code: def test_pip_environment_variables_removed(self):
      # ensurepip deliberately ignores all pip environment variables
      # See http://bugs.python.org/issue19734 for details
      self.os_environ["PIP_THIS_SHOULD_GO_AWAY"] = "test fodder"
      with fake_pip():
          ensurepip._uninstall_helper()
      self.assertNotIn("PIP_THIS_SHOULD_GO_AWAY", self.os_environ)
  
imports: import contextlib
  import os
  import os.path
  import sys
  import tempfile
  import test.support
  import unittest
  import unittest.mock
  import ensurepip
  import ensurepip._uninstall
label_desc: Use image node_id 7 for calling the TestUninstall obj's underlying member method code with example usage: obj.test_pip_environment_variables_removed() without return types