old_contents: import unittest
  import packaging.requirements
  import packaging.version
  
  from . import fixtures
  from .. import (
      _compat,
      version,
      )
  
  
  class IntegrationTests(fixtures.DistInfoPkg, unittest.TestCase):
  
      def test_package_spec_installed(self):
          """
          Illustrate the recommended procedure to determine if
          a specified version of a package is installed.
          """
          def is_installed(package_spec):
              req = packaging.requirements.Requirement(package_spec)
              return version(req.name) in req.specifier
  
          assert is_installed('distinfo-pkg==1.0')
          assert is_installed('distinfo-pkg>=1.0,<2.0')
          assert not is_installed('distinfo-pkg<1.0')
  
  
  class FinderTests(fixtures.Fixtures, unittest.TestCase):
  
      def test_finder_without_module(self):
          class ModuleFreeFinder(fixtures.NullFinder):
              """
              A finder without an __module__ attribute
              """
              def __getattribute__(self, name):
                  if name == '__module__':
                      raise AttributeError(name)
                  return super().__getattribute__(name)
  
          self.fixtures.enter_context(
              fixtures.install_finder(ModuleFreeFinder()))
          _compat.disable_stdlib_finder()
  
new_contents: # coding: utf-8
  
  from __future__ import unicode_literals
  
  import unittest
  import packaging.requirements
  import packaging.version
  
  from . import fixtures
  from .. import (
      _compat,
      distributions,
      version,
      )
  
  
  class IntegrationTests(fixtures.DistInfoPkg, unittest.TestCase):
  
      def test_package_spec_installed(self):
          """
          Illustrate the recommended procedure to determine if
          a specified version of a package is installed.
          """
          def is_installed(package_spec):
              req = packaging.requirements.Requirement(package_spec)
              return version(req.name) in req.specifier
  
          assert is_installed('distinfo-pkg==1.0')
          assert is_installed('distinfo-pkg>=1.0,<2.0')
          assert not is_installed('distinfo-pkg<1.0')
  
  
  class FinderTests(fixtures.Fixtures, unittest.TestCase):
  
      def test_finder_without_module(self):
          class ModuleFreeFinder(fixtures.NullFinder):
              """
              A finder without an __module__ attribute
              """
              def __getattribute__(self, name):
                  if name == '__module__':
                      raise AttributeError(name)
                  return super().__getattribute__(name)
  
          self.fixtures.enter_context(
              fixtures.install_finder(ModuleFreeFinder()))
          _compat.disable_stdlib_finder()
  
  
  class FileSystem(fixtures.OnSysPath, fixtures.SiteDir, unittest.TestCase):
      def test_unicode_dir_on_sys_path(self):
          """
          Ensure a Unicode subdirectory of a directory on sys.path
          does not crash.
          """
          fixtures.build_files({'☃': {}}, prefix=self.site_dir)
          list(distributions())
  
subject: Add test capturing failure. Ref #121.