class_docstr: The CLI runner provides functionality to invoke a Click command line
  script for unittesting purposes in a isolated environment.  This only
  works in single-threaded systems without any concurrency as it changes the
  global interpreter state.
  
  :param charset: the character set for the input and output data.  This is
                  UTF-8 by default and should not be changed currently as
                  the reporting to Click only works in Python 2 properly.
  :param env: a dictionary with environment variables for overriding.
  :param echo_stdin: if this is set to `True`, then reading from stdin writes
                     to stdout.  This is useful for showing examples in
                     some circumstances.  Note that regular prompts
                     will automatically echo the input.
  :param mix_stderr: if this is set to `False`, then stdout and stderr are
                     preserved as independent streams.  This is useful for
                     Unix-philosophy apps that have predictable stdout and
                     noisy stderr, such that each may be measured
                     independently
docstr: A context manager that creates a temporary folder and changes
  the current working directory to it for isolated filesystem tests.
code: def isolated_filesystem(self):
      """A context manager that creates a temporary folder and changes
      the current working directory to it for isolated filesystem tests.
      """
      cwd = os.getcwd()
      t = tempfile.mkdtemp()
      os.chdir(t)
      try:
          yield t
      finally:
          os.chdir(cwd)
          try:
              shutil.rmtree(t)
          except (OSError, IOError):  # noqa: B014
              pass
  
imports: import contextlib
  import os
  import shlex
  import shutil
  import sys
  import tempfile
  from .None import formatting
  from .None import termui
  from .None import utils
  from ._compat import iteritems
  from ._compat import PY2
  from ._compat import string_types
label_desc: Use image node_id 6 for calling the CliRunner obj's underlying member method code with example usage: obj.isolated_filesystem() without return types