`CliRunner.invoke` takes `mix_stderr` which does nothing

[adamtheturtle]

mix_stderr is a parameter of CliRunner.invoke.
This is not documented in the docstring as a :param.
Simply reading the code (which I did after trying this and seeing no output) shows that this parameter is not used.

mix_stderr works on CliRunner.__init__.

The mix_stderr parameter should be removed, or changed to work and get documented.

[davidism]

Fairly sure this is fixed in master

[adamtheturtle]

@davidism I believe that it is not.

See on master the parameter list includes mix_stderr:

click/click/testing.py

Lines 280 to 281 in 6944450

	def invoke(self, cli, args=None, input=None, env=None,
	catch_exceptions=True, color=False, mix_stderr=False, **extra):

The parameter documentation does not include mix_stderr:

click/click/testing.py

Lines 296 to 311 in 6944450

	.. versionadded:: 4.0
	The ``color`` parameter was added.
	:param cli: the command to invoke
	:param args: the arguments to invoke. It may be given as an iterable
	or a string. When given as string it will be interpreted
	as a Unix shell command. More details at
	:func:`shlex.split`.
	:param input: the input data for `sys.stdin`.
	:param env: the environment overrides.
	:param catch_exceptions: Whether to catch any other exceptions than
	``SystemExit``.
	:param extra: the keyword arguments to pass to :meth:`main`.
	:param color: whether the output should contain color codes. The
	application can still override this explicitly.
	"""

And the function code does not include mix_stderr:

click/click/testing.py

Lines 312 to 357 in 6944450

	exc_info = None
	with self.isolation(input=input, env=env, color=color) as outstreams:
	exception = None
	exit_code = 0
	if isinstance(args, string_types):
	args = shlex.split(args)
	try:
	prog_name = extra.pop("prog_name")
	except KeyError:
	prog_name = self.get_default_prog_name(cli)
	try:
	cli.main(args=args or (), prog_name=prog_name, **extra)
	except SystemExit as e:
	exc_info = sys.exc_info()
	exit_code = e.code
	if exit_code is None:
	exit_code = 0
	if exit_code != 0:
	exception = e
	if not isinstance(exit_code, int):
	sys.stdout.write(str(exit_code))
	sys.stdout.write('\n')
	exit_code = 1
	except Exception as e:
	if not catch_exceptions:
	raise
	exception = e
	exit_code = 1
	exc_info = sys.exc_info()
	finally:
	sys.stdout.flush()
	stdout = outstreams[0].getvalue()
	stderr = outstreams[1] and outstreams[1].getvalue()
	return Result(runner=self,
	stdout_bytes=stdout,
	stderr_bytes=stderr,
	exit_code=exit_code,
	exception=exception,
	exc_info=exc_info)

[jcrotts]

I think this is at least partially fixed here:
#1194

[adamtheturtle]

I think this is at least partially fixed here:
#1194

@jcrotts I don't think that #1194 relates to this issue - this issue concerns CliRunner.invoke and that PR concerns CliRunner.__init__.

[jcrotts]

Some behavior is changed in CliRunner.invoke, the docstring isn't changed though.
https://github.com/pallets/click/pull/1194/files#diff-637edab3f8e0763a9874d17879193dc9R350

[adamtheturtle]

I still don't understand how that in any way addresses this issue, which is that the mix_stderr parameter to CliRunner.invoke does nothing.

[davidism]

Hi Adam, you seem to have a specific idea in mind that we're having trouble understanding. If this is important to you and you have the time, it would probably be easier to create a PR fixing the issue rather than going back and forth more.

[adamtheturtle]

Good idea @davidism . I have created #1442 . I'm happy to back port / change this if you are happy with the general idea.

[adamtheturtle]

@jcrotts @davidism - I hope that the linked PR makes it clear what this issue is.

[miker985]

I also just ran into this issue and was confused why stderr and stdout were mixed.

Since it's easy to set this on the CliRunner object I endorse the #1442