`poetry add diagrams` fails with an AssertionError

[jacobian]

poetry add diagrams is failing with an AssertionError. pip install diagrams works as expected (as does poetry run pip install diagrams).

Python 3.8, installed via pyenv, on macOS 10.15.4, with Poetry 1.0.5.

The full error:

❯ poetry add diagrams -v
Using virtualenv: /Users/jacob/Library/Caches/pypoetry/virtualenvs/diagrams-4vZBj-48-py3.8
Using version ^0.10.0 for diagrams

Updating dependencies
Resolving dependencies... (0.0s)

[AssertionError]


Traceback (most recent call last):
  File "/Users/jacob/.local/pipx/venvs/poetry/lib/python3.8/site-packages/clikit/console_application.py", line 131, in run
    status_code = command.handle(parsed_args, io)
  File "/Users/jacob/.local/pipx/venvs/poetry/lib/python3.8/site-packages/clikit/api/command/command.py", line 120, in handle
    status_code = self._do_handle(args, io)
  File "/Users/jacob/.local/pipx/venvs/poetry/lib/python3.8/site-packages/clikit/api/command/command.py", line 171, in _do_handle
    return getattr(handler, handler_method)(args, io, self)
  File "/Users/jacob/.local/pipx/venvs/poetry/lib/python3.8/site-packages/cleo/commands/command.py", line 92, in wrap_handle
    return self.handle()
  File "/Users/jacob/.local/pipx/venvs/poetry/lib/python3.8/site-packages/poetry/console/commands/add.py", line 149, in handle
    status = installer.run()
  File "/Users/jacob/.local/pipx/venvs/poetry/lib/python3.8/site-packages/poetry/installation/installer.py", line 74, in run
    self._do_install(local_repo)
  File "/Users/jacob/.local/pipx/venvs/poetry/lib/python3.8/site-packages/poetry/installation/installer.py", line 161, in _do_install
    ops = solver.solve(use_latest=self._whitelist)
  File "/Users/jacob/.local/pipx/venvs/poetry/lib/python3.8/site-packages/poetry/puzzle/solver.py", line 36, in solve
    packages, depths = self._solve(use_latest=use_latest)
  File "/Users/jacob/.local/pipx/venvs/poetry/lib/python3.8/site-packages/poetry/puzzle/solver.py", line 180, in _solve
    result = resolve_version(
  File "/Users/jacob/.local/pipx/venvs/poetry/lib/python3.8/site-packages/poetry/mixology/__init__.py", line 7, in resolve_version
    return solver.solve()
  File "/Users/jacob/.local/pipx/venvs/poetry/lib/python3.8/site-packages/poetry/mixology/version_solver.py", line 80, in solve
    next = self._choose_package_version()
  File "/Users/jacob/.local/pipx/venvs/poetry/lib/python3.8/site-packages/poetry/mixology/version_solver.py", line 382, in _choose_package_version
    self._add_incompatibility(incompatibility)
  File "/Users/jacob/.local/pipx/venvs/poetry/lib/python3.8/site-packages/poetry/mixology/version_solver.py", line 421, in _add_incompatibility
    self._log("fact: {}".format(incompatibility))
  File "/Users/jacob/.local/pipx/venvs/poetry/lib/python3.8/site-packages/poetry/mixology/incompatibility.py", line 111, in __str__
    assert len(self._terms) == 2

[mingrammer]

I reproduced the same error with a slightly different error message. I'll check this issue. Thank you for reporting it.

[tedmiston]

I'm experiencing this as well. I thought at first it might be because my Python version is too new (3.9.5) but haven't arrived at a cause yet.

[tedmiston]

It appears to install fine via pipenv on Python 3.9.6 so I don't think Python 3.9 is the issue. Hmm.

[clintonroy]

Works fine with Poetry version 1.1.7

[n0nvme]

Same problem with poetry 1.1.10 and python 3.8.5, installed via pyenv

[Areontar]

worked for me with python 3.10 and poetry 1.1.11, I was getting the assertion error as my project was named diagrams the same name as the dependency I was trying to add. Renaming the project to something else fixed the problem for me

[kav]

Same here, which is obvious in retrospect but it might help to have a more helpful error message

[bdsoha]

@jacobian Can this be closed?