ruby-on-rails - Rspec should_receive 在一个没有行为的实例上

Question

我有一个类方法，它只是遍历一些记录并在每条记录上执行一个实例方法。我正在尝试为类方法编写一个简单的测试，以确保它将实例方法发送到每条记录。

it "fires any pending alarms" do
  pending       = create :alarm, :pending
  other_pending = create :alarm, :pending

  # sanity check
  Alarm.pending.sort.should eq [pending, other_pending].sort

  pending.should_receive(:fire)
  other_pending.should_receive(:fire)

  Alarm.fire_pending
end

报警.rb

class Alarm < ActiveRecord::Base
  scope :pending, where(pending: true)

  def self.fire_pending
    self.pending.each do |alarm|
      alarm.fire
    end
  end
end

但是我在 should_receive 期望上收到错误:

 Failure/Error: pending.should_receive(:fire)
   (#<Alarm:0x007fcc96334310>).fire(any args)
       expected: 1 time
       received: 0 times

我之前成功使用过这个期望。恐怕我遗漏了一些明显的东西。

编辑

我现在已经解决了这个问题:

it "fires any pending alarms" do
  pending       = create :alarm, :pending
  other_pending = create :alarm, :pending

  pending_alarms = Alarm.pending
  pending_alarms.sort.should eq [pending, other_pending].sort

  Alarm.stub(:pending) { pending_alarms }
  pending_alarms.first.should_receive(:fire)
  pending_alarms.last.should_receive(:fire)

  Alarm.fire_pending
end

但我不太喜欢那样，想知道为什么我的第一次尝试不起作用。

Answer 1

Alarm.pending 返回的对象与示例中创建的实例不同。您可以通过更改看到这一点:

pending_alarms.sort.should eq [pending, other_pending].sort

到:

# the eq matcher uses == (object equivalence)
# the equal matcher uses equals? (object identity)
pending_alarms.sort.tap do |sorted|
  sorted[0].should eq pending       # passes
  sorted[1].should eq other_pending # passes
  sorted[0].should equal pending       # fails
  sorted[1].should equal other_pending # fails
end

这是使用(邪恶的)any_instance 的好例子:

it "fires any pending alarms" do
  pending = create :alarm, :pending
  Pending.any_instance.should_receive(:fire)
  Alarm.fire_pending
end