new_contents: from nose.tools import assert_raises
  from helpers import TempEnvironmentHelper
  
  
  class TestFilters(TempEnvironmentHelper):
  
      def test_pyscss(self):
          """This filter used to make trouble because if required
          Environment.url and Environment.directory to be set.
          """
          self.create_files({'foo': ''})
          bundle = self.mkbundle('foo', filters='pyscss', output='out')
  
          # By default we'd get an error, because the filter can't use
          # any good defaults.
          assert_raises(EnvironmentError, bundle.build)
  
          # If we set a director/url pair, it works.
          self.env.config['PYSCSS_STATIC_ROOT'] = 'a'
          self.env.config['PYSCSS_STATIC_URL'] = 'b'
          bundle.build()
  
subject: Add a test for the PyScss filter.