|
||
---|---|---|
tests | ||
.coveragerc | ||
.gitignore | ||
.pre-commit-config.yaml | ||
.pylintrc | ||
CODE_OF_CONDUCT.md | ||
LICENSE.md | ||
Makefile | ||
poetry.lock | ||
pyproject.toml | ||
README.md | ||
tox_poetry_installer.py | ||
tox.ini |
tox-poetry-installer
A plugin for Tox that allows test environment dependencies to be installed using Poetry using its lockfile.
⚠️ This project is alpha software and should not be used in a production capacity ⚠️
Documentation
- Installation
- Quick Start
- Usage
- Known Drawbacks and Problems
- Why would I use this? (What problems does this solve?)
- Developing
- Contributing
- Roadmap
Related resources:
Installation
Add the plugin as a development dependency a project using Poetry:
~ $: poetry add tox-poetry-installer --dev
Confirm that the plugin is installed, and Tox recognizes it, 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-0.2.0 at .venv/lib64/python3.8/site-packages/tox_poetry_installer.py
If using in a CI/automation environment using Pip, ensure that the plugin is installed to the same environment as Tox:
# 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
To require a Tox environment install all it's dependencies from the Poetry lockfile, add the
require_locked_deps = true
option to the environment configuration and remove all version
specifiers from the dependency list. The versions to install will be taken from the lockfile
directly:
[testenv]
description = Run the tests
require_locked_deps = true
deps =
pytest
pytest-cov
black
pylint
mypy
commands = ...
To require specific dependencies be installed from the Poetry lockfile, and let the rest be
installed using the default Tox installation method, add the suffix @poetry
to the dependencies.
In the example below the pytest
, pytest-cov
, and black
dependencies will be installed using
the lockfile while pylint
and mypy
will be installed using the versions specified here:
[testenv]
description = Run the tests
require_locked_deps = true
deps =
pytest@poetry
pytest-cov@poetry
black@poetry
pylint >=2.5.0
mypy == 0.770
commands = ...
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.
Usage
After installing the plugin to a project, your Tox automation is already benefiting from the lockfile: when Tox installs your project package to one of your environments, all the dependencies of your project package will be installed using the versions specified in the lockfile. This happens automatically and requires no configuration changes.
But what about the rest of your Tox environment dependencies?
Let's use an example tox.ini
file, below, that defines two environments: the main testenv
for
running the project tests and testenv:check
for running some other helpful checks:
[tox]
envlist = py37, static
isolated_build = true
[testenv]
description = Run the tests
deps =
pytest == 5.3.0
commands = ...
[testenv:check]
description = Static formatting and quality enforcement
deps =
pylint >=2.4.4,<2.6.0
mypy == 0.770
black --pre
commands = ...
Let's focus on the testenv:check
environment first. In this project there's no reason that any
of these tools should be a different version than what a human developer is using when installing
from the lockfile. We can require that these dependencies be installed from the lockfile by adding
the option require_locked_deps = true
to the environment config, but this will cause an error:
[testenv:check]
description = Static formatting and quality enforcement
require_locked_deps = true
deps =
pylint >=2.4.4,<2.6.0
mypy == 0.770
black --pre
commands = ...
Running Tox using this config gives us this error:
tox_poetry_installer.LockedDepVersionConflictError: Locked dependency 'pylint >=2.4.4,<2.6.0' cannot include version specifier
This is because we told the Tox environment to require all dependencies to be locked, but then also
specified a specific version constraint for Pylint. With the require_locked_deps = true
setting
Tox expects all dependencies to take their version from the lockfile, so when it got conflicting
information it errors. We can fix this by simply removing all version specifiers from the
environment dependency list:
[testenv:check]
description = Static formatting and quality enforcement
require_locked_deps = true
deps =
pylint
mypy
black
commands = ...
Now all the dependencies will be installed from the lockfile. If Poetry updates the lockfile with a new version then that updated version will be automatically installed when the Tox environment is recreated.
Now let's look at the testenv
environment. Let's make the same changes to the testenv
environment that we made to testenv:check
above; remove the PyTest version and add
require_locked_deps = true
. Then imagine that we want to add a new (made up) tool the test
environment called crash_override
to the environment: we can add crash-override
as a dependency
of the test environment, but this will cause an error:
[testenv]
description = Run the tests
require_locked_deps = true
deps =
pytest
crash-override
commands = ...
Running Tox with this config gives us this error:
tox_poetry_installer.LockedDepNotFoundError: No version of locked dependency 'crash-override' found in the project lockfile
This is because crash-override
is not in our lockfile. Tox will refuse to install a dependency
that isn't in the lockfile to an an environment that specifies require_locked_deps = true
. We
could fix this (if crash-override
was a real package) by running
poetry add crash-override --dev
to add it to the lockfile.
Now let's combine dependencies from the lockfile ("locked dependencies") with dependencies that are
specified inline in the environment configuration ("unlocked dependencies").
This isn't generally recommended of course, but it's a valid use case and
fully supported by this plugin. Let's modify the testenv
configuration to install PyTest from the
lockfile but then install an older version of the
Requests library.
The first thing to do is remove the require_locked_deps = true
setting so that we can install
Requests as an unlocked dependency. Then we can add our version of requests to the dependency list:
[testenv]
description = Run the tests
deps =
pytest
requests >=2.2.0,<2.10.0
commands = ...
However we still want pytest
to be installed from the lockfile, so the final step is to tell Tox
to install it from the lockfile by adding the suffix @poetry
to it:
[testenv]
description = Run the tests
deps =
pytest@poetry
requests >=2.2.0,<2.10.0
commands = ...
Now when the testenv
environment is created it will install PyTest (and all of its dependencies)
from the lockfile while it will install Requests (and all of its dependencies) using the default
Tox installation backend using Pip.
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
pip_pre
downloadcache
(deprecated)download
indexserver
usedevelop
-
The
extras
setting intox.ini
does not work. Optional dependencies of the project package will not be installed to Tox environments. (See the road map) -
The plugin currently depends on
poetry<1.1.0
. This can be a different version than Poetry being used for actual project development. (See the road map) -
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; the list of dependencies that cannot be installed from the lockfile can be found here. 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 lists what dependencies are installed, the versions of those dependencies, and additional metadata that the package manager can use 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 that a developer is.
Poetry is a project dependency manager for Python projects, and as such it creates and manages a lockfile so that its users can benefit from all the features described above. Tox is an automation tool that allows Python developers to run tests suites, perform builds, and automate tasks within self contained Python virtual environments. To make these environments useful, Tox supports installing per-environment dependencies. 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 to install the PEP-508 compliant dependencies to a test environment. A more robust way to do this is to install dependencies directly from the lockfile so that the version installed to the Tox environment always matches the version Poetry specifies. This plugin overwrites the default Tox dependency installation behavior and replaces it with a Poetry-based installation using the dependency metadata from the lockfile.
The Problem
Environment dependencies for a Tox environment are usually done in PEP-508 format like the below example
# tox.ini
...
[testenv]
description = Some very cool tests
deps =
foo == 1.2.3
bar >=1.3,<2.0
baz
...
Perhaps these dependencies are also useful during development, so they can be added to the Poetry environment using this command:
poetry add foo==1.2.3 bar>=1.3,<2.0 baz --dev
However there are three potential problems that could arise from each of these environment dependencies that would only appear in the Tox environment and not in the Poetry environment:
-
The
foo
dependency is pinned to a specific version: let's imagine a security vulnerability is discovered infoo
and the maintainers release version1.2.4
to fix it. A developer can runpoetry remove foo && poetry add foo^1.2
to get the new version, but the Tox environment is left unchanged. The developer environment specified by the lockfile is now patched against the vulnerability, but the Tox environment is not. -
The
bar
dependency specifies a dynamic range: a dynamic range allows a range of versions to be installed, but the lockfile will have an exact version specified so that the Poetry environment is reproducible; this allows versions to be updated withpoetry update
rather than with theremove
andadd
used above. If the maintainers ofbar
release version1.6.0
then the Tox environment will install it because it is valid for the specified version range, meanwhile the Poetry environment will continue to install the version from the lockfile untilpoetry update bar
explicitly updates it. The development environment is now has a different version ofbar
than the Tox environment. -
The
baz
dependency is unpinned: unpinned dependencies are generally a bad idea, but here it can cause real problems. Poetry will interpret an unbound dependency using the carrot requirement but Pip (via Tox) will interpret it as a wildcard. If the latest version ofbaz
is1.0.0
thenpoetry add baz
will result in a constraint ofbaz>=1.0.0,<2.0.0
while the Tox environment will have a constraint ofbaz==*
. The Tox environment can now install an incompatible version ofbaz
that cannot be easily caught usingpoetry update
.
All of these problems can apply not only to the dependencies specified for a Tox environment, but also to the dependencies of those dependencies, and so on.
The Solution
This plugin requires that all dependencies specified for all Tox environments be unbound with no version constraint specified at all. This seems counter-intuitive given the problems outlined above, but what it allows the plugin to do is offload all version management to Poetry.
On initial inspection, the environment below appears less stable than the one presented above because it does not specify any versions for its dependencies:
# tox.ini
...
[testenv]
description = Some very cool tests
deps =
foo
bar
baz
...
However with the tox-poetry-installer
plugin installed this instructs Tox to install these
dependencies using 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 dependency versions, Tox will automatically install these new versions without needing
any changes to the configuration.
All dependencies are specified in one place (the lockfile) and dependency version management is handled by a tool dedicated to that task (Poetry).
Developing
This project requires Poetry-1.0+, see the installation instructions here.
# Clone the repository...
# ...over HTTPS
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
# Install pre-commit hooks
poetry run pre-commit install
# Run tests and static analysis
poetry run tox
Contributing
All project contributors and participants are expected to adhere to the Contributor Covenant Code of Conduct, Version 2.
The devel
branch has the latest (potentially unstable) changes. The
tagged versions correspond to the
releases on PyPI.
- To report a bug, request a feature, or ask for assistance, please open an issue on the Github repository.
- To report a security concern or code of conduct violation, please contact the project author directly at ethan dot paul at enp dot one.
- To submit an update, please fork the repository and open a pull request.
Roadmap
This project is under active development and is classified as alpha software, not yet ready usage in production systems.
- Beta classification will be assigned when the initial feature set is finalized
- Stable classification will be assigned when the test suite covers an acceptable number of use cases
Path to Beta
- Verify that primary package dependencies (from the
.package
env) are installed correctly using the Poetry backend. - Support the
extras
Tox configuration option - Add per-environment Tox configuration option to fall back to default installation backend.
- Add detection of a changed lockfile to automatically trigger a rebuild of Tox environments when necessary.
- Add warnings when an unsupported Tox configuration option is detected while using the Poetry backend.
- Add trivial tests to ensure the project metadata is consistent between the pyproject.toml and the module constants.
- Update to use poetry-core Tox configuration option) and improve robustness of the Tox and Poetry module imports to avoid potentially breaking API changes in upstream packages.
- Find and implement a way to mitigate the Poetry UNSAFE_DEPENDENCIES bug.
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
- Add Github Actions based CI
- Add CI for CPython, PyPy, and Conda
- Add CI for Linux and Windows