module ActiveModel::Serializer::Lint::Tests

It is not required unless caching is enabled.
is part of the (self-expiring) cache_key, which is used by the adapter.
updated_at returns a Time object or iso8601 string and

Fails otherwise.
arguments.
Passes if the object responds to updated_at and if it takes no

def test_updated_at
  assert_respond_to resource, :updated_at
  actual_arity = resource.method(:updated_at).arity
  assert_equal 0, actual_arity
end