Easy testing of json API:s with Factory Girl

json_for_strategy.rb

class JsonForStrategy
  def initialize
    @strategy = FactoryGirl.strategy_by_name(:build).new
  end

  delegate :association, to: :@strategy

  def result(evaluation)
    @strategy.result(evaluation).to_json
  end
end

FactoryGirl.register_strategy(:json_for, JsonForStrategy)

Dump this in your support/ and use it like every other factory:

FactoryGirl.json_for(:my_model)
FactoryGirl.json_for(:my_model, my_attr: 'value')