(PUP-10861) Don't JSON.dump single fact values

[joshcooper]

The puppet facts show --value-only option prints just the value for a single
fact. Previously, the value was pretty printed using JSON.dump, which emitted a
quoted string. Now just print the string, so that the value can be parsed via
automation, like export OSFAMILY=puppet facts show os.family --value-only

Also add a test for multiple fact names as the --value-only option.

[joshcooper]

It looks like facter can emit [Integer, Float, TrueClass, FalseClass, NilClass, Symbol, String, Array, Hash], so I'm thinking we only want to call Json.dump for Array and Hash, and rely on to_s for the other types?

[gimmyxd]

@joshcooper I think for NilClass JSON.dump and to_s behave differently

JSON.dump(nil) #=> "null"
nil.to_s   #=> ""

But i'm not sure if Facter will return any nil value, or it will convert it before.

[joshcooper]

Facter can return nil, so I updated this (including other types in https://github.com/puppetlabs/facter/blob/0654f8f6858ca0163680b3d8dfc53d90345f0f35/lib/facter/custom_facts/util/normalization.rb#L8)

I filed https://tickets.puppetlabs.com/browse/FACT-2930 as it seems facter can emit a Date (which seems like a mistake), but the error message about VALID_TYPES is inconsistent.

[joshcooper]

grr... JRuby output is different, I'll update that.

[headius]

@joshcooper Differing output may be grounds for a JRuby bug. If whatever it was seems like it should match CRuby, could you please open a JRuby issue? https://github.com/jruby/jruby/issues

[joshcooper]

Thanks @headius! FWIW, JRuby output has an extra empty line when pretty printing, but the output is still correct, so I think it's ok? If you want it to be exactly the same, I can file a ticket?

$ bundle exec ruby -rjson -e "puts RUBY_DESCRIPTION; puts JSON.pretty_generate({})"
ruby 2.5.8p224 (2020-03-31 revision 67882) [x86_64-darwin18]
{
}

$ bundle exec ruby -rjson -e "puts RUBY_DESCRIPTION; puts JSON.pretty_generate({})"
jruby 9.2.9.0 (2.5.7) 2019-10-30 458ad3e Java HotSpot(TM) 64-Bit Server VM 25.162-b12 on 1.8.0_162-b12 +jit [darwin-x86_64]
{

}

[headius]

@joshcooper Aha, now that does ring a bell.

• JSON.pretty_generate generates different output to MRI for at least an empty hash jruby/jruby#6338
• Fix an issue with generate_pretty and empty objects in the Ruby and Java implementations ruby/json#449

So assuming this is the same issue, I think it will be resolved once the updated json gem is being used everywhere.

[headius]

JRuby 9.2.15.0 and 9.3.0.0 will ship the updated json.