spec: Fix ruby execution helper

Author: mrkn

spec/support/execute_ruby.rb

@@ -4,11 +4,17 @@
 module PyCall
   module RSpecHelper
     module ExecuteRuby
+      RUBYLIB = ENV["RUBYLIB"]
+
       def ruby(script)
-        Open3.capture3(ruby_path, stdin_data: <<SCRIPT)
+        child_env = {}
+        base_dir = File.expand_path("../../..", __FILE__)
+        lib_dir = File.join(base_dir, "lib")
+        ext_dir = File.join(base_dir, "ext/pycall")
+        child_env["RUBYLIB"] = [lib_dir, ext_dir, RUBYLIB].join(File::PATH_SEPARATOR)
+        Open3.capture3(child_env, ruby_path, stdin_data: <<SCRIPT)
 require 'bundler'
 Bundler.setup
-$LOAD_PATH.unshift "#{File.expand_path('../../../lib', __FILE__)}"
 
 #{script}
 SCRIPT