From aaron at tenderlovemaking.com  Thu Mar 20 15:55:08 2008
From: aaron at tenderlovemaking.com (Aaron Patterson)
Date: Thu, 20 Mar 2008 12:55:08 -0700
Subject: [Flexmock-users] mocking methods called from initialize
Message-ID: <20080320195508.GA30023@mac-mini.lan>

Hi,

When mocking new instances of an object, when does flexmock override the
mocked methods?  I'm not sure how to ask this question without an
example:

  class Foo
    def initialize; two; end
    def two; puts "hello"; end
  end
  
  class TestFoo < Test::Unit::TestCase
    def test_call_two
      flexmock(Foo).new_instances.should_receive(:two).and_return(10)
      Foo.new
    end
  end

When I wrote that, I expected two() to return 10 like the mock says.
But I see "hello" printed when I run the test.  Are my expectations
incorrect?  If so, how can I mock the "two" method?

Thanks!

-- 
Aaron Patterson
http://tenderlovemaking.com/

From pm at ubit.com  Fri Mar 21 05:21:17 2008
From: pm at ubit.com (Paul McMahon)
Date: Fri, 21 Mar 2008 18:21:17 +0900
Subject: [Flexmock-users] mocking methods called from initialize
In-Reply-To: <20080320195508.GA30023@mac-mini.lan>
References: <20080320195508.GA30023@mac-mini.lan>
Message-ID: <47E37E0D.1070906@ubit.com>

Aaron Patterson wrote:
 > Hi,
 >
 > When mocking new instances of an object, when does flexmock override the
 > mocked methods?  I'm not sure how to ask this question without an
 > example:
 >
 >   class Foo
 >     def initialize; two; end
 >     def two; puts "hello"; end
 >   end
 >
 >   class TestFoo < Test::Unit::TestCase
 >     def test_call_two
 >       flexmock(Foo).new_instances.should_receive(:two).and_return(10)
 >       Foo.new
 >     end
 >   end
 >
 > When I wrote that, I expected two() to return 10 like the mock says.
 > But I see "hello" printed when I run the test.  Are my expectations
 > incorrect?  If so, how can I mock the "two" method?
 >
 > Thanks!
 >

new_instances calls the original new method on the specified object, and 
creates a mock object out of the result of that call.  As such, you 
cannot mock a method called in the initialize method of an object.  If 
you are really set on mocking a method called in initialize, you could 
do something like:

Foo.class_eval { def foo; 2; end }

but, you should probably be listening to what this test case is telling 
you: that something smells.  I normally avoid mocking any instance 
methods on the object I'm testing.  If you need to mock an instance 
method, it is probably because you should split the object you are 
testing into multiple objects.  You might consider refactoring your code 
to something like this:

class Bar
   def two; puts "hello"; end
end

class Foo
   def initialize(bar); bar.two; end
end

class TestFoo < Test::Unit::TestCase
   def test_call_two
     mock_bar = flexmock.should_receive(:two).and_return(10).mock
     Foo.new(mock_bar)
   end
end