rspec users - Aug 2008 - Stubbing calls to the command line

I''m using a call to wget to download a large datafile (multiple
megabytes) having assumed this will be quicker than using open-uri.

How can I spec the behaviour? Ideally I''d also like to not be hitting
the internet every time I test!

in my_object_spec.rb

  describe ".get_data" do
    before(:each) do
      @my_obj = MyObject.create(@valid_attributes)
    end
    it "should download the file" do
      # behaviour goes here
    end
  end


in my_object.rb:

  def get_data
      `wget --output-document=#{self.filename} #{self.file_uri}`
  end

I''ll be massively grateful for any help anyone can give me.
-- 
Posted via http://www.ruby-forum.com/.

On Aug 14, 2008, at 3:42 AM, Andy Croll wrote:
> I''m using a call to wget to download a large datafile (multiple
> megabytes) having assumed this will be quicker than using open-uri.
>
> How can I spec the behaviour? Ideally I''d also like to not be
hitting
> the internet every time I test!
>
> in my_object_spec.rb
>
>  describe ".get_data" do
>    before(:each) do
>      @my_obj = MyObject.create(@valid_attributes)
>    end
>    it "should download the file" do
>      # behaviour goes here
>    end
>  end
>
>
> in my_object.rb:
>
>  def get_data
>      `wget --output-document=#{self.filename} #{self.file_uri}`
>  end
Use Kernel.stub!(:`, "wget..."), and use Kernel.send(:`,
"wget")
instead of literal backticks.

Scott

On Thu, Aug 14, 2008 at 3:42 AM, Andy Croll <lists at ruby-forum.com>
wrote:
> I''m using a call to wget to download a large datafile (multiple
> megabytes) having assumed this will be quicker than using open-uri.
>
> How can I spec the behaviour? Ideally I''d also like to not be
hitting
> the internet every time I test!
>
> in my_object_spec.rb
>
>  describe ".get_data" do
>    before(:each) do
>      @my_obj = MyObject.create(@valid_attributes)
>    end
>    it "should download the file" do
>      # behaviour goes here
>    end
>  end
>
>
> in my_object.rb:
>
>  def get_data
>      `wget --output-document=#{self.filename} #{self.file_uri}`
>  end
>
> I''ll be massively grateful for any help anyone can give me.
I might end up with a separate object which managed making the wget
system call, and then I''ve have an integration-style test which
ensured it correctly downloaded a given passed in URL.

class MyObject
   def get_data
       WGet.download("http://some/path")
   end
end

class WGet
   def download(url)
      `wget #{url}`
   end
end

And I probably wouldn''t have a spec for WGet. I might make the
integration-style test a story. Perhaps when it ran I''d start
script/server in test mode, and then copy over a dummy file and pull
it down from "http://localhost:3000/public/dummy".

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

Scott Taylor wrote:
> Use Kernel.stub!(:`, "wget..."), and use Kernel.send(:`,
"wget")
> instead of literal backticks.
Interestingly this doesn''t quite work, but I used the principle.

The Kernel module is mixed into Object so when you use `shellcommand... 
` you can intercept the call on the object itself.

So I was able to:

@my_obj.stub!(:`)   ...in the before block

and

@my_obj.should_receive(:`, "wget...")   ...in the test

and use the short form:

`wget... `   ...in the actual method.

Thanks for your help chaps.
-- 
Posted via http://www.ruby-forum.com/.

On Aug 14, 2008, at 11:58 PM, Andy Croll wrote:
> Scott Taylor wrote:
>> Use Kernel.stub!(:`, "wget..."), and use Kernel.send(:`,
"wget")
>> instead of literal backticks.

Oops.  Meant Kernel.stub!(:`).with("wget..").and_return "some
return
value".


>>
>
> Interestingly this doesn''t quite work, but I used the principle.
>
> The Kernel module is mixed into Object so when you use  
> `shellcommand...
> ` you can intercept the call on the object itself.
>
> So I was able to:
>
> @my_obj.stub!(:`)   ...in the before block
>
> and
>
> @my_obj.should_receive(:`, "wget...")   ...in the test
>
> and use the short form:
>
> `wget... `   ...in the actual method.
>
> Thanks for your help chaps.
> -- 
> Posted via http://www.ruby-forum.com/.
> _______________________________________________
> rspec-users mailing list
> rspec-users at rubyforge.org
> http://rubyforge.org/mailman/listinfo/rspec-users
>

Yeah - the top level should work, too:

main = self

main.should_receive(:`).with("wget...")

`wget...`

The downside is that you would need to pass around around your top  
level instance of object (what I''ve been calling "main"
here).

Scott

On Thu, Aug 14, 2008 at 5:09 PM, Zach Dennis <zach.dennis at gmail.com>
wrote:
> I might end up with a separate object which managed making the wget
> system call, and then I''ve have an integration-style test which
> ensured it correctly downloaded a given passed in URL.
+1