Inherit belongs_to through

[Scaffale]

Using:

Rails 6.0.0
ruby 2.6.4

More a "how to" then an issue:

Class 1 (the top level class)

class AbstractResult < ApplicationRecord
  actable
  belongs_to :person
end

Class 2 (act_as abstract_result)

class TestResult < ApplicationRecord
  acts_as :abstract_result
  has_one :test_spatial_result, dependent: :destroy
end

Class 3 (belonging to class 2)

class TestSpatialResult < ApplicationRecord
  belongs_to :test_result
  has_one person, through: :test_result
end

Now, If I try

test_result.person

it works properly, but if I try

test_spatial_result.person

it won't work.

How can be done the inheritance of the belongs to through the polymorphic association?