Merge pull request #44 from enpaul/enp/resolver

Fix compatibility check failures in the core resolver

.github/scripts/setup-env.sh

@@ -0,0 +1,72 @@
+#!/usr/bin/env bash
+#
+# Environment setup script for the local project. Intended to be used with automation
+# to create a repeatable local environment for tests to be run in. The python env
+# this script creates can be accessed at the location defined by the CI_VENV variable
+# below.
+
+set -e;
+
+# ##### Prereqs #####
+#
+# Set global vars for usage in the script, create the cache directory so we can rely
+# on that existing, then dump some diagnostic info for later reference.
+#
+CI_VENV=$HOME/ci;
+CI_CACHE=$HOME/.cache;
+CI_CACHE_GET_POETRY="$CI_CACHE/get-poetry.py";
+CI_POETRY=$HOME/.poetry/bin/poetry;
+CI_VENV_PIP="$CI_VENV/bin/pip";
+CI_VENV_PIP_VERSION=19.3.1;
+CI_VENV_TOX="$CI_VENV/bin/tox";
+
+mkdir --parents "$CI_CACHE";
+
+command -v python;
+python --version;
+
+# ##### Install Poetry #####
+#
+# Download the poetry install script to the cache directory and then install poetry.
+# After dump the poetry version for later reference.
+#
+curl https://raw.githubusercontent.com/python-poetry/poetry/master/get-poetry.py \
+  --output "$CI_CACHE_GET_POETRY" \
+  --silent \
+  --show-error \
+  --location;
+python "$CI_CACHE_GET_POETRY" --yes 1>/dev/null;
+
+python "$CI_POETRY" --version --no-ansi;
+
+# ##### Setup Runtime Venv #####
+#
+# Create a virtual environment for poetry to use, upgrade pip in that venv to a pinned
+# version, then install the current project to the venv.
+#
+# Note 1: Poetry, Tox, and this project plugin all use pip under the hood for package
+#         installation. This means that even though we are creating up to eight venvs
+#         during a given CI run they all share the same download cache.
+# Note 2: The "VIRTUAL_ENV=$CI_VENV" prefix on the poetry commands below sets the venv
+#         that poetry will use for operations. There is no CLI flag for poetry that
+#         directs it to use a given environment, but if it finds itself in an existing
+#         environment it will use it and skip environment creation.
+#
+python -m venv "$CI_VENV";
+
+$CI_VENV_PIP install "pip==$CI_VENV_PIP_VERSION" \
+  --upgrade \
+  --quiet;
+
+VIRTUAL_ENV=$CI_VENV "$CI_POETRY" install \
+  --extras poetry \
+  --quiet \
+  --no-ansi \
+  &>/dev/null;
+
+# ##### Print Debug Info #####
+#
+# Print the pip and tox versions (which will include registered plugins)
+#
+$CI_VENV_PIP --version;
+echo "tox $($CI_VENV_TOX --version)";

.github/workflows/ci.yaml

@@ -17,25 +17,54 @@ jobs:
             toxenv: py37
           - version: 3.8
             toxenv: py38
+          - version: 3.9
+            toxenv: py39
     steps:
-      - uses: actions/checkout@v2
-      - name: Set up Python ${{ matrix.python.version }}
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Setup:python${{ matrix.python.version }}
         uses: actions/setup-python@v1
         with:
           python-version: ${{ matrix.python.version }}
-      - name: Install project
-        run: pip install .
-      - name: Run tests via ${{ matrix.python.toxenv }}
-        run: tox -e ${{ matrix.python.toxenv }}
+      - name: Setup:cache
+        uses: actions/cache@v2
+        with:
+          path: |
+            ~/.cache/pip
+            ~/.cache/pypoetry/cache
+            ~/.poetry
+          # Including the hashed poetry.lock in the cache slug ensures that the cache
+          # will be invalidated, and thus all packages will be redownloaded, if the
+          # lockfile is updated
+          key: ${{ runner.os }}-${{ matrix.python.toxenv }}-${{ hashFiles('**/poetry.lock') }}
+      - name: Setup:env
+        run: .github/scripts/setup-env.sh
+      - name: Run:${{ matrix.python.toxenv }}
+        run: $HOME/ci/bin/tox -e ${{ matrix.python.toxenv }} --require-poetry
   Check:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - name: Set up Python 3.8
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Setup:python3.8
         uses: actions/setup-python@v1
         with:
           python-version: 3.8
-      - name: Install project
-        run: pip install .
-      - name: Run meta checks
-        run: tox -e static -e static-tests -e security
+      - name: Setup:cache
+        uses: actions/cache@v2
+        with:
+          path: |
+            ~/.cache/pip
+            ~/.cache/pypoetry/cache
+            ~/.poetry
+          # Hardcoded 'py38' slug here lets this cache piggyback on the 'py38' cache
+          # that is generated for the tests above
+          key: ${{ runner.os }}-py38-${{ hashFiles('**/poetry.lock') }}
+      - name: Setup:env
+        run: .github/scripts/setup-env.sh
+      - name: Run:static
+        run: $HOME/ci/bin/tox -e static --require-poetry
+      - name: Run:static-tests
+        run: $HOME/ci/bin/tox -e static-tests --require-poetry
+      - name: Run:security
+        run: $HOME/ci/bin/tox -e security --require-poetry

.pre-commit-config.yaml

@@ -1,28 +1,69 @@
 ---
+# All of the pre-commit hooks here actually use the `pytyhon` pre-commit language
+# setting. However, for the python language setting, pre-commit will create and manage
+# a cached virtual environment for each hook ID and do a bare `pip install <repo>` into
+# the venv to setup the hook. This can result in conflicting dependency versions between
+# the version installed to the pre-commit venv and the version installed to the Poetry
+# venv specified in the lockfile.
+#
+# The solution is to specify `language: system` for all hooks and then install the
+# required dependencies to the Poetry venv. The `system` language skips the isolated
+# venv creation and looks for the entrypoint specified by the hook in the global
+# environment which, if running in the Poetry venv, will find the entrypoint provided
+# by the Poetry-managed dependency.
+#
 repos:
-  - repo: https://github.com/psf/black
-    rev: 20.8b1
-    hooks:
-      - id: black
-        language_version: python3
-
-  - repo: https://github.com/asottile/blacken-docs
-    rev: v0.5.0
-    hooks:
-      - id: blacken-docs
-        additional_dependencies: [black==20.8b1]
-        language_version: python3
-
-  - repo: https://github.com/asottile/reorder_python_imports
-    rev: v2.3.5
-    hooks:
-      - id: reorder-python-imports
-        language_version: python3
-
-  - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v2.0.0
+  - repo: local
     hooks:
       - id: end-of-file-fixer
+        name: end-of-file-fixer
+        entry: end-of-file-fixer
+        language: system
+        types:
+          - text
+
       - id: fix-encoding-pragma
-        args: [--remove]
-      - id: trailing-whitespace
+        name: fix-encoding-pragma
+        entry: fix-encoding-pragma
+        language: system
+        args:
+          - "--remove"
+        types:
+          - python
+
+      - id: trailing-whitespace-fixer
+        name: trailing-whitespace-fixer
+        entry: trailing-whitespace-fixer
+        language: system
+        types:
+          - text
+
+      - id: check-merge-conflict
+        name: check-merge-conflict
+        entry: check-merge-conflict
+        language: system
+        types:
+          - text
+
+      - id: reorder-python-imports
+        name: reorder-python-imports
+        entry: reorder-python-imports
+        language: system
+        args:
+          - "--unclassifiable-application-module=tox_poetry_installer"
+        types:
+          - python
+
+      - id: black
+        name: black
+        entry: black
+        language: system
+        types:
+          - python
+
+      - id: blacken-docs
+        name: blacken-docs
+        entry: blacken-docs
+        language: system
+        types:
+          - text

CHANGELOG.md

@@ -0,0 +1,242 @@
+# changelog
+
+See also: [Github Release Page](https://github.com/enpaul/tox-poetry-installer/releases).
+
+
+## Version 0.6.3
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.6.3),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.6.3/)
+
+* Update required `tox` version from `^3.0` to `^3.8` to avoid compatibility issues
+* Update logging messages to improve UX
+* Fix transient dependency packages being installed in a pseudo-random order due to Python
+  sets being unordered ([#41](https://github.com/enpaul/tox-poetry-installer/issues/41))
+* Fix outdated docstrings
+
+
+## Version 0.6.2
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.6.2),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.6.2/)
+
+* Update locked version of `py` to `1.10.0` to address
+  [CVE-2020-29651](https://nvd.nist.gov/vuln/detail/CVE-2020-29651)
+* Fix dependency identification failing when the package under test is a transient dependency
+  of a locked dependency specified for installation
+* Fix `AttributeError` being raised while creating the Tox self-provisioned environment when
+  using either the [`minversion`](https://tox.readthedocs.io/en/latest/config.html#conf-minversion)
+  or [`requires`](https://tox.readthedocs.io/en/latest/config.html#conf-requires) Tox config options
+
+
+## Version 0.6.1
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.6.1),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.6.1/)
+
+* Update logging around transient dependency processing to improve debugging of dependency
+  installation problems
+* Fix regression around handling of Poetry's unsafe packages when the unsafe package is a
+  transient dependency ([#33](https://github.com/enpaul/tox-poetry-installer/issues/33))
+* Fix handling of Poetry's unsafe packages when the unsafe package is a primary (environment
+  or package) dependency
+
+
+## Version 0.6.0
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.6.0),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.6.0/)
+
+* Add `poetry` extra to support installing Poetry as a direct dependency of the plugin
+* Add `--require-poetry` runtime option to force Tox failure if Poetry is not installed
+* Update logging messages to improve UX around non-verbose messaging
+* Update error logging to avoid dumping stack traces
+* Update integration with Tox's `action` object to better manage internal state at runtime
+* Update documentation to more clearly cover more use cases
+* Remove `poetry` as a required dependency to support external Poetry installations
+
+First beta release :tada:
+
+
+## Version 0.5.2
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.5.2),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.5.2/)
+
+* Fix always attempting to install dependencies with incompatible python version constraints
+* Fix always attempting to install dependencies with incompatible python platforms
+
+
+## Version 0.5.1
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.5.1),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.5.1/)
+
+* Add CI/Tox tests for Python-3.9
+* Update dependency processing to reduce duplication during installation
+* Update minimum python requirement to `3.6.1`
+* Fix `UnboundLocal` exception when not installing project dependencies
+
+
+## Version 0.5.0
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.5.0),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.5.0/)
+
+* Add option `locked_deps` to better support both locked and unlocked dependencies in a
+  single environment
+* Add blocking functionality when using `require_locked_deps = true` to prevent other
+  hooks from running after this one
+* Update documentation to include new configuration options and errors
+* Update documentation to improve future maintainability
+* Update module structure to move from single-file module to multi-file directory module
+* Fix `RecursionError` when installing locked dependencies that specify recursive dependencies
+* Fix always reinstalling all locked dependencies on every run regardless of update status
+
+
+## Version 0.4.0
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.4.0),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.4.0/)
+
+* Add `install_dev_deps` configuration option for automatically installing all Poetry
+  dev-dependencies into a Tox testenv
+
+
+## Version 0.3.1
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.3.1),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.3.1/)
+
+* Fix error when installing an environment with no extras specified in the configuration
+* Fix problem where only the dependencies of the sequentially last extra would be installed
+* Fix regression causing no project dependencies to be installed
+
+
+## Version 0.3.0
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.3.0),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.3.0/)
+
+* Add support for the Tox [`extras`](https://tox.readthedocs.io/en/latest/config.html#conf-extras)
+  configuration parameter
+* Update runtime-skip-conditional checks to improve clarity and ease of future maintenance
+* Update lockfile parsing to avoid parsing it multiple times for a single testenv
+* Fix missing `poetry-core` dependency when using Poetry<1.1.0
+
+
+## Version 0.2.4
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.2.4),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.2.4/)
+
+* Fix support for Poetry-1.1 ([#2](https://github.com/enpaul/tox-poetry-installer/issues/2))
+* Include tests in sdist ([#8](https://github.com/enpaul/tox-poetry-installer/issues/8))
+
+
+## Version 0.2.3
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.2.3),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.2.3/)
+
+* Fix usage of the plugin in non-Poetry based projects ([#1](https://github.com/enpaul/tox-poetry-installer/issues/1))
+* Fix treating dependency names as case sensitive when they shouldn't be ([#7](https://github.com/enpaul/tox-poetry-installer/issues/7))
+
+
+## Version 0.2.2
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.2.2),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.2.2/)
+
+* Fix breaking when running Tox in projects that do not use Poetry for their environment/dependency
+  management ([#1](https://github.com/enpaul/tox-poetry-installer/issues/1))
+
+
+## Version 0.2.1
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.2.1),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.2.1/)
+
+* Fix duplicate installation of transient environment dependencies
+* Fix logging error indicating all environments always have zero dependencies
+* Fix installing main dependencies when `skip_install` is false but `skipdist` is true
+
+
+## Version 0.2.0
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.2.0),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.2.0/)
+
+* Add support for per-environment configuration setting `require_locked_deps`
+* Add support for per-dependency lock requirement setting using `@poetry` suffix
+* Add support for coexisting locked and unlocked dependencies in a single test environment
+* Update documentation to include more usage examples
+* Update documentation to improve clarity around problems and drawbacks
+* Fix logging messages being inconsistently formatted
+* Fix raising the same exception for "locked dependency not found" and "locked dependency
+  specifies alternate version" errors
+* Fix plugin errors not reporting to Tox that they happened
+* Fix plugin errors not causing Tox to mark the env as failed
+
+
+## Version 0.1.3
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.1.3),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.1.3/)
+
+* Fix core functionality of installing dependencies from lockfile for the package-under-development
+  ("dev-package") built by Tox
+* Fix log messages not being displayed with Tox output
+* Add additional logging output for diagnostics
+* Update Poetry requirement to exclude upcoming Poetry-1.1.0 release which will break compatibility
+
+This is the first release where the core functionality actually works as expected :tada:
+
+
+## Version 0.1.2
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.1.2),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.1.2/)
+
+* Test trivial functionality on Python-3.6 and Python-3.7
+* Fix disagreement between `pyproject.toml` and module metadata on what the current version is
+* Fix constant named for PEP-440 that should have been named for PEP-508
+
+
+## Version 0.1.1
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.1.1),
+[PyPI](https://pypi.org/project/tox-poetry-installer/0.1.1/)
+
+* Add/update project documentation
+* Add static analysis and formatting enforcement automation to toxfile
+* Add security analysis to toxfile
+* Fix raising `KeyError` for unlocked dependencies
+* Fix mishandling of Poetry's "unsafe dependencies"
+* Lint, blacken, and generally improve code quality
+
+
+## Version 0.1.0
+
+View this release on:
+[Github](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.1.0),
+
+* Add support for installing Tox environment dependencies using Poetry from the Poetry lockfile

Makefile

@@ -19,7 +19,7 @@ clean-py:
 	rm --recursive --force ./dist
 	rm --recursive --force ./build
 	rm --recursive --force ./*.egg-info
-	rm --recursive --force __pycache__/
+	rm --recursive --force ./**/__pycache__/
 
 clean: clean-tox clean-py; ## Clean temp build/cache files and directories
 
@@ -32,5 +32,9 @@ source: ## Build Python source distribution package
 test: ## Run the project testsuite(s)
 	poetry run tox --recreate
 
-publish: wheel source ## Build and upload to pypi (requires $PYPI_API_KEY be set)
-	poetry publish --username __token__ --password $(PYPI_API_KEY)
+dev: ## Create the local dev environment
+	poetry install -E poetry
+	poetry run pre-commit install
+
+publish: test wheel source ## Build and upload to pypi (requires $PYPI_API_KEY be set)
+	@poetry publish --username __token__ --password $(PYPI_API_KEY)

README.md

@@ -3,24 +3,28 @@
 A plugin for [Tox](https://tox.readthedocs.io/en/latest/) that allows test environment
 dependencies to be installed using [Poetry](https://python-poetry.org/) from its lockfile.
 
-⚠️ **This project is alpha software and should not be used in production environments** ⚠️
+⚠️ **This project is beta software and is under active development** ⚠️
 
-[![ci-status](https://github.com/enpaul/tox-poetry-installer/workflows/CI/badge.svg?event=push)](https://github.com/enpaul/tox-poetry-installer/actions)
-[![license](https://img.shields.io/pypi/l/tox-poetry-installer)](https://opensource.org/licenses/MIT)
-[![pypi-version](https://img.shields.io/pypi/v/tox-poetry-installer)](https://pypi.org/project/tox-poetry-installer/)
-[![python-versions](https://img.shields.io/pypi/pyversions/tox-poetry-installer)](https://www.python.org)
+[![CI Status](https://github.com/enpaul/tox-poetry-installer/workflows/CI/badge.svg?event=push)](https://github.com/enpaul/tox-poetry-installer/actions)
+[![PyPI Version](https://img.shields.io/pypi/v/tox-poetry-installer?color=%2331c854)](https://pypi.org/project/tox-poetry-installer/)
+[![PyPI Downloads](https://img.shields.io/pypi/dm/tox-poetry-installer?color=%2331c854)](https://libraries.io/pypi/tox-poetry-installer)
+[![License](https://img.shields.io/pypi/l/tox-poetry-installer?color=%2331c854)](https://opensource.org/licenses/MIT)
+[![Python Supported Versions](https://img.shields.io/pypi/pyversions/tox-poetry-installer)](https://www.python.org)
 [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
 
+See the [Changelog](https://github.com/enpaul/tox-poetry-installer/blob/devel/CHANGELOG.md) for release history.
+
 **Documentation**
 
-* [Installation](#installation)
+* [Introduction](#introduction)
+  * [Install](#install)
   * [Quick Start](#quick-start)
-* [Reference and Usage](#reference-and-usage)
-  * [Config Option Reference](#config-option-reference)
-  * [Error Reference](#error-reference)
-  * [Example Config](#example-config)
-* [Known Drawbacks and Problems](#known-drawbacks-and-problems)
   * [Why would I use this?](#why-would-i-use-this) (What problems does this solve?)
+* [Reference](#reference)
+  * [Configuration Options](#configuration-options)
+  * [Command-line Arguments](#command-line-arguments)
+  * [Errors](#errors)
+  * [Advanced Usage](#advanced-usage)
 * [Developing](#developing)
 * [Contributing](#contributing)
 * [Roadmap](#roadmap)
@@ -30,42 +34,95 @@ dependencies to be installed using [Poetry](https://python-poetry.org/) from its
 Related resources:
 * [Poetry Python Project Manager](https://python-poetry.org/)
 * [Tox Automation Project](https://tox.readthedocs.io/en/latest/)
-* [Poetry Dev-Dependencies Tox Plugin](https://github.com/sinoroc/tox-poetry-dev-dependencies)
-* [Poetry Tox Plugin](https://github.com/tkukushkin/tox-poetry)
 * [Other Tox plugins](https://tox.readthedocs.io/en/latest/plugins.html)
 
+Similar projects:
+* [Poetry Dev-Dependencies Tox Plugin](https://github.com/sinoroc/tox-poetry-dev-dependencies)
+* [Poetry Tox Plugin](https://github.com/tkukushkin/tox-poetry)
 
-## Installation
 
-Add the plugin as a development dependency of a Poetry project:
+## Introduction
 
-```
-~ $: poetry add tox-poetry-installer --dev
+This is a plugin to unify two great projects in the Python ecosystem: the
+[Tox](https://tox.readthedocs.io/en/latest/) automation project and the
+[Poetry](https://python-poetry.org) project/dependency manager. Specifically it allows
+the repeatable dependency resolution and installation tools that Poetry uses to benefit
+the isolated environments that Tox uses to run automated tests. The motivation to write
+this plugin came from a need for a single source of truth for the versions of all
+packages that should be installed to an environment.
+
+When in use this plugin will allow a Tox environment to install its required
+dependencies using the versions specified in the Poetry lockfile. This eliminates
+needing to specify package versions in multiple places as well as ensures that the Tox
+environment has the exact same versions of a given package as the Poetry environment.
+This reduces (or hopefully eliminates) hard to debug problems caused by subtle
+differences in the dependency graph of the active development environment (the one managed
+by Poetry) and the automated test environment(s) created by Tox.
+
+To learn more about the problems this plugin aims to solve jump ahead to
+[What problems does this solve?](#why-would-i-use-this).
+Otherwise keep reading to get started.
+
+### Install
+
+The recommended way to install the plugin is to add it to a project's `pyproject.toml`
+and lockfile using Poetry:
+
+```bash
+poetry add tox-poetry-installer[poetry] --dev
 ```
 
-Confirm that the plugin is installed, and Tox recognizes it, by checking the Tox version:
+**WARNING:** The below installation methods are vulnerable to the
+[transient dependency issues this plugin aims to avoid](#why-would-i-use-this). It is
+always recommended to install dependencies using Poetry whenever possible.
+
+The plugin can also be installed with pip directly, though it is recommended to always
+install to a virtual environment and pin to a specific version:
+
+```bash
+source my-venv/bi/activate
+pip install tox-poetry-installer[poetry] == 0.6.0
+```
+
+The plugin can also be installed using the Tox
+[`requires`]((https://tox.readthedocs.io/en/latest/config.html#conf-requires))
+configuration option. Note however that dependencies installed via the `requires` option
+are not handled by the plugin and will be installed the same way as a `pip install ...`
+above. For this reason it is also recommended to always pin to a specific version when
+using this installation method:
+
+```ini
+# tox.ini
+[tox]
+requires
+    tox-poetry-installer[poetry] == 0.6.0
+```
+
+Check that the plugin is registered by checking the Tox version:
 
 ```
 ~ $: poetry run tox --version
 3.20.0 imported from .venv/lib64/python3.8/site-packages/tox/__init__.py
 registered plugins:
-    tox-poetry-installer-0.2.2 at .venv/lib64/python3.8/site-packages/tox_poetry_installer.py
+    tox-poetry-installer-0.6.0 at .venv/lib64/python3.8/site-packages/tox_poetry_installer.py
 ```
 
-If using Pip, ensure that the plugin is installed to the same environment as Tox:
+**NOTE:** Installing the `tox-poetry-installer[poetry]` extra will add the `poetry`
+package as a managed environment dependency which can cause problems when the Poetry
+installation is externally managed (such as in a CI or container environment). See
+[Advanced Usage](#installing-alongside-an-existing-poetry-installation) for more
+information on this use case.
 
-```
-# Calling the virtualenv's 'pip' binary directly will cause pip to install to that virtualenv
-~ $: /path/to/my/automation/virtualenv/bin/pip install tox
-~ $: /path/to/my/automation/virtualenv/bin/pip install tox-poetry-installer
-```
+### Quick Start
 
+Before making any changes to `tox.ini` the project is already benefiting from having
+the plugin installed: all dependencies of the root project package are installed using
+the Poetry backend to all Tox environments that install the root package without any
+configuration changes.
 
-## Quick Start
-
-To add dependencies from the lockfile to a Tox environment, add the option `locked_deps`
-to the environment configuration and list names of dependencies (with no version
-specifier) under it:
+To add dependencies from the lockfile to a Tox environment, add the option
+[`locked_deps`](#locked_deps) to the environment configuration and list names of
+dependencies (with no version specifier) under it:
 
 ```ini
 [testenv]
@@ -77,9 +134,9 @@ locked_deps =
 commands = ...
 ```
 
-The standard `deps` option can be used in parallel with the `locked_deps` option to
-install unlocked dependencies (dependencies not in the lockfile) alongside locked
-dependencies:
+The standard [`deps`](https://tox.readthedocs.io/en/latest/config.html#conf-deps) option
+can be used in parallel with the `locked_deps` option to install unlocked dependencies
+(dependencies not in the lockfile) alongside locked dependencies:
 
 ```ini
 [testenv]
@@ -95,170 +152,37 @@ commands = ...
 ```
 
 Alternatively, to quickly install all Poetry dev-dependencies to a Tox environment, add the
-`install_dev_deps =  true` option to the environment configuration.
-
-**Note:** Regardless of the settings outlined above, all dependencies of the project package (the
-one Tox is testing) will always be installed from the lockfile.
-
-
-## Reference and Usage
-
-### Config Option Reference
-
-All options listed below are Tox environment options and can be applied to one or more
-environment sections of the `tox.ini` file. They cannot be applied to the global Tox
-configuration section.
-
-**NOTE:** Environment settings applied to the main `testenv` environment will be
-inherited by child environments (i.e. `testenv:foo`) unless they are explicitly
-overridden by the child environment's configuration.
-
-| Option                | Type            | Default | Usage                                          |
-|:----------------------|:----------------|:--------|:-----------------------------------------------|
-| `locked_deps`         | Multi-line list | `[]`    | Names of packages in the Poetry lockfile to install to the Tox environment. All dependencies specified here (and their dependencies) will be installed to the Tox environment using the version the Poetry lockfile specifies for them. |
-| `require_locked_deps` | Bool            | `false` | Indicates whether the environment should allow unlocked dependencies (dependencies not in the Poetry lockfile) to be installed alongside locked dependencies. If `true` then installation of unlocked dependencies will be blocked and an error will be raised if the `deps` option specifies any values. |
-| `install_dev_deps`    | Bool            | `false` | Indicates whether all Poetry development dependencies should be installed to the environment. Provides a quick and easy way to install all dev-dependencies without needing to specify them individually. |
-
-### Error Reference
-
-* `LockedDepVersionConflictError` - Indicates that a locked dependency included a PEP-508 version
-  specifier (i.e. `pytest >=6.0, <6.1`). Locked dependencies always take their version from the
-  Poetry lockfile so specifying a specific version for a locked dependency is not supported.
-* `LockedDepNotFoundError` - Indicates that a locked dependency could not be found in the Poetry
-  lockfile. This can be solved by [adding the dependency using Poetry](https://python-poetry.org/docs/cli/#add).
-* `ExtraNotFoundError` - Indicates that the Tox `extras` option specified a project extra that
-  Poetry does not know about. This may be due to a misconfigured `pyproject.toml` or out of date
-  lockfile.
-* `LockedDepsRequiredError` - Indicates that an environment with `require_locked_deps = true` also
-  specified unlocked dependencies using Tox's `deps` option. This can be solved by either setting
-  `require_locked_deps = false` (the default) or removing the `deps` option from the environment
-  configuration.
-
-### Example Config
+[`install_dev_deps`](#install_dev_deps) option to the environment configuration:
 
 ```ini
-[tox]
-envlist = py, foo, bar, baz
-isolated_build = true
-
-# The base testenv will always use locked dependencies and only ever installs the project package
-# (and its dependencies) and the two pytest dependencies listed below
 [testenv]
 description = Some very cool tests
-require_locked_deps = true
-locked_deps =
-    pytest
-    pytest-cov
-commands = ...
-
-# This environment also requires locked dependencies, but the "skip_install" setting means that
-# the project dependencies will not be installed to the environment from the lockfile
-[testenv:foo]
-description = FOObarbaz
-skip_install = true
-require_locked_deps = true
-locked_deps =
-    requests
-    toml
-    ruamel.yaml
-commands = ...
-
-# This environment allows unlocked dependencies to be installed ad-hoc. Below, the "mypy" and
-# "pylint" dependencies (and their dependencies) will be installed from the Poetry lockfile but the
-# "black" dependency will be installed using the default Tox backend. Note, this environment does
-# not specify "require_locked_deps = true" to allow the unlocked "black" dependency without raising
-# an error.
-[testenv:bar]
-description = fooBARbaz
-locked_deps =
-    mypy
-    pylint
-deps =
-    black
-commands = ...
-
-# This environment requires locked dependencies but does not specify any. Instead it specifies the
-# "install_dev_deps = true" option which will cause all of the Poetry dev-dependencies to be
-# installed from the lockfile.
-[testenv:baz]
-description = foobarBAZ
 install_dev_deps = true
-require_locked_deps = true
-commands = ...
 ```
 
+See the [Reference](#reference) section for more details on available
+configuration options and the [Advanced Usage](#advanced-usage) section for some
+unusual use cases.
 
-## Known Drawbacks and Problems
-
-* The following `tox.ini` configuration options have no effect on the dependencies installed from
-  the Poetry lockfile (note that they will still affect unlocked dependencies):
-  * [`install_command`](https://tox.readthedocs.io/en/latest/config.html#conf-install_command)
-  * [`pip_pre`](https://tox.readthedocs.io/en/latest/config.html#conf-pip_pre)
-  * [`downloadcache`](https://tox.readthedocs.io/en/latest/config.html#conf-downloadcache) (deprecated)
-  * [`download`](https://tox.readthedocs.io/en/latest/config.html#conf-download)
-  * [`indexserver`](https://tox.readthedocs.io/en/latest/config.html#conf-indexserver)
-  * [`usedevelop`](https://tox.readthedocs.io/en/latest/config.html#conf-indexserver)
-
-* Tox will not automatically detect changes to the locked dependencies and so
-  environments will not be automatically rebuilt when locked dependencies are changed.
-  When changing the locked dependencies (or their versions) the environments will need to
-  be manually rebuilt using either the `-r`/`--recreate` CLI option or the
-  `recreate = true` option in `tox.ini`.
-
-* There are a handful of packages that cannot be installed from the lockfile, whether as specific
-  dependencies or as transient dependencies (dependencies of dependencies). This is due to
-  [an ongoing discussion in the Poetry project](https://github.com/python-poetry/poetry/issues/1584);
-  the list of dependencies that cannot be installed from the lockfile can be found
-  [here](https://github.com/python-poetry/poetry/blob/cc8f59a31567f806be868aba880ae0642d49b74e/poetry/puzzle/provider.py#L55).
-  This plugin will skip these dependencies entirely, but log a warning when they are encountered.
-
-
-## Why would I use this?
-
-**Introduction**
-
-The lockfile is a file generated by a package manager for a project that records what
-dependencies are installed, the versions of those dependencies, and any additional metadata that
-the package manager needs to recreate the local project environment. This allows developers
-to have confidence that a bug they are encountering that may be caused by one of their
-dependencies will be reproducible on another device. In addition, installing a project
-environment from a lockfile gives confidence that automated systems running tests or performing
-builds are using the same environment as a developer.
-
-[Poetry](https://python-poetry.org/) is a project dependency manager for Python projects, and
-so it creates and manages a lockfile so that its users can benefit from all the features
-described above. [Tox](https://tox.readthedocs.io/en/latest/#what-is-tox) is an automation tool
-that allows Python developers to run tests suites, perform builds, and automate tasks within
-self-contained [Python virtual environments](https://docs.python.org/3/tutorial/venv.html).
-To make these environments useful Tox supports installing dependencies in each environment.
-However, since these environments are created on the fly and Tox does not maintain a lockfile,
-there can be subtle differences between the dependencies a developer is using and the
-dependencies Tox uses.
-
-This is where this plugin comes into play.
-
-By default Tox uses [Pip](https://docs.python.org/3/tutorial/venv.html) to install the
-PEP-508 compliant dependencies to a test environment. This plugin extends the default
-Tox dependency installation behavior to support installing dependencies using a Poetry-based
-installation method that makes use of the dependency metadata from Poetry's lockfile.
+### Why would I use this?
 
 **The Problem**
 
+By default Tox uses Pip to install the [PEP-508](https://www.python.org/dev/peps/pep-0508/)
+compliant dependencies to a test environment. This plugin extends the default Tox
+dependency installation behavior to support installing dependencies using a Poetry-based
+installation method that makes use of the dependency metadata from Poetry's lockfile.
+
 Environment dependencies for a Tox environment are usually specified in PEP-508 format, like
 the below example:
 
 ```ini
-# from tox.ini
-...
-
 [testenv]
 description = Some very cool tests
 deps =
     foo == 1.2.3
     bar >=1.3,<2.0
     baz
-
-...
 ```
 
 Let's assume these dependencies are also useful during development, so they can be added to the
@@ -312,9 +236,6 @@ less stable than the one presented above because it does not specify any version
 dependencies:
 
 ```ini
-# from tox.ini
-...
-
 [testenv]
 description = Some very cool tests
 require_locked_deps = true
@@ -322,21 +243,248 @@ locked_deps =
     foo
     bar
     baz
-
-...
 ```
 
-However with the `tox-poetry-installer` plugin installed the `require_locked_deps = true`
-setting means that Tox will install these dependencies from the Poetry lockfile so that the
-version installed to the Tox environment exactly matches the version Poetry is managing. When
-`poetry update` updates the lockfile with new versions of these dependencies, Tox will
-automatically install these new versions without needing any changes to the configuration.
+However with the `tox-poetry-installer` plugin installed Tox will install these
+dependencies from the Poetry lockfile so that the version installed to the Tox
+environment exactly matches the version Poetry is managing. When `poetry update` updates
+the lockfile with new versions of these dependencies, Tox will automatically install
+these new versions without needing any changes to the configuration.
+
+
+## Reference
+
+### Configuration Options
+
+All options listed below are Tox environment options and can be applied to one or more
+environment sections of the `tox.ini` file. They cannot be applied to the global Tox
+configuration section.
+
+**NOTE:** Environment settings applied to the main `testenv` environment will be
+inherited by child environments (i.e. `testenv:foo`) unless they are explicitly
+overridden by the child environment's configuration.
+
+#### `locked_deps`
+
+* **Type:** multi-line list
+* **Default:** `[]`
+
+Names of packages in the Poetry lockfile to install to the Tox environment. All
+dependencies specified here will be installed to the Tox environment using the details
+given by the Poetry lockfile.
+
+#### `require_locked_deps`
+
+
+* **Type:** boolean
+* **Default:** `false`
+
+Whether the environment should allow unlocked dependencies (dependencies not in the
+Poetry lockfile) to be installed alongside locked dependencies. If `true` then an error
+will be raised if the environment specifies unlocked dependencies to install and the
+plugin will block any other plugins from using the
+[`tox_testenv_install_deps`](https://tox.readthedocs.io/en/latest/plugins.html#tox.hookspecs.tox_testenv_install_deps)
+hook.
+
+#### `install_dev_deps`
+
+* **Type:** boolean
+* **Default:** `false`
+
+Whether all Poetry dev-dependencies should be installed to the environment. If `true`
+then all dependencies specified in the
+[`dev-dependencies`](https://python-poetry.org/docs/pyproject/#dependencies-and-dev-dependencies)
+section of `pyproject.toml` will be installed automatically.
+
+### Command-line Arguments
+
+All arguments listed below can be passed to the `tox` command to modify runtime behavior
+of the plugin.
+
+#### `--require-poetry`
+
+Indicates that Poetry is expected to be available to Tox and, if it is not, then the Tox
+run should fail. If provided and the `poetry` package is not installed to the same
+environment as the `tox` package then Tox will fail.
+
+**NOTE:** See [Advanced Usage](#installing-alongside-an-existing-poetry-installation)
+for more information.
+
+### Errors
+
+If the plugin encounters an error while processing a Tox environment then it will mark
+the environment as failed and set the environment status to one of the values below:
+
+**NOTE:** In addition to the reasons noted below, the plugin can encounter errors if the
+Poetry lockfile is not up-to-date with `pyproject.toml`. To resynchronize the
+lockfile with the `pyproject.toml` run one of
+[`poetry update`](https://python-poetry.org/docs/cli/#update) or
+[`poetry lock`](https://python-poetry.org/docs/cli/#lock)
+
+#### Poetry Not Installed Error
+
+* **Status value:** `PoetryNotInstalledError`
+* **Cause:** Indicates that the `poetry` module could not be imported from the same
+  environment as the running `tox` module and the runtime flags specified
+  [`--require-poetry`](#--require-poetry).
+* **Resolution options:**
+  * Install Poetry: ensure that `poetry` is installed to the same environment as `tox`.
+  * Skip running the plugin: remove the `--require-poetry` flag from the runtime options.
+
+**NOTE:** See [Advanced Usage](#installing-alongside-an-existing-poetry-installation)
+for more information.
+
+#### Locked Dependency Version Conflict Error
+
+* **Status value:** `LockedDepVersionConflictError`
+* **Cause:** Indicates that a dependency specified in the [`locked_deps`](#locked_deps)
+  configuration option in `tox.ini` includes a
+  [PEP-508 version specifier](https://www.python.org/dev/peps/pep-0508/#grammar)
+  (i.e. `pytest >=6.0, <6.1`).
+* **Resolution options:**
+  * Use the dependency version from the lockfile: remove any/all version specifiers
+    from the item in the `locked_deps` list in `tox.ini`.
+  * Do not install the dependency: remove the item from the `locked_deps` list in
+    `tox.ini`.
+
+#### Locked Dependency Not Found Error
+
+* **Status value:** `LockedDepNotFoundError`
+* **Cause:** Indicates that a dependency specified in the [`locked_deps`](#locked_deps)
+  configuration option in `tox.ini` could not be found in the Poetry lockfile.
+* **Resolution options:**
+  * Add the dependency to the lockfile: run
+    [`poetry add <dependency>`](https://python-poetry.org/docs/cli/#add).
+  * Do not install the dependency: remove the item from the `locked_deps` list in
+    `tox.ini`.
+
+#### Extra Not Found Error
+
+* **Status value:** `ExtraNotFoundError`
+* **Cause:** Indicates that the [`extras`](https://tox.readthedocs.io/en/latest/config.html#conf-extras)
+  configuration option specified a setuptools extra that is not configured by Poetry in
+  `pyproject.toml`
+* **Resolution options:**
+  * Configure the extra: add a section for the named extra to the
+    [`extras`](https://python-poetry.org/docs/pyproject/#extras) section of
+    `pyproject.toml` and optionally assign dependencies to the named extra using the
+    [`--optional`](https://python-poetry.org/docs/cli/#options_3) dependency setting.
+  * Remove the extra: remove the item from the `extras` list in `tox.ini`.
+
+#### Locked Dependencies Required Error
+
+* **Status value:** `LockedDepsRequiredError`
+* **Cause:** Indicates that an environment with the [`require_locked_deps`](#require_locked_deps)
+  configuration option also specified unlocked dependencies using
+  [`deps`](https://tox.readthedocs.io/en/latest/config.html#conf-deps) option in
+  `tox.ini`.
+* **Resolution options:**
+  * Remove all unlocked dependencies: remove the `deps` configuration option in
+    `tox.ini`.
+  * Allow unlocked dependencies: remove the `require_locked_deps` configuration option
+    in `tox.ini` or explicitly set `require_locked_deps = false`.
+
+### Advanced Usage
+
+#### Unsupported Tox configuration options
+
+The `tox.ini` configuration options listed below have no effect on the dependencies
+installed by this plugin the Poetry lockfile. Note that these settings will still be
+applied by the default Tox installation backend when installing unlocked dependencies
+using the built-in `deps` option.
+
+  * [`install_command`](https://tox.readthedocs.io/en/latest/config.html#conf-install_command)
+  * [`pip_pre`](https://tox.readthedocs.io/en/latest/config.html#conf-pip_pre)
+  * [`download`](https://tox.readthedocs.io/en/latest/config.html#conf-download)
+  * [`indexserver`](https://tox.readthedocs.io/en/latest/config.html#conf-indexserver)
+  * [`usedevelop`](https://tox.readthedocs.io/en/latest/config.html#conf-indexserver)
+
+All of these options are obsoleted by using the Poetry backend. If a given package
+installs successfully using Poetry (using either `poetry add <package>` or
+`poetry install`) then the required configuration options are already properly set in
+the Poetry configuration and the plugin will automatically use the same settings when
+installing the package.
+
+#### Reinstalling locked dependencies to a Tox environment
+
+Updating the `poetry.lock` file will not automatically cause Tox to install the updated
+lockfile specifications to the Tox environments that specify them.
+
+The Tox environment(s) with updated locked dependencies must be deleted and recreated
+using the [`--recreate`](https://tox.readthedocs.io/en/latest/config.html#cmdoption-tox-r)
+runtime flag. Alternatively Tox can be configured to always recreate an environment by
+setting the [`recreate`](https://tox.readthedocs.io/en/latest/config.html#conf-recreate)
+option in `tox.ini`.
+
+#### Installing Poetry's unsafe dependencies
+
+There are several packages that cannot be installed from the lockfile because they are
+excluded by Poetry itself. As a result these packages cannot be installed by this plugin
+either as environment dependencies (passed directly to [`locked_deps`](#locked_deps)) or
+as transient dependencies (a dependency of a locked dependency).
+
+As of [Poetry-1.1.4](https://github.com/python-poetry/poetry/releases/tag/1.1.4) there
+are four packages classified as "unsafe" by Poetry and excluded from the lockfile:
+
+* `setuptools`
+* `distribute`
+* `pip`
+* `wheel`
+
+When one of these packages is encountered by the plugin a warning will be logged and
+_**the package will not be installed to the environment**_. If the unsafe package
+is required for the environment then it will need to be specified as an unlocked
+dependency using the [`deps`](https://tox.readthedocs.io/en/latest/config.html#conf-deps)
+configuration option in `tox.ini`, ideally with an exact pinned version.
+
+* The set of packages excluded from the Poetry lockfile can be found in
+  [`poetry.puzzle.provider.Provider.UNSAFE_DEPENDENCIES`](https://github.com/python-poetry/poetry/blob/master/poetry/puzzle/provider.py)
+* There is an ongoing discussion of Poetry's handling of these packages at
+  [python-poetry/poetry#1584](https://github.com/python-poetry/poetry/issues/1584)
+
+#### Installing alongside an existing Poetry installation
+
+The plugin specifies the `poetry` package as an optional dependency to support an
+externally managed Poetry installation such as in a container or CI environment. This
+gives greater flexibility when using Poetry arguments like `--no-root`, `--no-dev`, or
+`--remove-untracked` which can cause Poetry to uninstall itself if Poetry is specified
+as a dependency of one of the packages it is managing (like this plugin).
+
+To have the plugin use the externally-managed Poetry package simply do not install the
+`poetry` extra when installing this plugin:
+
+```bash
+# Installing Poetry as a dependency with the plugin
+poetry add tox-poetry-installer[poetry]
+
+# Relying on an externally managed Poetry installation
+poetry add tox-poetry-installer
+```
+
+Note that Poetry is an optional dependency to support this use case _only_: Poetry must
+be installed to the same environment as Tox for the plugin to function. To check that
+the local environment has all of the required modules in scope run the below command:
+
+```bash
+python -c '\
+  import tox;\
+  import tox_poetry_installer;\
+  from poetry.poetry import Poetry;\
+'
+```
+
+**NOTE:** To force Tox to fail if Poetry is not installed, run the `tox` command with
+the [`--require-poetry`](#--require-poetry) option.
 
 
 ## Developing
 
-This project requires a developer to have Poetry version 1.0+ installed on their workstation, see
-the [installation instructions here](https://python-poetry.org/docs/#installation).
+Local development requirements:
+* Python version 3.6+ ([install](https://www.python.org/downloads/))
+* Poetry version 1.0+ ([install](https://python-poetry.org/docs/#installation))
+* GNU Make (optional, required to use the makefile)
+
+Local environment setup instructions:
 
 ```bash
 # Clone the repository...
@@ -345,22 +493,30 @@ git clone https://github.com/enpaul/tox-poetry-installer.git
 # ...over SSH
 git clone git@github.com:enpaul/tox-poetry-installer.git
 
-# Create a the local project virtual environment and install dependencies
-cd tox-poetry-installer
-poetry install
+cd tox-poetry-installer/
 
-# Install pre-commit hooks
-poetry run pre-commit install
+# Create and configure the local development environment
+make dev
 
-# Run tests and static analysis
-poetry run tox
+# Run tests and CI locally
+make test
+
+# Check additional make targets
+make help
 ```
 
+**NOTE:** Because the pre-commit hooks require dependencies in the Poetry environment it
+is recommend to [launch an environment shell](https://python-poetry.org/docs/cli/#shell)
+when developing the project. Alternatively, many `git` commands will need to be run from
+outside of the environment shell by prefacing the command with
+[`poetry run`](https://python-poetry.org/docs/cli/#run).
+
 
 ## Contributing
 
 All project contributors and participants are expected to adhere to the
-[Contributor Covenant Code of Conduct, Version 2](CODE_OF_CONDUCT.md).
+[Contributor Covenant Code of Conduct, v2](CODE_OF_CONDUCT.md)
+([external link](https://www.contributor-covenant.org/version/2/0/code_of_conduct/)).
 
 The `devel` branch has the latest (potentially unstable) changes. The
 [tagged versions](https://github.com/enpaul/tox-poetry-installer/releases) correspond to the
@@ -369,7 +525,7 @@ releases on PyPI.
 * To report a bug, request a feature, or ask for assistance, please
   [open an issue on the Github repository](https://github.com/enpaul/tox-poetry-installer/issues/new).
 * To report a security concern or code of conduct violation, please contact the project author
-  directly at **ethan dot paul at enp dot one**.
+  directly at **‌me [at‌] enp dot‎ ‌one**.
 * To submit an update, please
   [fork the repository](https://docs.github.com/en/enterprise/2.20/user/github/getting-started-with-github/fork-a-repo)
   and
@@ -378,10 +534,10 @@ releases on PyPI.
 
 ## Roadmap
 
-This project is under active development and is classified as alpha software, not yet ready
-for usage in production environments.
+This project is under active development and is classified as beta software, ready for
+production environments on a provisional basis only.
 
-* Beta classification will be assigned when the initial feature set is finalized
+* Beta classification was assigned with [v0.6.0](https://github.com/enpaul/tox-poetry-installer/releases/tag/0.6.0)
 * Stable classification will be assigned when the test suite covers an acceptable number of
   use cases
 
@@ -393,24 +549,26 @@ for usage in production environments.
       Tox configuration option ([#4](https://github.com/enpaul/tox-poetry-installer/issues/4))
 - [X] Add per-environment Tox configuration option to fall back to default installation
       backend.
-- [ ] Add warnings when an unsupported Tox configuration option is detected while using the
-      Poetry backend. ([#5](https://github.com/enpaul/tox-poetry-installer/issues/5))
+- [ ] ~Add warnings when an unsupported Tox configuration option is detected while using the
+      Poetry backend.~ ([#5](https://github.com/enpaul/tox-poetry-installer/issues/5))
 - [X] Add trivial tests to ensure the project metadata is consistent between the pyproject.toml
       and the module constants.
 - [X] Update to use [poetry-core](https://github.com/python-poetry/poetry-core) and
       improve robustness of the Tox and Poetry module imports
       to avoid potentially breaking API changes in upstream packages. ([#2](https://github.com/enpaul/tox-poetry-installer/issues/2))
-- [ ] Find and implement a way to mitigate the [UNSAFE_DEPENDENCIES issue](https://github.com/python-poetry/poetry/issues/1584) in Poetry.
+- [ ] ~Find and implement a way to mitigate the [UNSAFE_DEPENDENCIES issue](https://github.com/python-poetry/poetry/issues/1584) in Poetry.~
       ([#6](https://github.com/enpaul/tox-poetry-installer/issues/6))
-- [ ] Fix logging to make proper use of Tox's logging reporter infrastructure ([#3](https://github.com/enpaul/tox-poetry-installer/issues/3))
+- [X] Fix logging to make proper use of Tox's logging reporter infrastructure ([#3](https://github.com/enpaul/tox-poetry-installer/issues/3))
 - [X] Add configuration option for installing all dev-dependencies to a testenv ([#14](https://github.com/enpaul/tox-poetry-installer/issues/14))
 
 ### Path to Stable
 
 Everything in Beta plus...
 
-- [ ] Add tests for each feature version of Tox between 2.3 and 3.20
-- [ ] Add tests for Python-3.6, 3.7, and 3.8
+- [ ] Fully replace dependency on `poetry` with dependency on `poetry-core` ([#2](https://github.com/enpaul/tox-poetry-installer/issues/2))
+- [ ] Add comprehensive unit tests
+- [ ] Add tests for each feature version of Tox between 3.0 and 3.20
+- [X] Add tests for Python-3.6, 3.7, 3.8, and 3.9
 - [X] Add Github Actions based CI
 - [ ] Add CI for CPython, PyPy, and Conda
 - [ ] Add CI for Linux and Windows

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "tox-poetry-installer"
-version = "0.5.0"
+version = "0.6.4"
 license = "MIT"
 authors = ["Ethan Paul <24588726+enpaul@users.noreply.github.com>"]
 description = "Tox plugin to install Tox environment dependencies using the Poetry backend and lockfile"
@@ -15,38 +15,45 @@ include = [
 keywords = ["tox", "poetry", "plugin"]
 readme = "README.md"
 classifiers = [
-  "Development Status :: 3 - Alpha",
+  "Development Status :: 4 - Beta",
   "Environment :: Plugins",
   "Framework :: tox",
   "Intended Audience :: Developers",
   "License :: OSI Approved :: MIT License",
   "Natural Language :: English",
   "Operating System :: OS Independent",
+  "Programming Language :: Python :: 3",
   "Programming Language :: Python :: 3.6",
   "Programming Language :: Python :: 3.7",
   "Programming Language :: Python :: 3.8",
+  "Programming Language :: Python :: 3.9",
   "Programming Language :: Python :: Implementation :: CPython",
 ]
 
 [tool.poetry.plugins.tox]
 poetry_installer = "tox_poetry_installer"
 
+[tool.poetry.extras]
+poetry = ["poetry"]
+
 [tool.poetry.dependencies]
-python = "^3.6"
-poetry = "^1.0.0"
+python = "^3.6.1"
+poetry = {version = "^1.0.0", optional = true}
 poetry-core = "^1.0.0"
-tox = "^2.3.0 || ^3.0.0"
+tox = "^3.8.0"
 
 [tool.poetry.dev-dependencies]
 bandit = "^1.6.2"
 black = { version = "^20.8b1", allow-prereleases = true }
+blacken-docs = "^1.8.0"
 ipython = { version = "^7.18.1", python = "^3.7" }
 mypy = "^0.782"
-pre-commit = {version = "^2.7.1", python = "^3.6.1"}
+pre-commit = "^2.7.1"
+pre-commit-hooks = "^3.3.0"
 pylint = "^2.4.4"
 pytest = "^6.0.2"
 pytest-cov = "^2.10.1"
-reorder-python-imports = {version = "^2.3.5", python = "^3.6.1"}
+reorder-python-imports = "^2.3.5"
 safety = "^1.9.0"
 toml = "^0.10.1"
 tox = "^3.20.0"

tox.ini

@@ -1,10 +1,13 @@
 [tox]
-envlist = py36, py37, py38, static, static-tests, security
+envlist = py36, py37, py38, py39, static, static-tests, security
 isolated_build = true
+skip_missing_interpreters = true
 
 [testenv]
 description = Run the tests
 require_locked_deps = true
+extras =
+    poetry
 locked_deps =
     pytest
     pytest-cov
@@ -19,23 +22,14 @@ platform = linux
 ignore_errors = true
 require_locked_deps = true
 locked_deps =
+    pre-commit
+    pre-commit-hooks
+    black
+    blacken-docs
+    reorder-python-imports
     pylint
     mypy
-    black
-    reorder-python-imports
-    pre-commit
-allowlist_externals =
-    bash
 commands =
-    black {toxinidir}/tox_poetry_installer/
-    # Oh man this is a doozy. If submodules are ever added to this plugin this will break, but I'm
-    # frustrated enough at this point that I'll need to take another look at it later to fix that.
-    # reorder-python-imports doesn't support handling directories on the CLI
-    # (https://github.com/asottile/reorder_python_imports/pull/76) and because the command is
-    # invoked directly (see comment below) we need file globbing to work around it.
-    # The "--unclassifiable-application-module" is a work around for reorder-python-imports not
-    # properly detecting the top-level module when run in a bash-wrapped command like this.
-    bash -c "reorder-python-imports {toxinidir}/tox_poetry_installer/*.py --unclassifiable-application-module tox_poetry_installer"
     pre-commit run --all-files
     pylint --rcfile {toxinidir}/.pylintrc {toxinidir}/tox_poetry_installer/
     mypy --ignore-missing-imports --no-strict-optional {toxinidir}/tox_poetry_installer/
@@ -49,19 +43,9 @@ require_locked_deps = true
 locked_deps =
     pylint
     mypy
-    black
-    reorder-python-imports
-allowlist_externals =
-    bash
 commands =
-    black {toxinidir}/tests/
-    # These bash-wrapped commands hurt my face, but these tools expect directories to be valid
-    # python modules, which the "tests/" directory is not. Since tox calls all commands directly
-    # (which is good) file globbing doesn't work. To make file globbing work they need to be wrapped
-    # in a bash call (which is bad).
-    bash -c "reorder-python-imports {toxinidir}/tests/*.py --unclassifiable-application-module tox_poetry_installer"
-    bash -c "pylint --rcfile {toxinidir}/.pylintrc {toxinidir}/tests/*.py"
-    bash -c "mypy --ignore-missing-imports --no-strict-optional {toxinidir}/tests/*.py"
+    pylint --rcfile {toxinidir}/.pylintrc {toxinidir}/tests/
+    mypy --ignore-missing-imports --no-strict-optional {toxinidir}/tests/
 
 [testenv:security]
 description = Security checks

tox_poetry_installer/__about__.py

@@ -1,7 +1,7 @@
 # pylint: disable=missing-docstring
 __title__ = "tox-poetry-installer"
 __summary__ = "Tox plugin to install Tox environment dependencies using the Poetry backend and lockfile"
-__version__ = "0.5.0"
+__version__ = "0.6.4"
 __url__ = "https://github.com/enpaul/tox-poetry-installer/"
 __license__ = "MIT"
 __authors__ = ["Ethan Paul <24588726+enpaul@users.noreply.github.com>"]

tox_poetry_installer/_poetry.py

@@ -0,0 +1,40 @@
+"""You've heard of vendoirization, now get ready for internal namespace shadowing
+
+Poetry is an optional dependency of this package explicitly to support the use case of having the
+plugin and the `poetry` package installed to the same python environment; this is most common in
+containers and/or CI. In this case there are two potential problems that can arise in this case:
+
+* The installation of the plugin overwrites the installed version of Poetry resulting in
+  compatibility issues.
+* Running `poetry install --no-dev`, when this plugin is in the dev-deps, results in poetry being
+  uninstalled from the environment.
+
+To support these edge cases, and more broadly to support not messing with a system package manager,
+the `poetry` package dependency is listed as optional dependency. This allows the plugin to be
+installed to the same environment as Poetry and import that same Poetry installation here.
+
+However, simply importing Poetry on the assumption that it is installed breaks another valid use
+case: having this plugin installed alongside Tox when not using a Poetry-based project. To account
+for this the imports in this module are isolated and the resultant import error that would result
+is converted to an internal error that can be caught by callers. Rather than importing this module
+at the module scope it is imported into function scope wherever Poetry components are needed. This
+moves import errors from load time to runtime which allows the plugin to be skipped if Poetry isn't
+installed and/or a more helpful error be raised within the Tox framework.
+"""
+# pylint: disable=unused-import
+import sys
+
+from tox_poetry_installer import exceptions
+
+
+try:
+    from poetry.factory import Factory
+    from poetry.installation.pip_installer import PipInstaller
+    from poetry.io.null_io import NullIO
+    from poetry.poetry import Poetry
+    from poetry.puzzle.provider import Provider
+    from poetry.utils.env import VirtualEnv
+except ImportError:
+    raise exceptions.PoetryNotInstalledError(
+        f"No version of Poetry could be imported under the current environment for '{sys.executable}'"
+    ) from None

tox_poetry_installer/constants.py

@@ -16,4 +16,4 @@ PEP508_VERSION_DELIMITERS: Tuple[str, ...] = ("~=", "==", "!=", ">", "<")
 
 # Prefix all reporter messages should include to indicate that they came from this module in the
 # console output.
-REPORTER_PREFIX = f"[{__about__.__title__}]:"
+REPORTER_PREFIX: str = f"{__about__.__title__}:"

tox_poetry_installer/exceptions.py

@@ -5,6 +5,8 @@ All exceptions should inherit from the common base exception :exc:`ToxPoetryInst
 ::
 
   ToxPoetryInstallerException
+   +-- SkipEnvironment
+   |    +-- PoetryNotInstalledError
    +-- LockedDepVersionConflictError
    +-- LockedDepNotFoundError
    +-- ExtraNotFoundError
@@ -17,6 +19,14 @@ class ToxPoetryInstallerException(Exception):
     """Error while installing locked dependencies to the test environment"""
 
 
+class SkipEnvironment(ToxPoetryInstallerException):
+    """Current environment does not meet preconditions and should be skipped by the plugin"""
+
+
+class PoetryNotInstalledError(SkipEnvironment):
+    """No version of Poetry could be imported from the current Python environment"""
+
+
 class LockedDepVersionConflictError(ToxPoetryInstallerException):
     """Locked dependencies cannot specify an alternate version for installation"""
 

tox_poetry_installer/hooks.py

@@ -4,25 +4,22 @@ All implementations of tox hooks are defined here, as well as any single-use hel
 specifically related to implementing the hooks (to keep the size/readability of the hook functions
 themselves manageable).
 """
-from typing import List
 from typing import Optional
 
-from poetry.core.packages import Package as PoetryPackage
-from poetry.factory import Factory as PoetryFactory
-from poetry.poetry import Poetry
-from tox import hookimpl
-from tox import reporter
+import tox
 from tox.action import Action as ToxAction
 from tox.config import Parser as ToxParser
 from tox.venv import VirtualEnv as ToxVirtualEnv
 
+from tox_poetry_installer import __about__
 from tox_poetry_installer import constants
 from tox_poetry_installer import exceptions
+from tox_poetry_installer import installer
 from tox_poetry_installer import utilities
 from tox_poetry_installer.datatypes import PackageMap
 
 
-@hookimpl
+@tox.hookimpl
 def tox_addoption(parser: ToxParser):
     """Add required configuration options to the tox INI file
 
@@ -30,6 +27,13 @@ def tox_addoption(parser: ToxParser):
     dependencies should be treated as locked or not.
     """
 
+    parser.add_argument(
+        "--require-poetry",
+        action="store_true",
+        dest="require_poetry",
+        help="Trigger a failure if Poetry is not available to Tox",
+    )
+
     parser.add_testenv_attribute(
         name="install_dev_deps",
         type="bool",
@@ -51,7 +55,7 @@ def tox_addoption(parser: ToxParser):
     )
 
 
-@hookimpl
+@tox.hookimpl
 def tox_testenv_install_deps(venv: ToxVirtualEnv, action: ToxAction) -> Optional[bool]:
     """Install the dependencies for the current environment
 
@@ -63,159 +67,86 @@ def tox_testenv_install_deps(venv: ToxVirtualEnv, action: ToxAction) -> Optional
     :param action: Tox action object
     """
 
-    if action.name == venv.envconfig.config.isolated_build_env:
-        # Skip running the plugin for the packaging environment. PEP-517 front ends can handle
-        # that better than we can, so let them do their thing. More to the point: if you're having
-        # problems in the packaging env that this plugin would solve, god help you.
-        reporter.verbosity1(
-            f"{constants.REPORTER_PREFIX} skipping isolated build env '{action.name}'"
-        )
+    try:
+        poetry = utilities.check_preconditions(venv, action)
+    except exceptions.SkipEnvironment as err:
+        if (
+            isinstance(err, exceptions.PoetryNotInstalledError)
+            and venv.envconfig.config.option.require_poetry
+        ):
+            venv.status = err.__class__.__name__
+            tox.reporter.error(str(err))
+            return False
+        tox.reporter.verbosity1(str(err))
         return None
 
+    tox.reporter.verbosity1(
+        f"{constants.REPORTER_PREFIX} Loaded project pyproject.toml from {poetry.file}"
+    )
+
+    virtualenv = utilities.convert_virtualenv(venv)
+
+    if not poetry.locker.is_fresh():
+        tox.reporter.warning(
+            f"The Poetry lock file is not up to date with the latest changes in {poetry.file}"
+        )
+
     try:
-        poetry = PoetryFactory().create_poetry(venv.envconfig.config.toxinidir)
-    except RuntimeError:
-        # Support running the plugin when the current tox project does not use Poetry for its
-        # environment/dependency management.
-        #
-        # ``RuntimeError`` is dangerous to blindly catch because it can be (and in Poetry's case,
-        # is) raised in many different places for different purposes.
-        reporter.verbosity1(
-            f"{constants.REPORTER_PREFIX} project does not use Poetry for env management, skipping installation of locked dependencies"
-        )
-        return None
-
-    reporter.verbosity1(
-        f"{constants.REPORTER_PREFIX} loaded project pyproject.toml from {poetry.file}"
-    )
-
-    package_map: PackageMap = {
-        package.name: package
-        for package in poetry.locker.locked_repository(True).packages
-    }
-
         if venv.envconfig.require_locked_deps and venv.envconfig.deps:
             raise exceptions.LockedDepsRequiredError(
                 f"Unlocked dependencies '{venv.envconfig.deps}' specified for environment '{venv.name}' which requires locked dependencies"
             )
 
-    # Handle the installation of any locked env dependencies from the lockfile
-    _install_env_dependencies(venv, poetry, package_map)
-
-    # Handle the installation of the package dependencies from the lockfile if the package is
-    # being installed to this venv; otherwise skip installing the package dependencies
-    if venv.envconfig.skip_install:
-        reporter.verbosity1(
-            f"{constants.REPORTER_PREFIX} env specifies 'skip_install = true', skipping installation of project package"
-        )
-        return venv.envconfig.require_locked_deps or None
-
-    if venv.envconfig.config.skipsdist:
-        reporter.verbosity1(
-            f"{constants.REPORTER_PREFIX} config specifies 'skipsdist = true', skipping installation of project package"
-        )
-        return venv.envconfig.require_locked_deps or None
-
-    _install_project_dependencies(venv, poetry, package_map)
-
-    return venv.envconfig.require_locked_deps or None
-
-
-def _install_env_dependencies(
-    venv: ToxVirtualEnv, poetry: Poetry, packages: PackageMap
-):
-    """Install the packages for a specified testenv
-
-    Processes the tox environment config, identifies any locked environment dependencies, pulls
-    them from the lockfile, and installs them to the virtual environment.
-
-    :param venv: Tox virtual environment to install the packages to
-    :param poetry: Poetry object the packages were sourced from
-    :param packages: Mapping of package names to the corresponding package object
-    """
-
-    dependencies: List[PoetryPackage] = []
-    for dep in venv.envconfig.locked_deps:
-        try:
-            dependencies += utilities.find_transients(packages, dep.lower())
-        except exceptions.ToxPoetryInstallerException as err:
-            venv.status = "lockfile installation failed"
-            reporter.error(f"{constants.REPORTER_PREFIX} {err}")
-            raise err
+        packages: PackageMap = {
+            package.name: package
+            for package in poetry.locker.locked_repository(True).packages
+        }
 
         if venv.envconfig.install_dev_deps:
-        reporter.verbosity1(
-            f"{constants.REPORTER_PREFIX} env specifies 'install_env_deps = true', including Poetry dev dependencies"
+            dev_deps = utilities.find_dev_deps(packages, virtualenv, poetry)
+            tox.reporter.verbosity1(
+                f"{constants.REPORTER_PREFIX} Identified {len(dev_deps)} development dependencies to install to env"
+            )
+        else:
+            dev_deps = []
+            tox.reporter.verbosity1(
+                f"{constants.REPORTER_PREFIX} Env does not install development dependencies, skipping"
             )
 
-        dev_dependencies = [
-            dep
-            for dep in poetry.locker.locked_repository(True).packages
-            if dep not in poetry.locker.locked_repository(False).packages
-        ]
-
-        reporter.verbosity1(
-            f"{constants.REPORTER_PREFIX} identified {len(dev_dependencies)} Poetry dev dependencies"
+        env_deps = utilities.find_additional_deps(
+            packages, virtualenv, poetry, venv.envconfig.locked_deps
         )
 
-        dependencies = list(set(dev_dependencies + dependencies))
-
-    reporter.verbosity1(
-        f"{constants.REPORTER_PREFIX} identified {len(dependencies)} total dependencies from {len(venv.envconfig.locked_deps)} locked env dependencies"
+        tox.reporter.verbosity1(
+            f"{constants.REPORTER_PREFIX} Identified {len(env_deps)} environment dependencies to install to env"
         )
 
-    reporter.verbosity0(
-        f"{constants.REPORTER_PREFIX} ({venv.name}) installing {len(dependencies)} env dependencies from lockfile"
+        if not venv.envconfig.skip_install and not venv.envconfig.config.skipsdist:
+            project_deps = utilities.find_project_deps(
+                packages, virtualenv, poetry, venv.envconfig.extras
             )
-    utilities.install_to_venv(poetry, venv, dependencies)
-
-
-def _install_project_dependencies(
-    venv: ToxVirtualEnv, poetry: Poetry, packages: PackageMap
-):
-    """Install the dependencies of the project package
-
-    Install all primary dependencies of the project package.
-
-    :param venv: Tox virtual environment to install the packages to
-    :param poetry: Poetry object the packages were sourced from
-    :param packages: Mapping of package names to the corresponding package object
-    """
-    reporter.verbosity1(
-        f"{constants.REPORTER_PREFIX} performing installation of project dependencies"
+            tox.reporter.verbosity1(
+                f"{constants.REPORTER_PREFIX} Identified {len(project_deps)} project dependencies to install to env"
+            )
+        else:
+            project_deps = []
+            tox.reporter.verbosity1(
+                f"{constants.REPORTER_PREFIX} Env does not install project package, skipping"
             )
-
-    base_dependencies: List[PoetryPackage] = [
-        packages[item.name]
-        for item in poetry.package.requires
-        if not item.is_optional()
-    ]
-
-    extra_dependencies: List[PoetryPackage] = []
-    for extra in venv.envconfig.extras:
-        try:
-            extra_dependencies += [
-                packages[item.name] for item in poetry.package.extras[extra]
-            ]
-        except KeyError:
-            raise exceptions.ExtraNotFoundError(
-                f"Environment '{venv.name}' specifies project extra '{extra}' which was not found in the lockfile"
-            ) from None
-
-    dependencies: List[PoetryPackage] = []
-    for dep in base_dependencies + extra_dependencies:
-        try:
-            dependencies += utilities.find_transients(packages, dep.name.lower())
     except exceptions.ToxPoetryInstallerException as err:
-            venv.status = "lockfile installation failed"
-            reporter.error(f"{constants.REPORTER_PREFIX} {err}")
+        venv.status = err.__class__.__name__
+        tox.reporter.error(f"{constants.REPORTER_PREFIX} {err}")
+        return False
+    except Exception as err:
+        venv.status = "InternalError"
+        tox.reporter.error(f"{constants.REPORTER_PREFIX} Internal plugin error: {err}")
         raise err
 
-    reporter.verbosity1(
-        f"{constants.REPORTER_PREFIX} identified {len(dependencies)} total dependencies from {len(poetry.package.requires)} project dependencies"
+    dependencies = dev_deps + env_deps + project_deps
+    action.setactivity(
+        __about__.__title__,
+        f"Installing {len(dependencies)} dependencies from Poetry lock file",
     )
+    installer.install(poetry, venv, dependencies)
 
-    reporter.verbosity0(
-        f"{constants.REPORTER_PREFIX} ({venv.name}) installing {len(dependencies)} project dependencies from lockfile"
-    )
-    utilities.install_to_venv(poetry, venv, dependencies)
+    return venv.envconfig.require_locked_deps or None

tox_poetry_installer/installer.py

@@ -0,0 +1,53 @@
+"""Funcationality for performing virtualenv installation"""
+# Silence this one globally to support the internal function imports for the proxied poetry module.
+# See the docstring in 'tox_poetry_installer._poetry' for more context.
+# pylint: disable=import-outside-toplevel
+import typing
+from typing import Sequence
+from typing import Set
+
+import tox
+from poetry.core.packages import Package as PoetryPackage
+from tox.venv import VirtualEnv as ToxVirtualEnv
+
+from tox_poetry_installer import constants
+from tox_poetry_installer import utilities
+
+if typing.TYPE_CHECKING:
+    from tox_poetry_installer import _poetry
+
+
+def install(
+    poetry: "_poetry.Poetry", venv: ToxVirtualEnv, packages: Sequence[PoetryPackage]
+):
+    """Install a bunch of packages to a virtualenv
+
+    :param poetry: Poetry object the packages were sourced from
+    :param venv: Tox virtual environment to install the packages to
+    :param packages: List of packages to install to the virtual environment
+    """
+    from tox_poetry_installer import _poetry
+
+    tox.reporter.verbosity1(
+        f"{constants.REPORTER_PREFIX} Installing {len(packages)} packages to environment at {venv.envconfig.envdir}"
+    )
+
+    pip = _poetry.PipInstaller(
+        env=utilities.convert_virtualenv(venv),
+        io=_poetry.NullIO(),
+        pool=poetry.pool,
+    )
+
+    installed: Set[PoetryPackage] = set()
+
+    for dependency in packages:
+        if dependency not in installed:
+            tox.reporter.verbosity2(
+                f"{constants.REPORTER_PREFIX} Installing {dependency}"
+            )
+            pip.install(dependency)
+            installed.add(dependency)
+        else:
+            tox.reporter.verbosity2(
+                f"{constants.REPORTER_PREFIX} Skipping {dependency}, already installed"
+            )

tox_poetry_installer/utilities.py

@@ -1,85 +1,234 @@
 """Helper utility functions, usually bridging Tox and Poetry functionality"""
+# Silence this one globally to support the internal function imports for the proxied poetry module.
+# See the docstring in 'tox_poetry_installer._poetry' for more context.
+# pylint: disable=import-outside-toplevel
+import typing
 from pathlib import Path
+from typing import List
 from typing import Sequence
 from typing import Set
+from typing import Union
 
+import tox
+from poetry.core.packages import Dependency as PoetryDependency
 from poetry.core.packages import Package as PoetryPackage
-from poetry.installation.pip_installer import PipInstaller as PoetryPipInstaller
-from poetry.io.null_io import NullIO as PoetryNullIO
-from poetry.poetry import Poetry
-from poetry.puzzle.provider import Provider as PoetryProvider
-from poetry.utils.env import VirtualEnv as PoetryVirtualEnv
-from tox import reporter
+from tox.action import Action as ToxAction
 from tox.venv import VirtualEnv as ToxVirtualEnv
 
 from tox_poetry_installer import constants
 from tox_poetry_installer import exceptions
 from tox_poetry_installer.datatypes import PackageMap
 
+if typing.TYPE_CHECKING:
+    from tox_poetry_installer import _poetry
 
-def install_to_venv(
-    poetry: Poetry, venv: ToxVirtualEnv, packages: Sequence[PoetryPackage]
-):
-    """Install a bunch of packages to a virtualenv
 
-    :param poetry: Poetry object the packages were sourced from
-    :param venv: Tox virtual environment to install the packages to
-    :param packages: List of packages to install to the virtual environment
-    """
-
-    reporter.verbosity1(
-        f"{constants.REPORTER_PREFIX} Installing {len(packages)} packages to environment at {venv.envconfig.envdir}"
+def check_preconditions(venv: ToxVirtualEnv, action: ToxAction) -> "_poetry.Poetry":
+    """Check that the local project environment meets expectations"""
+    # Skip running the plugin for the provisioning environment. The provisioned environment,
+    # for alternative Tox versions and/or the ``requires`` meta dependencies is specially
+    # handled by Tox and is out of scope for this plugin. Since one of the ways to install this
+    # plugin in the first place is via the Tox provisioning environment, it quickly becomes a
+    # chicken-and-egg problem.
+    if action.name == venv.envconfig.config.provision_tox_env:
+        raise exceptions.SkipEnvironment(
+            f"Skipping Tox provisioning env '{action.name}'"
         )
 
-    installer = PoetryPipInstaller(
-        env=PoetryVirtualEnv(path=Path(venv.envconfig.envdir)),
-        io=PoetryNullIO(),
-        pool=poetry.pool,
+    # Skip running the plugin for the packaging environment. PEP-517 front ends can handle
+    # that better than we can, so let them do their thing. More to the point: if you're having
+    # problems in the packaging env that this plugin would solve, god help you.
+    if action.name == venv.envconfig.config.isolated_build_env:
+        raise exceptions.SkipEnvironment(
+            f"Skipping isolated packaging build env '{action.name}'"
         )
 
-    for dependency in packages:
-        reporter.verbosity1(f"{constants.REPORTER_PREFIX} installing {dependency}")
-        installer.install(dependency)
-
-
-def find_transients(packages: PackageMap, dependency_name: str) -> Set[PoetryPackage]:
-    """Using a poetry object identify all dependencies of a specific dependency
-
-    :param poetry: Populated poetry object which can be used to build a populated locked
-                   repository object.
-    :param dependency_name: Bare name (without version) of the dependency to fetch the transient
-                            dependencies of.
-    :returns: List of packages that need to be installed for the requested dependency.
-
-    .. note:: The package corresponding to the dependency named by ``dependency_name`` is included
-              in the list of returned packages.
-    """
+    from tox_poetry_installer import _poetry
 
     try:
+        return _poetry.Factory().create_poetry(venv.envconfig.config.toxinidir)
+    # Support running the plugin when the current tox project does not use Poetry for its
+    # environment/dependency management.
+    #
+    # ``RuntimeError`` is dangerous to blindly catch because it can be (and in Poetry's case,
+    # is) raised in many different places for different purposes.
+    except RuntimeError:
+        raise exceptions.SkipEnvironment(
+            "Project does not use Poetry for env management, skipping installation of locked dependencies"
+        ) from None
 
-        def find_deps_of_deps(name: str, transients: PackageMap):
-            if name in PoetryProvider.UNSAFE_PACKAGES:
-                reporter.warning(
-                    f"{constants.REPORTER_PREFIX} installing package '{name}' using Poetry is not supported; skipping installation of package '{name}'"
+
+def convert_virtualenv(venv: ToxVirtualEnv) -> "_poetry.VirtualEnv":
+    """Convert a Tox venv to a Poetry venv
+
+    :param venv: Tox ``VirtualEnv`` object representing a tox virtual environment
+    :returns: Poetry ``VirtualEnv`` object representing a poetry virtual environment
+    """
+    from tox_poetry_installer import _poetry
+
+    return _poetry.VirtualEnv(path=Path(venv.envconfig.envdir))
+
+
+def identify_transients(
+    dep: Union[PoetryDependency, str],
+    packages: PackageMap,
+    venv: "_poetry.VirtualEnv",
+    allow_missing: Sequence[str] = (),
+) -> List[PoetryPackage]:
+    """Using a pool of packages, identify all transient dependencies of a given package name
+
+    :param dep: Either the Poetry dependency or the dependency's bare package name to recursively
+                identify the transient dependencies of
+    :param packages: All packages from the lockfile to use for identifying dependency relationships.
+    :param venv: Poetry virtual environment to use for package compatibility checks
+    :param allow_missing: Sequence of package names to allow to be missing from the lockfile. Any
+                          packages that are not found in the lockfile but their name appears in this
+                          list will be silently skipped from installation.
+    :returns: List of packages that need to be installed for the requested dependency.
+
+    .. note:: The package corresponding to the dependency specified by the ``dep`` parameter will
+              be included in the returned list of packages.
+    """
+    from tox_poetry_installer import _poetry
+
+    transients: List[PoetryPackage] = []
+    searched: Set[str] = set()
+
+    def _deps_of_dep(transient: PoetryDependency):
+        searched.add(transient.name)
+
+        if venv.is_valid_for_marker(transient.marker):
+            for requirement in packages[transient.name].requires:
+                if requirement.name not in searched:
+                    _deps_of_dep(requirement)
+            tox.reporter.verbosity2(
+                f"{constants.REPORTER_PREFIX} Including {transient} for installation"
             )
+            transients.append(packages[transient.name])
         else:
-                transients[name] = packages[name]
-                for dep in packages[name].requires:
-                    if dep.name not in transients.keys():
-                        find_deps_of_deps(dep.name, transients)
+            tox.reporter.verbosity2(
+                f"{constants.REPORTER_PREFIX} Skipping {transient}: package requires {transient.marker}"
+            )
 
-        transients: PackageMap = {}
-        find_deps_of_deps(packages[dependency_name].name, transients)
+    try:
+        if isinstance(dep, str):
+            dep = packages[dep].to_dependency()
+
+        _deps_of_dep(dep)
+    except KeyError as err:
+        dep_name = err.args[0]
+
+        if dep_name in _poetry.Provider.UNSAFE_PACKAGES:
+            tox.reporter.warning(
+                f"{constants.REPORTER_PREFIX} Installing package '{dep_name}' using Poetry is not supported and will be skipped"
+            )
+            tox.reporter.verbosity2(
+                f"{constants.REPORTER_PREFIX} Skipping {dep_name}: designated unsafe by Poetry"
+            )
+            return []
+
+        if dep_name in allow_missing:
+            tox.reporter.verbosity2(
+                f"{constants.REPORTER_PREFIX} Skipping {dep_name}: package is allowed to be unlocked"
+            )
+            return []
 
-        return set(transients.values())
-    except KeyError:
         if any(
-            delimiter in dependency_name
-            for delimiter in constants.PEP508_VERSION_DELIMITERS
+            delimiter in dep_name for delimiter in constants.PEP508_VERSION_DELIMITERS
         ):
             raise exceptions.LockedDepVersionConflictError(
-                f"Locked dependency '{dependency_name}' cannot include version specifier"
+                f"Locked dependency '{dep_name}' cannot include version specifier"
             ) from None
+
         raise exceptions.LockedDepNotFoundError(
-            f"No version of locked dependency '{dependency_name}' found in the project lockfile"
+            f"No version of locked dependency '{dep_name}' found in the project lockfile"
         ) from None
+
+    return transients
+
+
+def find_project_deps(
+    packages: PackageMap,
+    venv: "_poetry.VirtualEnv",
+    poetry: "_poetry.Poetry",
+    extras: Sequence[str] = (),
+) -> List[PoetryPackage]:
+    """Find the root project dependencies
+
+    Recursively identify the dependencies of the root project package
+
+    :param packages: Mapping of all locked package names to their corresponding package object
+    :param venv: Poetry virtual environment to use for package compatibility checks
+    :param poetry: Poetry object for the current project
+    :param extras: Sequence of extra names to include the dependencies of
+    """
+
+    base_deps: List[PoetryPackage] = [
+        packages[item.name]
+        for item in poetry.package.requires
+        if not item.is_optional()
+    ]
+
+    extra_deps: List[PoetryPackage] = []
+    for extra in extras:
+        tox.reporter.verbosity1(
+            f"{constants.REPORTER_PREFIX} Processing project extra '{extra}'"
+        )
+        try:
+            extra_deps += [packages[item.name] for item in poetry.package.extras[extra]]
+        except KeyError:
+            raise exceptions.ExtraNotFoundError(
+                f"Environment specifies project extra '{extra}' which was not found in the lockfile"
+            ) from None
+
+    dependencies: List[PoetryPackage] = []
+    for dep in base_deps + extra_deps:
+        dependencies += identify_transients(
+            dep.name.lower(), packages, venv, allow_missing=[poetry.package.name]
+        )
+
+    return dependencies
+
+
+def find_additional_deps(
+    packages: PackageMap,
+    venv: "_poetry.VirtualEnv",
+    poetry: "_poetry.Poetry",
+    dep_names: Sequence[str],
+) -> List[PoetryPackage]:
+    """Find additional dependencies
+
+    Recursively identify the dependencies of an arbitrary list of package names
+
+    :param packages: Mapping of all locked package names to their corresponding package object
+    :param venv: Poetry virtual environment to use for package compatibility checks
+    :param poetry: Poetry object for the current project
+    :param dep_names: Sequence of additional dependency names to recursively find the transient
+                      dependencies for
+    """
+    deps: List[PoetryPackage] = []
+    for dep_name in dep_names:
+        deps += identify_transients(
+            dep_name.lower(), packages, venv, allow_missing=[poetry.package.name]
+        )
+
+    return deps
+
+
+def find_dev_deps(
+    packages: PackageMap, venv: "_poetry.VirtualEnv", poetry: "_poetry.Poetry"
+) -> List[PoetryPackage]:
+    """Find the dev dependencies
+
+    Recursively identify the Poetry dev dependencies
+
+    :param packages: Mapping of all locked package names to their corresponding package object
+    :param venv: Poetry virtual environment to use for package compatibility checks
+    :param poetry: Poetry object for the current project
+    """
+    return find_additional_deps(
+        packages,
+        venv,
+        poetry,
+        poetry.pyproject.data["tool"]["poetry"].get("dev-dependencies", {}).keys(),
+    )