Ruby on rails 3 如何测试质量分配错误

似乎我想做与大多数人在测试rails时要求的相反的事情

如何测试ActiveModel:：MassAssignmentSecurity:：Error。我已经知道了，只是想知道如何使我的测试用例变成绿色而不是红色

当前测试：

describe Tag do
  let(:tag) { FactoryGirl.create(:tag) }
  subject { tag }

  describe "when tag name is sent directly" do
    before { tag = Tag.new(name: "New") } # <- what I want to raise the error
    it { should_not be_valid } # <- doesn't make it to this line
  end
end

但这对我也不管用，我明白了

Exception encountered: #<NoMethodError: undefined method `raise_error' for #<Class:0x00000102525c08>>

---

嘎，必须把它放在一个it{}里：

it do
  lambda { tag = Tag.new(name: "NEW") }.should raise_error
end

这为我解决了问题

it do
  lambda { tag = Tag.new(name: "NEW") }.should raise_error
end