def METHOD_NAME(self, shred_command_string):
    environment_changed = False
    if 'BLEACHBIT_TEST_OPTIONS_DIR' not in os.environ:
        # We need to set env var because of the new process that executes the context menu command string
        common.put_env('BLEACHBIT_TEST_OPTIONS_DIR', self.tempdir)
        environment_changed = True
    options.set('delete_confirmation', False)
    os.system(shred_command_string)
    if environment_changed:
        # We don't want to affect other tests, executed after this one.
        common.put_env('BLEACHBIT_TEST_OPTIONS_DIR', None)