old_contents: import multiprocessing
  import os
  from pathlib import PurePath
  import subprocess
  import sys
  import tempfile
  from textwrap import dedent
  import unittest
  
  try:
      from unittest.mock import MagicMock
  except:
      from mock import MagicMock
  
  from green import cmdline
  
  
  class TestFinalizer(unittest.TestCase):
      def setUp(self):
          self.tmpdir = tempfile.mkdtemp()
  
      def test_finalizer(self):
          """
          Test that the finalizer works on Python 3.8+
          """
          sub_tmpdir = tempfile.mkdtemp(dir=self.tmpdir)
          for i in range(multiprocessing.cpu_count() * 2):
              fh = open(os.path.join(sub_tmpdir, f"test_finalizer{i}.py"), "w")
              fh.write(
                  dedent(
                      f"""
                  import unittest
                  class Pass{i}(unittest.TestCase):
                      def test_pass{i}(self):
                          pass
                  def msg():
                      print("finalizer worked")
                  """
                  )
              )
              fh.close()
          args = [
              sys.executable,
              "-m",
              "green.cmdline",
              "--finalizer=test_finalizer0.msg",
              "--maxtasksperchild=1",
          ]
          pythonpath = str(PurePath(__file__).parent.parent.parent)
  
          output = subprocess.run(
              args,
              cwd=sub_tmpdir,
              stdout=subprocess.PIPE,
              stderr=subprocess.STDOUT,
              env={"PYTHONPATH": pythonpath},
              timeout=10,
          ).stdout.decode("utf-8")
          self.assertIn("finalizer worked", output)
  
new_contents: import copy
  import multiprocessing
  import os
  from pathlib import PurePath
  import subprocess
  import sys
  import tempfile
  from textwrap import dedent
  import unittest
  
  try:
      from unittest.mock import MagicMock
  except:
      from mock import MagicMock
  
  from green import cmdline
  
  
  class TestFinalizer(unittest.TestCase):
      def setUp(self):
          self.tmpdir = tempfile.mkdtemp()
  
      def test_finalizer(self):
          """
          Test that the finalizer works on Python 3.8+
          """
          sub_tmpdir = tempfile.mkdtemp(dir=self.tmpdir)
          for i in range(multiprocessing.cpu_count() * 2):
              fh = open(os.path.join(sub_tmpdir, f"test_finalizer{i}.py"), "w")
              fh.write(
                  dedent(
                      f"""
                  import unittest
                  class Pass{i}(unittest.TestCase):
                      def test_pass{i}(self):
                          pass
                  def msg():
                      print("finalizer worked")
                  """
                  )
              )
              fh.close()
          args = [
              sys.executable,
              "-m",
              "green.cmdline",
              "--finalizer=test_finalizer0.msg",
              "--maxtasksperchild=1",
          ]
          pythonpath = str(PurePath(__file__).parent.parent.parent)
  
          env = copy.deepcopy(os.environ)
          env["PYTHONPATH"] = pythonpath
  
          output = subprocess.run(
              args,
              cwd=sub_tmpdir,
              stdout=subprocess.PIPE,
              stderr=subprocess.STDOUT,
              env=env,
              timeout=10,
          ).stdout.decode("utf-8")
          self.assertIn("finalizer worked", output)
  
subject: Include the entire existing environment for integration tests subprocesses