rspec users - Mar 2008 - How do you mock an object that you don''t have access to?

Hi,

How can I mock the "go" method of class B so that it returns the
string "fudge" in this situation?

class A
private
  def start
    @b = B.new
  end
end

class B
  def go
    puts "This is fun."
  end
end

Also, is it possible to do the mocha-like any_instance thing with RSpec?

Thank you,
David :)

On Fri, Mar 28, 2008 at 3:25 PM, David Beckwith <dbitsolutions at
gmail.com> wrote:
> Hi,
>
>  How can I mock the "go" method of class B so that it returns the
>  string "fudge" in this situation?
>
>  class A
>  private
>   def start
>     @b = B.new
>   end
>  end
>
>  class B
>   def go
>     puts "This is fun."
>   end
>  end
>
What about:

mock_b = mock(B)
mock_b.stub!(:go).and_return(true)

B.stub!(:new).and_return(mock_b)

Something like that?

-- 
Luis Lavena
Multimedia systems
-
Human beings, who are almost unique in having the ability to learn from
the experience of others, are also remarkable for their apparent
disinclination to do so.
Douglas Adams

On Fri, Mar 28, 2008 at 11:32 AM, Luis Lavena <luislavena at gmail.com>
wrote:
> On Fri, Mar 28, 2008 at 3:25 PM, David Beckwith <dbitsolutions at
gmail.com> wrote:
>  > Hi,
>  >
>  >  How can I mock the "go" method of class B so that it
returns the
>  >  string "fudge" in this situation?
>  >
>  >  class A
>  >  private
>  >   def start
>  >     @b = B.new
>  >   end
>  >  end
>  >
>  >  class B
>  >   def go
>  >     puts "This is fun."
>  >   end
>  >  end
>  >
>
>  What about:
>
>  mock_b = mock(B)
>  mock_b.stub!(:go).and_return(true)
>
>  B.stub!(:new).and_return(mock_b)
>
>  Something like that?
Stubbing the #new method on the class is one way to do it, as Luis mentioned.

Another approach is to pass the object in through the constructor.
Doing so will help you achieve looser coupling between the classes.

Pat

On Fri, Mar 28, 2008 at 8:12 PM, Pat Maddox <pergesu at gmail.com>
wrote:
> On Fri, Mar 28, 2008 at 11:32 AM, Luis Lavena <luislavena at
gmail.com> wrote:
>  > On Fri, Mar 28, 2008 at 3:25 PM, David Beckwith <dbitsolutions at
gmail.com> wrote:
>  >  > Hi,
>  >  >
>  >  >  How can I mock the "go" method of class B so that it
returns the
>  >  >  string "fudge" in this situation?
>  >  >
>  >  >  class A
>  >  >  private
>  >  >   def start
>  >  >     @b = B.new
>  >  >   end
>  >  >  end
>  >  >
>  >  >  class B
>  >  >   def go
>  >  >     puts "This is fun."
>  >  >   end
>  >  >  end
>  >  >
>  >
>  >  What about:
>  >
>  >  mock_b = mock(B)
>  >  mock_b.stub!(:go).and_return(true)
>  >
>  >  B.stub!(:new).and_return(mock_b)
>  >
>  >  Something like that?
>
>  Stubbing the #new method on the class is one way to do it, as Luis
mentioned.
>
>  Another approach is to pass the object in through the constructor.
>  Doing so will help you achieve looser coupling between the classes.
>
AKA Dependency Injection (http://martinfowler.com/articles/injection.html)

Aslak
>  Pat
>
>
> _______________________________________________
>  rspec-users mailing list
>  rspec-users at rubyforge.org
>  http://rubyforge.org/mailman/listinfo/rspec-users
>

http://atomicobjectrb.rubyforge.org/injection/

Zach

On Fri, Mar 28, 2008 at 2:17 PM, aslak hellesoy
<aslak.hellesoy at gmail.com> wrote:
>
> On Fri, Mar 28, 2008 at 8:12 PM, Pat Maddox <pergesu at gmail.com>
wrote:
>  > On Fri, Mar 28, 2008 at 11:32 AM, Luis Lavena <luislavena at
gmail.com> wrote:
>  >  > On Fri, Mar 28, 2008 at 3:25 PM, David Beckwith
<dbitsolutions at gmail.com> wrote:
>  >  >  > Hi,
>  >  >  >
>  >  >  >  How can I mock the "go" method of class B so
that it returns the
>  >  >  >  string "fudge" in this situation?
>  >  >  >
>  >  >  >  class A
>  >  >  >  private
>  >  >  >   def start
>  >  >  >     @b = B.new
>  >  >  >   end
>  >  >  >  end
>  >  >  >
>  >  >  >  class B
>  >  >  >   def go
>  >  >  >     puts "This is fun."
>  >  >  >   end
>  >  >  >  end
>  >  >  >
>  >  >
>  >  >  What about:
>  >  >
>  >  >  mock_b = mock(B)
>  >  >  mock_b.stub!(:go).and_return(true)
>  >  >
>  >  >  B.stub!(:new).and_return(mock_b)
>  >  >
>  >  >  Something like that?
>  >
>  >  Stubbing the #new method on the class is one way to do it, as Luis
mentioned.
>  >
>  >  Another approach is to pass the object in through the constructor.
>  >  Doing so will help you achieve looser coupling between the classes.
>  >
>
>  AKA Dependency Injection (http://martinfowler.com/articles/injection.html)
>
>  Aslak
>
>
>
>  >  Pat
>  >
>  >
>  > _______________________________________________
>  >  rspec-users mailing list
>  >  rspec-users at rubyforge.org
>  >  http://rubyforge.org/mailman/listinfo/rspec-users
>  >
>  _______________________________________________
>  rspec-users mailing list
>  rspec-users at rubyforge.org
>  http://rubyforge.org/mailman/listinfo/rspec-users
>


-- 
Zach Dennis
http://www.continuousthinking.com

Awesome.  Thank you.

David :)


On Fri, Mar 28, 2008 at 11:32 AM, Luis Lavena <luislavena at gmail.com>
wrote:
> On Fri, Mar 28, 2008 at 3:25 PM, David Beckwith <dbitsolutions at
gmail.com> wrote:
>  > Hi,
>  >
>  >  How can I mock the "go" method of class B so that it
returns the
>  >  string "fudge" in this situation?
>  >
>  >  class A
>  >  private
>  >   def start
>  >     @b = B.new
>  >   end
>  >  end
>  >
>  >  class B
>  >   def go
>  >     puts "This is fun."
>  >   end
>  >  end
>  >
>
>  What about:
>
>  mock_b = mock(B)
>  mock_b.stub!(:go).and_return(true)
>
>  B.stub!(:new).and_return(mock_b)
>
>  Something like that?
>
>  --
>  Luis Lavena
>  Multimedia systems
>  -
>  Human beings, who are almost unique in having the ability to learn from
>  the experience of others, are also remarkable for their apparent
>  disinclination to do so.
>  Douglas Adams
>  _______________________________________________
>  rspec-users mailing list
>  rspec-users at rubyforge.org
>  http://rubyforge.org/mailman/listinfo/rspec-users
>


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