ruby-on-rails - Rspec:如何测试引发错误的方法

Question

我有一个 SubscriptionHandler 类，它有一个调用方法，它创建一个挂起的订阅，尝试向用户收费，然后如果收费失败则出错。无论计费是否失败，都会创建待定订阅

class SubscriptionHandler

  def initialize(customer, stripe_token)
    @customer = customer
    @stripe_token = stripe_token
  end

  def call
    create_pending_subscription
    attempt_charge!
    upgrade_subscription
  end

  private

  attr_reader :stripe_token, :customer

  def create_pending_subscription
   @subscription = Subscription.create(pending: true, customer_id: customer.id)
  end

  def attempt_charge!
    StripeCharger.new(stripe_token).charge!  #raises FailedPaymentError
  end

  def upgrade_subscription
   @subscription.update(pending: true)
  end

 end

这是我的规范:

describe SubscriptionHandler do

  describe "#call" do
    it "creates a pending subscription" do
      customer = create(:customer)
      token = "token-xxx"
      charger = StripeCharger.new(token)
      allow(StripeCharger).to receive(:new).and_return(charger)
      allow(charger).to receive(:charge!).and_raise(FailedPaymentError)
      handler = SubscriptionHandler.new(customer, token)

      expect { handler.call }.to change { Subscription.count }.by(1) # Fails with FailedPaymentError
    end
  end
end

但这不会改变订阅计数，它会因 FailedPaymentError 而失败。有没有一种方法可以检查订阅计数是否增加而规范不会因 FailedPaymentError 而崩溃。

Answer 1

你应该能够为此使用 Rspec 复合期望

https://relishapp.com/rspec/rspec-expectations/docs/compound-expectations

所以我会把你的期望重写成这样:

expect { handler.call }.
 to raise_error(FailedPaymentError).
 and change { Subscription.count }.by(1)