Tests failing due to dependency incompatibility

[jaraco]

Tests are failing with this error:

python runtests: commands[0] | pytest --cov-config=/Users/jaraco/code/main/setuptools/tox.ini --cov-report=
Traceback (most recent call last):
  File "/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages/pluggy/manager.py", line 268, in load_setuptools_entrypoints
    plugin = ep.load()
  File "/Users/jaraco/code/main/setuptools/pkg_resources/__init__.py", line 2345, in load
    self.require(*args, **kwargs)
  File "/Users/jaraco/code/main/setuptools/pkg_resources/__init__.py", line 2368, in require
    items = working_set.resolve(reqs, env, installer, extras=self.extras)
  File "/Users/jaraco/code/main/setuptools/pkg_resources/__init__.py", line 789, in resolve
    raise VersionConflict(dist, req).with_context(dependent_req)
pkg_resources.ContextualVersionConflict: (pytest 4.1.1 (/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages), Requirement.parse('pytest<4.0.0'), {'pytest-fixture-config', 'pytest-shutil'})

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/jaraco/code/main/setuptools/.tox/python/bin/pytest", line 11, in <module>
    sys.exit(main())
  File "/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages/_pytest/config/__init__.py", line 61, in main
    config = _prepareconfig(args, plugins)
  File "/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages/_pytest/config/__init__.py", line 196, in _prepareconfig
    pluginmanager=pluginmanager, args=args
  File "/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages/pluggy/hooks.py", line 284, in __call__
    return self._hookexec(self, self.get_hookimpls(), kwargs)
  File "/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages/pluggy/manager.py", line 68, in _hookexec
    return self._inner_hookexec(hook, methods, kwargs)
  File "/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages/pluggy/manager.py", line 62, in <lambda>
    firstresult=hook.spec.opts.get("firstresult") if hook.spec else False,
  File "/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages/pluggy/callers.py", line 203, in _multicall
    gen.send(outcome)
  File "/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages/_pytest/helpconfig.py", line 93, in pytest_cmdline_parse
    config = outcome.get_result()
  File "/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages/pluggy/callers.py", line 80, in get_result
    raise ex[1].with_traceback(ex[2])
  File "/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages/pluggy/callers.py", line 187, in _multicall
    res = hook_impl.function(*args)
  File "/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages/_pytest/config/__init__.py", line 652, in pytest_cmdline_parse
    self.parse(args)
  File "/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages/_pytest/config/__init__.py", line 838, in parse
    self._preparse(args, addopts=addopts)
  File "/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages/_pytest/config/__init__.py", line 784, in _preparse
    self.pluginmanager.load_setuptools_entrypoints("pytest11")
  File "/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages/pluggy/manager.py", line 274, in load_setuptools_entrypoints
    message="Plugin %r could not be loaded: %s!" % (ep.name, e),
pluggy.manager.PluginValidationError: Plugin 'virtualenv' could not be loaded: (pytest 4.1.1 (/Users/jaraco/code/main/setuptools/.tox/python/lib/python3.7/site-packages), Requirement.parse('pytest<4.0.0'), {'pytest-fixture-config', 'pytest-shutil'})!

It seems pytest-virtualenv depends on pytest-shutil and pytest-shutil's latest release is incompatible with the latest release of pytest, but pip doesn't detect that condition so installs incompatible versions.

The underlying condition can be readily replicated thus:

$ pip-run -q pytest pytest-virtualenv -- -V                                                                                                                            
pytest-shutil 1.4.0 has requirement pytest<4.0.0, but you'll have pytest 4.1.1 which is incompatible.
pytest-fixture-config 1.4.0 has requirement pytest<4.0.0, but you'll have pytest 4.1.1 which is incompatible.
pytest-virtualenv 1.4.0 has requirement pytest<4.0.0, but you'll have pytest 4.1.1 which is incompatible.
Python 3.7.2

[jaraco]

Filed upstream issue as man-group/pytest-plugins#110

[benoit-pierre]

Re-opening, until the issue is resolved upstream and the temporary pin can be removed.

[benoit-pierre]

We can remove the pin, has a new version of the offending plugins as finally been released.