I'm trying to mock a class method with rspec:

lib/db.rb

class Db
  def self.list(options)
    Db::Payload.list(options)
  end
end

lib/db/payload.rb

class Db::Payload
  def self.list(options={})
  end
end

In my spec, I'm trying to setup the expectation Db::Payload.list will be called when I call Db.list:

describe Db do
  before(:each) do
    @options = {}
    Db::Payload.should_receive(:list).with(@options)
  end

  it 'should build the LIST payload' do
    Db.list(@options)
  end
end

The problem is that I am always receiving the following error:

undefined method `should_receive' for Db::Payload:Class

Any help understanding this error would be most appreciated :-)