old_contents: """build_ext tests
  """
  import unittest
  from distutils.command.build_ext import build_ext as distutils_build_ext
  from setuptools.command.build_ext import build_ext
  from setuptools.dist import Distribution
  
  class TestBuildExtTest(unittest.TestCase):
  
      def test_get_ext_filename(self):
          # setuptools needs to give back the same
          # result than distutils, even if the fullname
          # is not in ext_map
          dist = Distribution()
          cmd = build_ext(dist)
          cmd.ext_map['foo/bar'] = ''
          res = cmd.get_ext_filename('foo')
          wanted = distutils_build_ext.get_ext_filename(cmd, 'foo')
          assert res == wanted
  
new_contents: """build_ext tests
  """
  import unittest
  import distutils.command.build_ext as orig
  
  from setuptools.command.build_ext import build_ext
  from setuptools.dist import Distribution
  
  class TestBuildExtTest(unittest.TestCase):
  
      def test_get_ext_filename(self):
          # setuptools needs to give back the same
          # result than distutils, even if the fullname
          # is not in ext_map
          dist = Distribution()
          cmd = build_ext(dist)
          cmd.ext_map['foo/bar'] = ''
          res = cmd.get_ext_filename('foo')
          wanted = orig.build_ext.get_ext_filename(cmd, 'foo')
          assert res == wanted
  
subject: Use namespacing for easier reading