns status of current user' do

      result = InvestorsHelper.single?
      binding.pry
    end
end

end end

But it returns the error: NameError:

   undefined local variable or method `current_user' for InvestorsHelper:Module

What am I doing wrong?