This spec is failing, here https://github.com/adrienthebo/puppet/blob/f9b8af6f62da16655b24f7940233e00b8c930242/lib/puppet/ssl/certificate_authority/autosign_command.rb#L36
because it is returning nil output from the execute expectation.  We can fix this spec by providing a non-nil return; however, looking at Puppet::Util::Execution.execute, I don't think there is a guarantee that output will be non-nil.  So might want to address this autosign_command class as well, and add a spec for that case.