[mocha-developer] [Rails] Trying to Overide Class Object Methdos For Testing

[James Mead]

On 15/08/06, Steven Hansen <runner at berkeley.edu> wrote:
>
> I thought I had a handle on the whole singleton class thing but now I'm
> not too sure.
>
> I have a class definition:
>
> class ValidationMaster
>   def validate(params)
>     # complex and time consuming validation
>     # returns true on success, raises Exception
>     # on failure
>   end
> end
>
> Okay, so when I'm running my functional tests within rails, I want to be
> able to control how the validate(params) method behaves.
>
> So, I've created a ValidationMaster class definition and put it in
> RAILS_ROOT/test/mocks/test/validation_master.rb
>
> The methods I've defined there seem to be correctly overriding those of
> the original class definition.
>
> Now here is where I'm having problems.  Within certain functional tests,
> I want validate(params) to return true.  Other times
> I want it to fail and throw an exception.  Thus, I can't rely on the
> Mock ValidationMaster class definition to take care of this.
>
> But then I thought, HEY, within each test I can open up the singleton
> class for the ValidationMaster class object.  Whoo hoo,
> I'm in charge now!
>
> def test_stuff
>   class << ValidationMaster
>     def validate(params)
>       raise ValidationException
>     end
>   end
>
>   vm = ValidationMaster.new
>   vm.validate("Jeff")
> end
>
> But, when I run my test, the exception is not getting thrown.  The
> methods I've defined in the Mock are all working right, but it's somehow
> not seeing
> the override within test_stuff.  Am I mistaken here, can I not override
> the class definition of ValidationMaster like this?


I think this is what you want...

def test_stuff
  vm = ValidationMaster.new
  class << vm
    def validate(params)
      raise ValidationException
    end
  end

  vm.validate("Jeff")
end

However, you might want to consider using Mocha
<http://mocha.rubyforge.org>to write the test more concisely...

def test_stuff
  vm = ValidationMaster.new
  vm.stubs(:validate).raises(ValidationException)
  vm.validate("Jeff")
end

Hope that helps.
James.
http://blog.floehopper.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://rubyforge.org/pipermail/mocha-developer/attachments/20060815/5fd5ce9e/attachment.html