Chef Inspec - How to Read Custom Properties in Files

I'm currently using Chef Inspec and want to read the content within some of my SH files. How can I get ChefInspec to read some of the properties contained within them:


ex_sh_file = location/'
describe bash(ex_sh_file) do
   it { should be_writable }
   its('custom property' ) { should eq 5 }

Is there a way for InSpec to reconfigure this? Would I have to make it read from a JSON file? What about importing node.default?