RSpec - use test double as block argument

Question

I have some Ruby code which looks like this:

Something.create do |x|
    x.foo = bar
end 

I'd like to write a test which uses a double in place of the block argument x, so that I can then call:

x_double.should_receive(:foo).with("whatever").

Is this possible?

Answer 1

 specify 'something' do
   x = double
   x.should_receive(:foo=).with("whatever")
   Something.should_receive(:create).and_yield(x)
   # call the relevant method
 end