rspec失败“ after（：context）挂钩中发生错误。”

Question

我正在尝试执行一些涉及发送REST调用的ruby脚本，但是在注销时由于以下错误而失败。

An error occurred in an `after(:context)` hook.
Failure/Error: $root_curl_request.logout

 NoMethodError:
 undefined method `logout' for nil:NilClass
# ./lib/common/rest_spec_helper.rb:112:in `block (2 levels) in <top (required)>'

我从rest_spec_helper.rb：112下面获得了代码块

require_relative 'rest_request'
require_relative 'curl_request' 

$rest_api = RestRequest.new

 RSpec.configure do |config|
 config.before :all do
 $oracle_conn = OracleConnection.new
 ncs_server = $testbed.get_ncs_server
 root_password = ncs_server["application_root_password"] || "Public123"
 $root_curl_request = CurlRequest.new("root",root_password) unless ncs_server["application_user_name"]=="root"
 rest_add_user
 $curl_request = CurlRequest.new
 $rest_api = RestRequest.new
 $sapro_server = SaproServer.new if $testbed.get_ncs_server["sapro_server_ip"]
 time = Time.now.strftime("%d%m%Y%H%M%S")
 file="logs/auto#{time}.log"
 $log=Logger.new(file)
 $debug=true
end



config.after :all do
$debug = true
 $rest_api.logout_curl
       $curl_request.logout
 $root_curl_request.logout   // this is the 112 line 
end
end

请让我知道如何纠正此错误。