From: Nathaniel Talbott <nathaniel@...>
Date: 2003-08-02T18:13:55+09:00
Subject: Anonymous, single instance class creation

I find myself doing the following in tests a lot:

  some_external_object = Object.new
  def some_external_object.some_method
    ... do some stuff ...
  end

OR:

  some_external_object = Object.new
  class << some_external_object
    def some_method
      ... do some stuff ...
    end
  end

Is there a way to do that more concisely? Perhaps to eliminate the separate
Object.new?

Also, is there a way to let the methods be more like closures, i.e.:

  a = "stuff"

  some_external_object = Object.new
  def some_external_object.some_method
    a #from external scope
  end

  assert_equal(a, method_under_test(some_external_object))

That would make it even more powerful.

To explain why I care: I'm finding this technique to be clearer than using
an explicit mocking framework. It tends to help me keep the stubs simple,
and it makes it explicit in the test (or sometimes I pull it out in to
#setup) what's going on, as opposed to having to look at another class to
see everything that makes the test tick. There are definitely downsides, but
if there are good answers to the two questions above, perhaps not as many as
I thought.

Thanks!


Nathaniel

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