module I18n::Base

I18n.interpolation_keys('example') #=> []
I18n.interpolation_keys('does-not-exist') #=> []
I18n.interpolation_keys('one', scope: 'example', locale: :other) #=> ['baz']
I18n.interpolation_keys('example.three') #=> ['foo', 'bar', 'baz']
I18n.interpolation_keys('example.two') #=> ['foo', 'bar']
I18n.interpolation_keys('example.one') #=> ['foo']
I18n.interpolation_keys('example.zero') #=> []
Then we can expect the following results:

I18n.t 'example.one', locale: :other == 'One interpolation %{baz}'
I18n.t 'example.three' == ['One %{foo}', 'Two %{bar}', 'Three %{baz}']
I18n.t 'example.two' == 'Two interpolations %{foo} %{bar}'
I18n.t 'example.one' == 'One interpolation %{foo}'
I18n.t 'example.zero' == 'Zero interpolations'
Suppose we have the following:

*Examples*

Returns an array of interpolation keys for the given translation key

def interpolation_keys(key, **options)
  raise I18n::ArgumentError if !key.is_a?(String) || key.empty?
  return [] unless exists?(key, **options.slice(:locale, :scope))
  translation = translate(key, **options.slice(:locale, :scope))
  interpolation_keys_from_translation(translation)
    .flatten.compact
end