Difference between recommended and suggested cookbooks

this one helps. If you are working with the web forms technology and want the ability to create a desktop application with the same code base I would suggest using the Model View Presenter pattern to break out the UI from the business coding. In addition to this approach, I would recommend creating a service layer that handles the logic beyond the Presenter class (including Data Access / Business Logic).
I found that creating a class library to hold this UI agnostic code makes it very easy to reuse this code. This architecture also lends itself to a simple web service transition if you take that route because your service inputs/outputs should be the same in your class library as they would be in a web service (WCF or ASMX)

I wish this help you PHP provides you with class_exists() for just that purpose. Check if the class is loaded with it - it will call the autoloader by default so no need to instantiate it with a try/catch block beforehand.
If you are trying to test for an extension by the way you can also use extension_loaded() or function_exists().

it fixes the issue You cannot "install" cookbooks directly to a Chef Server, they always have to come indirectly from a workstation. The usual flow is that you download them locally from Supermarket and the re-upload to your Chef Server. Tools like Berkshelf and the Chef Policyfile system handle the heavy lifting for you so you don't have to do it one-by-one.

will be helpful for those in need It seems that you have copied that line including typographic (?) quotes. Have a look at the output:

$ sudo chef-client -z --runlist "apache::server"

Does that help utilize the run_list in the role object. in your case, it should be something like:

$ cat roles/test.json
{
  "run_list": [
    "recipe[test-a]",
    "recipe[test-b]"
  ]
}

$ cat test/recipes/default.rb
include_recipe 'test-a'
include_recipe 'test-b'

$ cat test/metadata.rb
depends 'test-a'
depends 'test-b'

$ cat test/attributes/default.rb
node.default[:foo] = 'spam'