From: David Palm <dvdplm@...>
Date: 2009-07-06T20:25:58+09:00
Subject: How to test %x[] calls?

Hi all,
how can I set an expectation on an external command execution?

Code:
	def do_stuff(arg)
	  %x(external_executable_name #{arg})
	end

Test (not working):
	it "shells out and executes 'external_executable_name' with a bunch of nifty options" do
     	  Kernel.should_receive(:`).with("external_executable_name argy args")
	  @worker.do_stuff("argy args")
	end
	
If I change the code to:

	def do_stuff(arg)
	   Kernel.`(external_executable_name #{arg})
	end

...the test passes.

If I change the code to:

	def do_stuff(arg)
	   `(external_executable_name #{arg})`
	end

...the test fails.

Any other ideas? I could use Kernel#system() of course, but then I'd lose the output (or I'd have to go through the hoops of redirecting and reading etc, which I'd prefer to avoid). Why can't I test for the original %x?