Override `ROOT_PATH` in specs in a less insane way

lib/gitlab_init.rb

-ROOT_PATH = File.expand_path(File.join(File.dirname(__FILE__), ".."))
+ROOT_PATH = File.expand_path('..', __dir__)
 
 require_relative 'gitlab_config'

spec/spec_helper.rb

-ROOT_PATH = File.expand_path(File.join(File.dirname(__FILE__), ".."))
-
 require 'simplecov'
 SimpleCov.start
 
@@ -13,6 +11,12 @@ VCR.configure do |c|
   c.configure_rspec_metadata!
 end
 
+RSpec.configure do |config|
+  config.before(:each) do
+    stub_const('ROOT_PATH', File.expand_path('..', __dir__))
+  end
+end
+
 # like WEBrick::HTTPServer, but listens on UNIX socket
 class HTTPUNIXServer < WEBrick::HTTPServer
   def listen(address, port)