title: Testing aasm state transitions with rspec
body: <p>I'm using aasm gem to handle state transitions in my project. I have a simple model that looks like this:</p>
  
  <pre><code>class TransferPostingBid &lt; ActiveRecord::Base
    include AASM
  
    aasm :status do
      state :offered, initial: true
      state :wait_for_pap_confirmation
      state :confirmed_by_pap
      state :retracted_by_pap
  
      event :pap_choosed do
        transitions from: :offered, to: :wait_for_pap_confirmation
      end
  
      event :confirmed_by_pap do
        transitions from: :wait_for_pap_confirmation, to: :confirmed_by_pap
      end
  
      event :retracted_by_pap do
        transitions from: :wait_for_pap_confirmation, to: :retracted_by_pap
      end
    end
  end
  </code></pre>
  
  <p>And I'm trying to test transitions with aasm built in rspec matchers:</p>
  
  <pre><code>require 'rails_helper'
  
  describe TransferPostingBid, type: :model do
    describe 'state transitions' do
      let(:transfer_posting_bid) { TransferPostingBid.new }
  
      it 'has default state' do
        expect(transfer_posting_bid).to transition_from(:offered).to(:wait_for_pap_confirmation).on_event(:pap_choosed)
      end
    end
  end
  </code></pre>
  
  <p>When I run this spec it returns me following error:</p>
  
  <pre><code> AASM::UnknownStateMachineError:
     There is no state machine with the name 'default' defined in TransferPostingBid!
  </code></pre>
  
  <p>How can I fix this?</p>