[mocha-developer] Stubbing yielding methods

Duncan Beevers duncanbeevers at gmail.com
Fri Sep 21 16:30:28 EDT 2007

It's certainly necessary to test the code tucked away into these
blocks, but I feel like yielding is testing in the wrong direction.

Instead of yielding values or mocks into the block, perhaps we can
check metadata about the provided block (arity, required params) and
then test the functionality of the block explicitly.

class Test::Unit::TestCase
  def test_up_them_all
    upcasing_block = lambda { |e| e.upcase }

    list_of_words = [ 'socks', 'mittens', 'flashlight' ]

    u = Upperizer.new

    assert_equal 'HONK', upcasing_block('honk')

On 9/21/07, James Mead <jamesmead44 at gmail.com> wrote:
> I've just been tying my brain in knots looking at bug #8687 (
> http://rubyforge.org/tracker/index.php?func=detail&aid=8687&group_id=1917&atid=7477
> ).
> I've been (1) trying to work out whether there is anything logically wrong
> with Mocha's existing behaviour and (2) whether Mocha should support the
> requested functionality.
> It all centres around the use of the Expectation#yields method. I've put a
> couple of examples together to try and help me think about it. The first one
> (http://pastie.caboo.se/99412) is a simplified version of the example in the
> bug report using a block and stubbing a method that yields to that block.
> In the second example (http://pastie.caboo.se/99413) I tried to think about
> how it would work if I converted the block to a method on an object. I
> slightly ran out of steam on this one when I realised that in this case when
> I realised Executor#execute wouldn't be called because the implementation of
> Collaborator#yielding_method is stubbed.
> This made me wonder if the Expectation#yields method should exist at all! In
> particular, in the block example, it feels odd because you are going from
> real code (ClassUnderTest) into mock code (mocked version of Collaborator)
> and back into real code (the block itself). I wonder if this is really
> sensible and/or useful.
> Has anybody got any thoughts?
> Thanks.
> --
> James.
> http://blog.floehopper.org
> http://tumble.floehopper.org
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