RSpec should_receive macro that includes id of what needs to be tested

Question

How can I write this so it passes without hardcoding 1 . Chicken and the egg.

@sender = Factory(:user)
@receiver = Factory(:user)

mailer = double
mailer.should_receive(:deliver)
Mailer.should_receive(:email).with(1, @sender.id, @receiver.id).and_return(mailer)

# This will create an object with id #1 to make this test pass
@object = Object.create(:sender => @sender, :receiver => @receiver)

Answer 1

这个怎么样？

Mailer.should_receive(:email).with(an_instance_of(Fixnum), @sender.id, @receiver.id).and_return(mailer)