意外的 rspec 行为 Ruby on Rails Turorial 第 12 章

Question

我看到一个仅取决于行位置的错误：

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

例如，使用代码：

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

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)>'

但是使用代码：

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

...测试通过。

当我使用网络浏览器时，我看到了预期的行为。取消关注用户可以正确调整总数。

那么，这两个 rspec 测试不等效吗？我是否错误地确信第二次测试会通过？如果它们在功能上是等效的，为什么第一个会失败？

Answer 1

似乎这在一定程度上是由于

./app/controllers/relationships_controller.rb

与

./spec/controllers/relationships_controller_spec.rb

粘贴到错误文件中的代码（适当地）混淆而没有产生语法错误。修复我的错误导致通过 rspec 测试。