old_contents: #
  # Unit tests for the viewer.utils module.
  #
  # Copyright: (c) 2014 by Petr Zemek <s3rvac@gmail.com> and contributors
  # License: BSD, see LICENSE for more details
  #
  
  import os
  import unittest
  from unittest import mock
  
  from viewer.utils import chdir
  
  
  @mock.patch('os.chdir')
  class ChdirTests(unittest.TestCase):
      def setUp(self):
          self.orig_cwd = os.getcwd()
          self.dst_dir = 'test'
  
      def test_os_chdir_is_called_with_dst_dir_in_entry(self, mock_chdir):
          with chdir(self.dst_dir):
              mock_chdir.assert_called_once_with(self.dst_dir)
  
      def test_os_chdir_is_called_with_orig_cwd_in_exit(self, mock_chdir):
          with chdir(self.dst_dir):
              mock_chdir.reset_mock()
          mock_chdir.assert_called_once_with(self.orig_cwd)
  
      def test_os_chdir_is_called_with_orig_cwd_in_exit_even_if_exception_occurs(
              self, mock_chdir):
          try:
              with chdir(self.dst_dir):
                  mock_chdir.reset_mock()
                  raise RuntimeError
          except RuntimeError:
              mock_chdir.assert_called_once_with(self.orig_cwd)
  
  
new_contents: #
  # Unit tests for the viewer.utils module.
  #
  # Copyright: (c) 2014 by Petr Zemek <s3rvac@gmail.com> and contributors
  # License: BSD, see LICENSE for more details
  #
  
  import os
  import unittest
  from unittest import mock
  
  from viewer.utils import chdir
  
  
  @mock.patch('os.chdir')
  class ChdirTests(unittest.TestCase):
      def setUp(self):
          self.orig_cwd = os.getcwd()
          self.dst_dir = 'test'
  
      def test_os_chdir_is_called_with_dst_dir_in_entry(self, mock_chdir):
          with chdir(self.dst_dir):
              mock_chdir.assert_called_once_with(self.dst_dir)
  
      def test_os_chdir_is_called_with_orig_cwd_in_exit(self, mock_chdir):
          with chdir(self.dst_dir):
              mock_chdir.reset_mock()
          mock_chdir.assert_called_once_with(self.orig_cwd)
  
      def test_os_chdir_is_called_with_orig_cwd_in_exit_even_if_exception_occurs(
              self, mock_chdir):
          try:
              with chdir(self.dst_dir):
                  mock_chdir.reset_mock()
                  raise RuntimeError
          except RuntimeError:
              mock_chdir.assert_called_once_with(self.orig_cwd)
  
subject: Remove a redundant empty line.