如何使用 RSpec 正确测试 CanCan 功能

Question

我第一次测试 CanCan 的能力，被难住了。我错过了一些东西......即使我在 can :invite_to 块内返回 false/true，我仍然没有获得通过的规格。我是否缺少使用 CanCan 匹配器？或存根？或者在 CanCan 中定义能力？

我缺少什么吗？

ability.rb

class Ability
  include CanCan::Ability

  def initialize(user)
    user ||= User.new

    can :invite_to, Network do |network|
      network.allows_invitations? && (user.admin? || user.can_send_invitations_for?(network))
    end
  end
end

ability_spec.rb

require 'cancan'
require 'cancan/matchers'
require_relative '../../app/models/ability.rb'

class Network; end;

describe Ability do
  let(:ability) { Ability.new(@user) }

  describe "#invite_to, Network" do
    context "when network level invitations are enabled" do
      let(:network) { stub(allows_invitations?: true) }

      it "allows an admin" do
        @user = stub(admin?: true)
        ability.should be_able_to(:invite_to, network)
      end

      it "allows a member if the member's invitation privileges are enabled" do
        @user = stub(admin?: false, can_send_invitations_for?: true)
        ability.should be_able_to(:invite_to, network)
      end

      it "denies a member if the member's invitation privileges are disabled" do
        @user = stub(admin?: false, can_send_invitations_for?: false)
        ability.should_not be_able_to(:invite_to, network)
      end
    end
  end
end

失败

  1) Ability#invite_to, Network when network level invitations are enabled allows an admin
     Failure/Error: ability.should be_able_to(:invite_to, network)
       expected to be able to :invite_to #<RSpec::Mocks::Mock:0x3fe3ed90444c @name=nil>
     # ./spec/models/ability_spec.rb:16:in `block (4 levels) in <top (required)>'

  2) Ability#invite_to, Network when network level invitations are enabled allows a member if the member's invitation privileges are enabled
     Failure/Error: ability.should be_able_to(:invite_to, network)
       expected to be able to :invite_to #<RSpec::Mocks::Mock:0x3fe3edc27408 @name=nil>
     # ./spec/models/ability_spec.rb:21:in `block (4 levels) in <top (required)>'

Answer 1

  let(:network) do 
    n = Network.new
    n.stub!(:allows_invitations? => true)
    n
  end

如果您按照编写的方式运行代码，则永远不会到达 Can 块内的代码。对存根的调用返回 RSpec::Mocks::Mock 类的对象；它必须属于 Network 类，CanCan 才能应用该规则。