How To Disable an Observer in Rails

I wanted to disable an ActiveRecord::Observer during a migration in my Rails application. For the record, simply:

Payment.delete_observers

Update: October 17, 2009

The previous code is problematic, it will disable the PaymentObserver for the entire test run.

I've now switched to the following technique:

class OrderTest < ActiveSupport::TestCase
  include FlexMock::TestCase

  context "with observers disabled" do
    setup do
      # Disable order updates made by PaymentObserver
      flexmock(PaymentObserver.instance, :after_create => true)
    end

    context "...more tests..." do
    end
  end
end

You can adapt to whatever mocking framework you're using. You simply mock any methods in your observer class that you don't want called.