01-question.md

Suppose I have a third party lib that uses a DSL to perform its magic like the dsl.rb and runtime.rb files below. My application has a Consumer class that uses that API as shown in the consumer.rb file. How should I spec the say method to ensure the output method receives the correct parameter?

consumer.rb

require 'dsl'

class Consumer
  def say(message)
    DSL.execute do
      output message
    end
  end
end

dsl.rb

require 'runtime'

class DSL
  def self.execute(&block)
    Runtime.new(&block)
  end
end

runtime.rb

class Runtime
  def initialize(&block)
    self.instance_eval(&block)
  end

  def output(message)
    puts message
  end
end

Something like...

Runtime.any_instance.should_receive(:output).with("the message")

The problem I see in this approach is that I need to know how the API works internally. At least I need to know the execute method creates a Runtime instance. I'm not sure I should dig that deep...

Can you handle the ParamErrorMethod when you pass the param? If so, you can use the ParamError to spec, maybe

If you don't know deeply the API, you can handle only rescues.

I don't think so :/