Puppet Case insensitivity

I was helping my friend roll out some new services today and a section of his Puppet code caught my eye. This is what I saw:

...
  case $::kernel {
    'linux': {
...

This caught my eye because I had been explicitly capitalizing the 'L' in the $::kernel fact for years. I thought to myself "Is the fact capitalized?"

zeratul:~# facter -p kernel
Linux

What's going on here? Is the case operator insensitive?

case $::kernel {
  'sunos': { notify { $::kernel: }}
}
notice: SunOS
notice: /Stage[main]//Notify[SunOS]/message: defined 'message' as 'SunOS'

Wow. Is the '==' operator in Puppet case-insensitive as well?

if $::kernel == 'sunos' {
  notify { 'lasers': }
}
notice: lasers
notice: /Stage[main]//Notify[lasers]/message: defined 'message' as 'lasers'

Is this a problem with facter or puppet?

if "YES" == "yes" {
  notify { "false is true": }
}
notice: false is true
notice: /Stage[main]//Notify[false is true]/message: defined 'message' as 'false is true'

Seriously? Yep. Turns out the '==' operator is case-insensitive. The '=~' is case-sensitive, but you have to use regular expression syntax in order to use it:

if "YES" =~ /^yes$/ {
  notify { "false is true": }
}
notice: Finished catalog run in 1.30 seconds

Note that we should use '^$' to enclose the string so we don't accidentally get a substring match.

Tested on Puppet 2.7.x and 3.2.x