mocking stub chains with an assertion if the final call is made

rspec_stub_chain_if_spec.rb

# mocking stub chains with an assertion if the final call is made
# check https://github.com/rspec/rspec-mocks/issues/133 and 
# https://groups.google.com/d/topic/rspec/Dc98rP-3IFM/discussion

require 'rspec'

class DevOps
  attr_reader :monitor
  
  def initialize
    @monitor = Monitor.new
  end
  
  def check
    monitor.ping('DS1')
  end

  def noop
  end
end

class Monitor
  def ping(name)
    "pong #{name}"
  end
end

describe DevOps do
  let(:devops) { DevOps.new }
  
  it "#monitor called", :wip => true do
    monitor = devops.monitor
    # TODO: does not work
    devops.stub(:monitor) do
      monitor.should_receive(:ping).with('DS1').and_return(stub.as_null_object)
    end
    devops.check
  end

  it "#monitor not called" do
    # TODO: at_least(0) does not work
    # NOTE: wrong syntax. but this api for stub feels more natural to me
    devops.stub(:monitor) do |x|
      x.should_receive(:ping).with('DS1').and_return(stub.as_null_object)
    end
    devops.noop
  end
end

__END__

Am using ruby 1.9.3p194 (2012-04-20 revision 35410) [x86_64-darwin10.8.0]
and rspec 2.11.0

> rspec spec/bar_spec.rb 

DevOps
  #monitor called (FAILED - 1)
  #monitor not called

Failures:

  1) DevOps#monitor called
     Failure/Error: monitor.ping('DS1')
     NoMethodError:
       undefined method `ping' for #<Proc:0x00000101a6d630>
     # ./spec/bar_spec.rb:12:in `check'
     # ./spec/bar_spec.rb:34:in `block (2 levels) in <top (required)>'

Finished in 0.00128 seconds
2 examples, 1 failure

Failed examples:

rspec ./spec/bar_spec.rb:28 # DevOps#monitor called