Dlaczego podczas uruchamiania narzędzia Rspec pojawia się niezdefiniowany błąd metody „mają”?

require 'spec_helper'describe Invoice do before :each do

 @user = FactoryGirl.create(:activated_user)

 person = FactoryGirl.create(:person, :user => @user, :company => nil)

 @project = FactoryGirl.create(:project, :user => @user, :person_ids => [person.id], :invoice_recipient_id => person.id)

 end it "has a valid factory" do

 expect(FactoryGirl.build(:invoice, :project => @project, :user => @user)).to be_valid

 end it "is invalid without a number" do

 expect(FactoryGirl.build(:invoice, :project => @project, :user => @user, :number => nil)).to have(1).errors_on(:number)

 endend

Failure/Error: expect(FactoryGirl.build(:invoice, :project => @project, :user => @user, :number => nil)).to have(1).errors_on(:number)

NoMethodError:

undefined method `have' for #<RSpec::ExampleGroups::Invoice_2:0x009ge29360d910>

# ./spec/models/invoice_spec.rb:16:in `block (2 levels) in <top (required)>'

have