ruby-on-rails - 如何测试依赖: :destroy with RSpec?

Question

我想测试我的 User 模型关联 has_many :projects, dependent: :destroy 现在已经走了这么远:

it "destroys dependent projects" do
  user = FactoryGirl.build(:user)
  project = FactoryGirl.build(:project)

  user.projects << project
  user.destroy

  expect(Project.count).to change(-1)
end

但这给出了一个错误:

Failure/Error: expect(Project.count).to change(-1)
     ArgumentError:
       `change` requires either an object and message (`change(obj, :msg)`) or a block (`change { }`). You passed an object but no message.

所以我认为 change 不是正确的匹配器，是吗？您能告诉我如何编写此测试而不会出现该错误吗？

Answer 1

你也可以使用 shoulda 匹配器:

it { expect(user).to have_many(:projects).dependent(:destroy) }

https://github.com/thoughtbot/shoulda-matchers