如何在整个示例组中使用实例变量，即使它在示例之外？

Question

我正在使用Ruby on Rails 3.2.2和rspec-rails-2.8.1。我想在整个示例组中使用一个实例变量（在before钩子中初始化），即使它在示例之外。也就是说，我愿提出以下：

describe "..." do 
    before(:each) do 
    @user = User.create(...) 
    end 

    # Here I would like to use the instance variable but I get the error: 
    # "undefined method `firstname' for nil:NilClass (NoMethodError)" 
    @user.firstname 

    it "..." do 
    # Here it works. 
    @user.firstname 
    ... 
    end 
end 

这可能吗？如果是这样，怎么样？

---

注：我想这样做，因为我想输出的更多信息有关将要运行的测试，这种方式：

# file_name.html.erb 
... 

# General idea 
expected_value = ... 

it "... #{expected_value}" do 
    ... 
end 

# Usage that i am trying to implement 
expected_page_title = 
    I18n.translate(
    'page_title_html' 
    :user => @user.firstname # Here is the instance variable that is called and that is causing me problems 
) 

it "displays the #{expected_page_title} page title" do 
    view.content_for(:page_title).should have_content(expected_page_title) 
end 

Answer 1

你不应该需要访问RSpec设置，拆卸或测试块之外的实例变量。如果您需要修改测试主题，您可能需要创建一个明确的主题，然后再使用之前进行访问：

describe "..." do 
    subject { User.create(... } 

    before(:each) do 
    subject.firstname #whatever you plan on doing 
    end 

    it "..." do 
    # Here it works. 
    subject.firstname 
    ... 
    end 
end