加个gem 'certified'

Gemfile

@@ -6,6 +6,7 @@ unless RUBY_PLATFORM =~ /w32/
   gem 'iconv'
 end
 
+gem 'certified'
 gem 'grack', path:'lib/grack'
 gem 'gitlab', path: 'lib/gitlab-cli'
 gem 'rest-client'

app/controllers/student_work_controller.rb

@@ -123,7 +123,7 @@ class StudentWorkController < ApplicationController
         #-1 默认值 0全部正确并结束 2 超时 -2 编译错误
         resultObj[:status] = -1
         resultObj[:results] = result["results"].first  #本次测试结果
-        result["error_msg"] = result["error_msg"][0..1023]
+        result["error_msg"] = result["error_msg"][0..2047]
         resultObj[:error_msg] = result["error_msg"]   #编译错误时的信息
 
         #该状态用于存入CodeTests