rspec：未找到属性（存在）错误

我在指定模型验证时遇到一些问题，该模型充当状态机（gem state_machine 0.9.4）。通过 stat_machine，我定义了对交付状态下的自行车的验证：

state :delivered do
  validates_presence_of :shipping_number
end

在我的规格中，这是正确的：

it "may not transit to :delivered without a shipping number " do
  @bike.state = 'delivered'
  @bike.shipping_number = nil
  @bike.save
  @bike.should have(1).error_on(:shipping_number)
end

但是当这样指定时：

it "may not transit to :delivered without a shipping number " do
  @bike.shipping_number = nil
  @bike.deliver
  @bike.should have(1).error_on(:shipping_number)
end

I get:

expected 1 error on :shipping_number, got 0

虽然

it "may not transit to :delivered without a shipping number " do
  @bike.shipping_number = nil
  @bike.deliver
  raise @bike.errors.inspect
end

向我展示：

Failure/Error: raise @bike.errors.inspect
#<OrderedHash {:shipping_number=>["can't be blank"]}>

有人可以解释一下吗？

检查这里的链接，它解释了这个问题：http://web.archive.org/web/20130202082209/http://agaskar.com/post/1627270986/fun-state-machine-rspec-gotcha http://web.archive.org/web/20130202082209/http://agaskar.com/post/1627270986/fun-state-machine-rspec-gotcha

底线：失败的状态转换会导致回滚到之前的状态，现在 validates_presence_of 与以下错误检查无关。

虽然可能有一种更惯用的方法来做到这一点，但我在规范中做了类似的事情：

@bike.errors.include?(:shipping_number).should == true