[rspec-users] Surprising mock behavior

Mark Thomson mark.thomson at ieee.org
Sun Oct 19 00:56:32 EDT 2008

Stephen Eley wrote:
> On Sat, Oct 18, 2008 at 9:49 PM, Mark Thomson <mark.thomson at ieee.org> wrote:
>> [...]  What I've observed is that it behaves differently
>> if I include a "should_not_receive('...')" expectation somewhere in the
>> spec. In that case it seems that I can have as many "file.puts()" in the
>> component being tested as I like without specifying expectations for them,
>> and they pass just fine.
> Hmm, that does seem weird.  ... Maybe file a Lighthouse ticket with code samples
> clearly showing failing and passing tests.
Will do.

>   It's not the presence of a
> single should_receive that makes the mock want to know about every
> message it gets.  It's the fact that *it's a mock.*  Unless you tell
> them otherwise, that's just the way mocks work.  

Thanks, I think that's really the key concept I've been missing. I see 
how that changes the perspective on should_receive.

> If you don't want to
> have to specify everything, then that's what stubs are for.

I think I understand your point here, though am I right that a stub is 
restricted to specifying only one response to any particular method? You 
can't specify parameters in the way you do using :with in should_receive 
on a mock.  OTOH taking a different tack, it seems from the 
documentation (http://rspec.info/documentation/mocks/) that the 
:null_object option to mock() may allow you to leave some messages 
unspecified. I'll check on this.

>> In view of this, I wonder if a better way to formulate this test
>> might be to say something like -
>> object.should_receive :method => :method_name, :with_each_of => [arg1,
>> arg2,... argN]
> That's not a bad idea, but I suspect your tests in which you're
> calling 'puts' over and over might be a bit of an edge case.  

Yeah, I think that's true. I was actually trying to debug the spec, 
rather than object being tested. Still, it has turned out to be a useful 
learning exercise.

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