old_contents: 
  import os
  
  TESTS_RESOURCE_LOCATION = "${TESTS_RESOURCE_LOCATION}"
  
  
  def resource_path(relative_path=''):
  
      return os.path.join(TESTS_RESOURCE_LOCATION, relative_path)
  
  
  def file_contents(file_name):
  
      with open(os.path.join(TESTS_RESOURCE_LOCATION, file_name)) as f:
          content = f.read()
  
      return content
  
new_contents: 
  import os
  
  TESTS_RESOURCE_LOCATION = "${TESTS_RESOURCE_LOCATION}"
  
  
  def resource_path(relative_path=''):
  
      return TESTS_RESOURCE_LOCATION + '/' + relative_path
  
  
  def file_contents(file_name):
  
      with open(os.path.join(TESTS_RESOURCE_LOCATION, file_name)) as f:
          content = f.read()
  
      return content
  
subject: Use '/' when forming resource path for Python tests.