Dropping python2 silently broke several tests

[hexagonrecursion]

I have found a couple tests that seem to be counting on python 2 to test the behavior they are designed to test even though the behaviour is not python2-specific. This is not pythin2 compatibility code but rather tests relying on python2 eg to test that markers work. Dropping python2 silently broke the tests - they no longer test what they were designed to test.

pip/tests/data/src/pep518_with_extra_and_markers-1.0/setup.py

Line 10 in bbf8466

assert simplewheel.__version__ == '1.0' if sys.version_info < (3,) else '2.0'

pip/tests/unit/test_finder.py

Lines 363 to 367 in bbf8466

	expected = ['1.0.0', '9.9.9']
	if (2, 7) < sys.version_info < (3,):
	expected.append('2.7.0')
	elif sys.version_info > (3, 3):
	expected.append('3.3.0')

pip/tests/unit/test_req.py

Lines 142 to 145 in bbf8466

	if sys.version_info[:2] == (2, 7):
	assert reqset.has_requirement('simple')
	else:
	assert not reqset.has_requirement('simple')

[ichard26]

Addressed by #10379 (thanks @jdufresne!)

[hexagonrecursion]

No! Not addressed. test_environment_marker_extras() is still broken.

Here is an English translation of what test_environment_marker_extras() is supposed to assert:
A package can use extras_require to declare dependencies that are conditional on the specific range of python versions:

setup(
  # ...
  extras_require={
      # ...
      ":python_version<'3.3'": ["monotonic"],
  }
)

Given a package, with a conditional dependency:

1. If the current version of python matches the condition, the dependency is installed
2. If the current version of python does not match the condition, the dependency is not installed

pip/tests/data/packages/LocalEnvironMarker/setup.py

Lines 20 to 27 in bbf8466

	setup(
	name='LocalEnvironMarker',
	version='0.0.1',
	packages=find_packages(),
	extras_require={
	":python_version == '2.7'": ['simple'],
	}
	)

pip/tests/unit/test_req.py

Lines 127 to 145 in bbf8466

	def test_environment_marker_extras(self, data):
	"""
	Test that the environment marker extras are used with
	non-wheel installs.
	"""
	reqset = RequirementSet()
	req = install_req_from_editable(
	data.packages.joinpath("LocalEnvironMarker")
	)
	req.user_supplied = True
	reqset.add_requirement(req)
	finder = make_test_finder(find_links=[data.find_links])
	with self._basic_resolver(finder) as resolver:
	reqset = resolver.resolve(reqset.all_requirements, True)
	# This is hacky but does test both case in py2 and py3
	if sys.version_info[:2] == (2, 7):
	assert reqset.has_requirement('simple')
	else:
	assert not reqset.has_requirement('simple')

#10379 Have removed the assertion 1 entirely

I repeat: this was not a workaround for some py2-specific legacy behaviour - requirements that are conditional based on python version are useful in modern python too. @jdufresne misunderstood the purpose of the test.

[hexagonrecursion]

pep518_with_extra_and_markers-1.0 was another test for conditional dependencies. This time in pyproject.toml:

pip/tests/data/src/pep518_with_extra_and_markers-1.0/pyproject.toml

Lines 1 to 8 in bbf8466

	[build-system]
	requires = [
	"requires_simple_extra[extra]",
	"simplewheel==1.0; python_version < '3'",
	"simplewheel==2.0; python_version >= '3'",
	"setuptools",
	"wheel",
	]

pip/tests/data/src/pep518_with_extra_and_markers-1.0/setup.py

Line 10 in bbf8466

assert simplewheel.__version__ == '1.0' if sys.version_info < (3,) else '2.0'

This test too is now broken.

[pradyunsg]

Thanks for the clarifications @hexagonrecursion! I've gone ahead and reopened this issue. :)