Could not fetch inspec profile in 'test.rb'

I am learning InSpec, part of the ChefDK, and I have written a very basic control to test that the ssh-agent is running, saved as 'test.rb':

describe service 'ssh-agent' do 
  it { should be_running }
end 

However, when I run this control from the terminal, attempting to test the ssh-agent on my EC2 instance, I get the following error: Could not fetch inspec profile in "test.rb"

The command I run is: inspec exec test.rb -i ~/.ssh/id_rsa -t ssh://caleb.whittington@10.99.115.199

There is no issue regarding the command. I tried to add a profile by creating an inspec.yml file with the following (made-up) contents:

name: test
title: Inspec Tutorial
maintainer: Caleb Whittington
copyright: Caleb Whittington
copyright_email: <<my work email>>
license: Apache-2.0
summary: An InSpec Compliance Profile
version: 0.1.0

Does anyone know how to help? Is there an issue with my inspec.yml file, or is there another obvious issue? Thanks in advance.