poetry export --with-credentials fails under tox with tox-poetry-installer

[ejd]

I used poetry config http-basic.private-index __token__ TOKEN to store credentials for a private package index. I have a tox testenv that runs poetry export --with-credentials to generate a requirements file. When the testenv runs poetry export --with-credentials under tox, it prints the following message:

No suitable keyring backends were found
Using a plaintext file to store and retrieve credentials

The resulting output contains the username part of the index credentials but is missing the password part:

--extra-index-url https://__token__:@example.com/pypi/simple

When I run poetry export --with-credentials on the command line, poetry doesn't print the warning and its output contains both the username and password for the index, like this:

--extra-index-url https://__token__:TOKEN@example.com/pypi/simple

Should I expect to be able to run poetry export --with-credentials under tox with tox-poetry-installer installed? Here is some information I thought would be helpful in diagnosing my problem. I'm happy to provide other details if needed.

~/.poetry/bin/poetry is the copy of poetry that the testenv runs -- I checked with which poetry in the testenv. I'm not sure if it's relevant, but running .tox/.tox/bin/poetry export --with-credentials on the command line also produces the correct output with the username and password present.

Poetry version: 1.1.15
tox version: 3.25.1
Poetry installation method:

curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/get-poetry.py | python3.9 -

tox.ini:

[tox]
minversion = 3.3.0
isolated_build = True
requires = tox-poetry-installer[poetry] == 0.8.4

[testenv]
sitepackages = False
require_poetry = True
require_locked_deps = True

[testenv:export]
skip_install = True
allowlist_externals = poetry
commands = poetry export --with-credentials

Relevant portion of pyproject.toml:

[[tool.poetry.source]]
name = "private-index"
url = "https://example.com/pypi/simple"
secondary = true

poetry.toml:

[repositories]
[repositories.private-index]
url = "https://example.com/pypi/simple"

[ejd]

This isn't an issue with tox-poetry-installer. I found jaraco/keyring#283 which explains that I need to have the following in the testenv that does poetry export:

passenv =
    DBUS_SESSION_BUS_ADDRESS

Otherwise, keyring can't connect to the dbus session.

Sorry for the confusion!