From: Brian Candler <b.candler@...>
Date: 2010-05-11T20:13:35+09:00
Subject: Re: Unit Test of method calling system() - how?

Martin Hansen wrote:
> @Brian
> 
> I have been looking at flexmock

I used to use flexmock, but switched to mocha. The error messages were 
much more informative, especially in terms of expectations not met or 
unexpected invocations.

> but I guess the mocking method is not 
> important - it is how?!? ... Especially since these are private methods.

Sorry, I don't understand you're trying to say there.

'system' is a private method inherited from Kernel, but you can happily 
mock or stub it within a test.

If you know the appropriate object instance, then

   obj.expects(:system)....

is fine. If you don't, but you know what class it is, then

   Foo.any_instance.expects(:system)....

Unfortunately, Object.any_instance. doesn't do the trick.

> Perhaps the code should be rearranged?

That's another option - for example, make print_wiki a method, which you 
can mock out.

Or you could check for the required side-effects of print_wiki, by 
running the test inside IO.popen, and checking the text written. This 
will be slower, because you're actually running the external print_wiki 
command.

class Foo
  def bar
    system("cat /etc/motd")
  end
end

require 'test/unit'
require 'mocha'
class TestFoo < Test::Unit::TestCase
  def test_foo
    IO.popen("-") do |child|
      if child
        assert_match /Linux/, child.read
      else
        a = Foo.new
        a.bar
      end
    end
  end
end
-- 
Posted via http://www.ruby-forum.com/.