BLD: test suite fails with latest ipython

[ZLLentz]

Expected Behavior

tests should pass

Current Behavior

with the latest ipython, there have been enough api or functional changes that the test suite no longer passes

Possible Solution

• investigate what these tests represent and if the failure represents a real issue or a testing issue
• revise the package and/or tests as appropriate for compatibility

Context

#356

[tangkong]

From my brief investigations, hutch-python sets a couple of attributes on the ipython Completer, and aside from that doesn't interact with it much.

hutch-python/hutch_python/cli.py

Lines 46 to 70 in 954d4cc

	def configure_tab_completion(ipy_config):
	"""
	Disable Jedi and tweak IPython tab completion.
	Parameters
	----------
	ipy_config : traitlets.config.Config
	IPython configuration.
	"""
	# Old API for disabling Jedi. Keep in just in case API changes back.
	ipy_config.InteractiveShellApp.Completer.use_jedi = False
	# New API for disabling Jedi (two access points documented, use both)
	ipy_config.Completer.use_jedi = False
	ipy_config.IPCompleter.use_jedi = False
	try:
	# Monkeypatch IPython completion - we need it to respect __dir__
	# when Jedi is disabled.
	# Details: https://github.com/pcdshub/pcdsdevices/issues/709
	# First, access it to see that the internals have not changed:
	IPython.core.completer.dir2
	except AttributeError:
	logger.debug('Looks like the IPython API changed!')
	else:
	# Then monkeypatch it in:
	IPython.core.completer.dir2 = dir

The test suite dove deeper into the internals (?), hitting upon an attribute that got deprecated. The line_buffer attribute is not guaranteed to exist (gh), so calling the attr_matches (gh) independently can lead to the attribute error as observed.

I'm not sure what ipython wants the public API to be here, it's not been annotated very clearly from the code itself.