[rspec-users] Asserting on a yield

Matt Wynne matt at mattwynne.net
Wed Mar 7 20:32:19 UTC 2012


On 7 Mar 2012, at 18:16, David Chelimsky wrote:

> On Wed, Mar 7, 2012 at 11:56 AM, Matt Wynne <matt at mattwynne.net> wrote:
>> 
>> On 7 Mar 2012, at 11:39, Morten Møller Riis wrote:
>> 
>> On Mar 7, 2012, at 8:22 AM, Matt Wynne wrote:
>> 
>> 
>> Hi all,
>> 
>> I'm spec'ing a method that yields a value. Right now, I spec it like this:
>> 
>>     result = nil
>>     thing.do_stuff { |value| result = value }
>>     result.should == expected
>> 
>> This feels like too much ceremony. What I want to do is something more this:
>> 
>>    thing.do_stuff.should yield_value(expected)
>> 
>> Is there anything built into RSpec to let me do this? If not, how do other
>> people test yields?
>> 
>> cheers,
>> Matt
>> 
>> 
>> How about this?
>> 
>> thing.do_stuff(&:to_s).should == expected
>> 
>> 
>> Yes, that's a neat hack, but I'd prefer to be able to assert on the actual
>> yielded value, instead of the result of calling an arbitrary method on it.
> 
> thing.do_stuff(&:self) would be a bit less arbitrary :)

It would, but does it work?

I assumed it would too but here on my Ruby 1.9.2 it gives me a NoMethodError :(

cheers,
Matt

--
Freelance programmer & coach
Author, http://pragprog.com/book/hwcuc/the-cucumber-book
Founder, http://www.relishapp.com/
Twitter, https://twitter.com/mattwynne


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