Is it possible (or even recommended) to mock a Ruby require statement in ChefSpec?

Question

I've been writing ChefSpec unit test suites for the past couple of weeks and have managed to do quite a bit with it, but I have found a scenario that got me stumped. I have a recipe that includes the 'aws' cookbook's default recipe, which in turn installs the right_aws and then proceeds to require it.

But the ChefSpec runner seems to have problems with it, spitting out a Ruby LoadError:

LoadError
---------
cannot load such file -- right_aws

Cookbook Trace:
---------------
  /var/folders/0r/cg1hmpkj2nb3wh6slrg1hkhm0000gn/T/d20140612-36208-q1ecjj/cookbooks/aws/recipes/default.rb:25:in `from_file'
  /var/folders/0r/cg1hmpkj2nb3wh6slrg1hkhm0000gn/T/d20140612-36208-q1ecjj/cookbooks/acmecorp-postgresql/recipes/server.rb:71:in `from_file'

Relevant File Content:
----------------------
/var/folders/0r/cg1hmpkj2nb3wh6slrg1hkhm0000gn/T/d20140612-36208-q1ecjj/cookbooks/aws/recipes/default.rb:

 18:  #
 19:  
 20:  chef_gem "right_aws" do
 21:    version node['aws']['right_aws_version']
 22:    action :install
 23:  end
 24:  
 25>> require 'right_aws'
 26:  

Is there a way to mock that require 'right_aws' line from the 'aws' cookbook in my test? Is it recommended? Is it better to simply install the right_aws gem on the system running ChefSpec tests?

Answer 1

You have a few options:

1. You can ensure right_aws is available by installing it directly on your machine or with a Gemfile (as noted in the question comments)

2. You can mock the call to include_recipe directly (if you don't need the included recipe for your test)

   allow_any_instance_of(Chef::Recipe).to receive(:include_recipe)
   allow_any_instance_of(Chef::Recipe).to receive(:include_recipe).with('aws').and_return(true)
   

3. Mock the requires call itself.

   allow(Kernel).to receive(:require) 
   allow(Kernel).to receive(:require).with("right_aws").and_return(true)
   

If possible, I'd recommend #2