Testing private method in Ruby (rspec) [duplicate]

Question

Yes, I know, that testing private methods it's not a good idea (and I read this thread - http://www.ruby-forum.com/topic/197346 - and some others)

But how can I test the following code?

I use xmpp4r. In my public method #listen I start receive jabber messages like so:

def listen   @client.add_message_callback do |m|     do_things_with_message(m)   end end  private def do_things_with_message(m)   # end 

#add_message_callback - runs block, when message come (in different thread)

So, testing #listen method it's difficult and it more testing xmpp4r than my #do_things_with_message

How to do all right and test #do_things_with_message?:) (http://www.ruby-forum.com/topic/197346#859664)

Refactor private methods to a new object essentialy would be as I making them a public (and class with one method - it's senselessly

EDIT: This is more a theoretical question about clean code and the correct tests. In my first link people argue that the test private methods poorly. I don't want cheat with #send, but also I don't see any viable ways to refactor

Answer 1

You can call a private method in ruby using the send method. Something like this:

@my_object = MyObject.new @my_object.send(:do_things_with_message, some_message) 

In a test that would look something like:

it "should do a thing" do   my_object = MyObject.new   my_object.send(:do_things_with_message, some_message)   my_object.thing.should == true end 

Answer 2

Putting aside the question of whether or not you should be testing a private method, it is very possible in Ruby to temporarily make a private method public. Here is what I mean:

# Metaprogrammatical magic to temporarily expose # a Class' privates (methods). class Class   def publicize_methods     saved_private_instance_methods = self.private_instance_methods     self.class_eval { public *saved_private_instance_methods }     yield     self.class_eval { private *saved_private_instance_methods }   end end 

You would use publicize_methods like this:

ClassToTest.publicize_methods do   ...   do_private_things_with_message(m).should ???   ... end