multiple keys for one value in yaml

That doesn't work because YAML allows you to specify keys of any type, so

[activerecord, activemodel]: 'test'

is a mapping with a single key, the sequence [activerecord, activemodel] whose value is 'test'.

Instead, you can use an anchor/alias:

activerecord: &my_value 'test'activemodel: *my_value

However, there's no way of attaching both keys to the single value in one key/value pair.

CodeHunter