Here is the one liner i use, from terminal, to test the content of yml file(s):
$ ruby -r yaml -r pp -e 'pp YAML.load_file("/Users/za/project/application.yml")'
{"logging"=>
{"path"=>"/var/logs/",
"file"=>"TacoCloud.log",
"level"=>
{"root"=>"WARN", "org"=>{"springframework"=>{"security"=>"DEBUG"}}}}}