FactoryBot.define do sequence(:calculator_amount) factory :calculator_per_item, class: Spree::Calculator::PerItem do preferred_amount { generate(:calculator_amount) } end factory :weight_calculator, class: Calculator::Weight do after(:build) { |c| c.set_preference(:per_kg, 0.5) } after(:create) { |c| c.set_preference(:per_kg, 0.5); c.save! } end end