rspec users - Aug 2009 - arbitrary handling of received messages in mocks

I am trying to process a message sent to a mock to verify it contains  
the correct keys. In my case I am sending a JSON string to the mock  
built from data passed in via the test. The object internally builds a  
hash and then constructs the JSON string from it.

I can''t get my mock to fail though. Here''s an example similar
to what
I''ve got.

describe Foo
   it "should match the json string" do
     # setup stubs & mocks
     ...
     hsh = ... # keys and values used inside the method
     @api.should_receive(:publish_to_bus) do |message|
       false # should always fail
     end

     Foo.new(@api).decode hsh
   end
end

The documentation says the expectation passes or fails based upon the  
return value of the block. I can''t even force it to fail by returning  
false. Once I figure this out, I plan to decode the JSON string in the  
mock block and compare the resulting collection with the data I  
originally passed in to the object. This behavior will likely become a  
helper method (if that matters).

What am I doing wrong?

rspec 1.2.8
ruby 1.8.6 patch 287, Windows
Running under Netbeans 6.7.1

Thank you for your help.

cr

Chuck Remes wrote:
> I am trying to process a message sent to a mock to verify it contains 
> the correct keys. In my case I am sending a JSON string to the mock 
> built from data passed in via the test. The object internally builds a 
> hash and then constructs the JSON string from it.
>
> I can''t get my mock to fail though. Here''s an example
similar to what
> I''ve got.
>
> describe Foo
>   it "should match the json string" do
>     # setup stubs & mocks
>     ...
>     hsh = ... # keys and values used inside the method
>     @api.should_receive(:publish_to_bus) do |message|
>       false # should always fail
>     end
>
>     Foo.new(@api).decode hsh
>   end
> end
>
> The documentation says the expectation passes or fails based upon the 
> return value of the block. I can''t even force it to fail by
returning
> false. Once I figure this out, I plan to decode the JSON string in the 
> mock block and compare the resulting collection with the data I 
> originally passed in to the object. This behavior will likely become a 
> helper method (if that matters).
The docs could wrong.. I dunno....  When using the block form I always 
set expectation within the block.  This may be the wrong way to use it, 
but it works.  Like so:

describe Foo
  it "should match the json string" do
    # setup stubs & mocks
    ...
    hsh = ... # keys and values used inside the method
    @api.should_receive(:publish_to_bus) do |message|
         JSON.parse(message).should == hsh # or whatever you need to do 
here.
    end

    Foo.new(@api).decode hsh
  end
end



-Ben

On 25 Aug 2009, at 20:59, Chuck Remes wrote:
> The documentation says the expectation passes or fails based upon  
> the return value of the block. I can''t even force it to fail by  
> returning false.
The docs (http://rspec.info/documentation/mocks/message_expectations.html 
) say:
> You can supply a block to a message expectation. When the message is  
> received
> by the mock, the block is passed any arguments and evaluated. The  
> result is
> the return value of the block.
This means that the mocked method will return the value that is  
returned by the block; by returning false in your block, you''re just  
arranging for the mocked method to return false. (So this is the same  
as @api.should_receive(:publish_to_bus).and_return(false).)

If you want the message expectation to fail, you need to put a failing  
expectation inside the block.

Cheers,
-Tom

On Aug 25, 2009, at 5:13 PM, Tom Stuart wrote:
> On 25 Aug 2009, at 20:59, Chuck Remes wrote:
>> The documentation says the expectation passes or fails based upon  
>> the return value of the block. I can''t even force it to fail
by
>> returning false.
>
> The docs (http://rspec.info/documentation/mocks/message_expectations.html 
> ) say:
>
>> You can supply a block to a message expectation. When the message  
>> is received
>> by the mock, the block is passed any arguments and evaluated. The  
>> result is
>> the return value of the block.
>
> This means that the mocked method will return the value that is  
> returned by the block; by returning false in your block, you''re
just
> arranging for the mocked method to return false. (So this is the  
> same as @api.should_receive(:publish_to_bus).and_return(false).)
>
> If you want the message expectation to fail, you need to put a  
> failing expectation inside the block.
Setting an expectation within the block makes it work. I think the  
docs should be clearer that the expectations inside are necessary.

cr