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