[test] avoid "class variable access from toplevel"

Author: kares

src/test/ruby/test_helper.rb

@@ -63,7 +63,7 @@ def self.plugin_output_init(options)
 
 puts "#{__FILE__} using #{TestCase}" if $VERBOSE || defined?(REPORT_PATH)
 
-TestCase.class_eval do
+class TestCase
 
   def setup; require 'openssl' end