Call to Win32::Service causes rake unit to fail on Linux

[thedeafduck]

I have a cookbook that is used on both Linux and Windows platforms. In one of the recipes, that is only called if the cookbook is executed on Windows, we have:

service 'MyService' do
  action %i[enable start]
  only_if { ::Win32::Service.exists?("MyService") }
  not_if { ::File.exist?("#{install_dir}\\scripts\\instance-stopped") }
end

on Windows, rake unit works perfectly. Also, running the cookbook via a converge on either Linux or Windows also works perfectly. However, the rake unit on Linux fails with:

Failures:

myagent::install_windows When set to install agent on Windows converges successfully Failure/Error: expect { chef_run }.to_not raise_error

expected no Exception, got #<NameError: uninitialized constant Win32> with backtrace: # /tmp/chefspec20200924-2530-350e0zfile_cache_path/cookbooks/myagent/resources/install_agent.rb:83:in `block (3 levels) in class_from_file'

I have tried adding:

allow(::Win32::Service).to receive(:exists?).with(windows_service[:name]).and_return(true)

to the spec file, but this then causes the rake unit to fail on Windows and Linux.

Is there a way of telling the spec file to only use a line like the allow if we are on Linux?