Ruby on rails 3 意外的rspec行为Ruby on Rails教程第12章

我看到的错误仅取决于线路的位置：

should change(Relationship, :count).by(-1)

例如，使用以下代码：

it "should destroy a relationship using Ajax" do
  lambda do
    xhr :delete, :destroy, :id => @relationship
    response.should be_success
  end.should change(Relationship, :count).by(-1) #<<-line is here

it "should destroy a relationship using Ajax" do
  lambda do
    xhr :delete, :destroy, :id => @relationship
    response.should be_success
    should change(Relationship, :count).by(-1) #<<-Line moved to here
  end

我得到rspec错误：

  1) RelationshipsController DELETE 'destroy' should destroy a relationship using Ajax
     Failure/Error: xhr :delete, :destroy, :id => @relationship
     ActionView::MissingTemplate:
       Missing template relationships/destroy with {:handlers=>[:erb, :rjs, :builder, :rhtml, :rxml], :formats=>[:js, :html], :locale=>[:en, :en]} in view paths "#<RSpec::Rails::ViewRendering::PathSetDelegatorResolver:0x00000100a5b5f8>"
     # ./app/controllers/relationships_controller.rb:16:in `destroy'
     # ./spec/controllers/relationships_controller_spec.rb:44:in `block (4 levels) in <top (required)>'
     # ./spec/controllers/relationships_controller_spec.rb:43:in `block (3 levels) in <top (required)>'

但对于代码：

it "should destroy a relationship using Ajax" do
  lambda do
    xhr :delete, :destroy, :id => @relationship
    response.should be_success
  end.should change(Relationship, :count).by(-1) #<<-line is here

it "should destroy a relationship using Ajax" do
  lambda do
    xhr :delete, :destroy, :id => @relationship
    response.should be_success
    should change(Relationship, :count).by(-1) #<<-Line moved to here
  end

。。。考试通过了

当我使用web浏览器时，我看到了预期的行为。取消跟踪用户将正确调整总数

---

那么，这两个rspec测试是否不相等？我被错误地保证第二次测试通过了吗？如果它们在功能上是等价的，为什么第一个会失败呢？

似乎这部分是由于

./app/controllers/relationships_controller.rb

与

粘贴到错误文件中的代码不会生成语法错误。修复错误会导致通过rspec测试