old_contents: from __future__ import unicode_literals, print_function, division, absolute_import
  from nose.tools import raises
  
  from openfisca_country_template import CountryTaxBenefitSystem
  
  tbs = CountryTaxBenefitSystem()
  
  
  def test_extension_not_already_loaded():
      assert tbs.get_variable('local_town_child_allowance') is None
  
  
  def test_load_extension():
      tbs.load_extension('openfisca_extension_template')
      assert tbs.get_variable('local_town_child_allowance') is not None
  
  
  def test_unload_extensions():
      tbs = CountryTaxBenefitSystem()
      assert tbs.get_variable('local_town_child_allowance') is None
  
  
  @raises(ValueError)
  def test_failure_to_load_extension_when_directory_doesnt_exist():
      tbs.load_extension('/this/is/not/a/real/path')
  
new_contents: from __future__ import unicode_literals, print_function, division, absolute_import
  from nose.tools import raises
  
  from openfisca_core.parameters import ParameterNode
  from openfisca_country_template import CountryTaxBenefitSystem
  
  
  tbs = CountryTaxBenefitSystem()
  
  
  def test_extension_not_already_loaded():
      assert tbs.get_variable('local_town_child_allowance') is None
  
  
  def walk_and_count(node):
      c = 0
      for item_name, item in node.children.items():
          if isinstance(item, ParameterNode):
              c += walk_and_count(item)
          else:
              c += 1
      return c
  
  
  def test_load_extension():
      assert len(tbs.variables) == 16
      assert walk_and_count(tbs.parameters) == 8
      tbs.load_extension('openfisca_extension_template')
      
      assert len(tbs.variables) == 17
      assert tbs.get_variable('local_town_child_allowance') is not None
  
      assert walk_and_count(tbs.parameters) == 9
      assert tbs.parameters.local_town.child_allowance.amount is not None
      
  
  
  def test_unload_extensions():
      tbs = CountryTaxBenefitSystem()
      assert tbs.get_variable('local_town_child_allowance') is None
  
  
  @raises(ValueError)
  def test_failure_to_load_extension_when_directory_doesnt_exist():
      tbs.load_extension('/this/is/not/a/real/path')
  
subject: Test extension's parameter access