Rewrite usage examples section into reference section

Fixes #20
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Ethan Paul 2020-11-12 18:58:50 -05:00
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@ -15,7 +15,10 @@ dependencies to be installed using [Poetry](https://python-poetry.org/) from its
* [Installation](#installation) * [Installation](#installation)
* [Quick Start](#quick-start) * [Quick Start](#quick-start)
* [Usage Examples](#usage-examples) * [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) * [Known Drawbacks and Problems](#known-drawbacks-and-problems)
* [Why would I use this?](#why-would-i-use-this) (What problems does this solve?) * [Why would I use this?](#why-would-i-use-this) (What problems does this solve?)
* [Developing](#developing) * [Developing](#developing)
@ -98,143 +101,92 @@ Alternatively, to quickly install all Poetry dev-dependencies to a Tox environme
one Tox is testing) will always be installed from the lockfile. one Tox is testing) will always be installed from the lockfile.
## Usage Examples ## Reference and Usage
After installing the plugin to a project your Tox automation is already benefiting from the ### Config Option Reference
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? 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.
Let's use an example `tox.ini` file, below, that defines two environments: the main `testenv` for **NOTE:** Environment settings applied to the main `testenv` environment will be
running the project tests and `testenv:check` for running some other helpful tools: 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
```ini ```ini
[tox] [tox]
envlist = py37, static envlist = py, foo, bar, baz
isolated_build = true 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] [testenv]
description = Run the tests description = Some very cool 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:
```ini
[testenv:check]
description = Static formatting and quality enforcement
require_locked_deps = true require_locked_deps = true
deps = locked_deps =
pylint >=2.4.4,<2.6.0 pytest
mypy == 0.770 pytest-cov
black --pre
commands = ... commands = ...
```
Running Tox using this config gives us this error: # 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]
tox_poetry_installer.LockedDepVersionConflictError: Locked dependency 'pylint >=2.4.4,<2.6.0' cannot include version specifier description = FOObarbaz
``` skip_install = true
This is because we told the Tox environment to require all dependencies 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 gets conflicting
information it errors. We can fix this by simply removing all version specifiers from the
environment dependency list:
```ini
[testenv:check]
description = Static formatting and quality enforcement
require_locked_deps = true require_locked_deps = true
deps = locked_deps =
pylint 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 mypy
pylint
deps =
black black
commands = ... commands = ...
```
Now all the dependencies will be installed from the lockfile. If Poetry updates the lockfile with # This environment requires locked dependencies but does not specify any. Instead it specifies the
a new version then that updated version will be automatically installed when the Tox environment is # "install_dev_deps = true" option which will cause all of the Poetry dev-dependencies to be
recreated. # installed from the lockfile.
[testenv:baz]
Now let's look at the `testenv` environment. Let's make the same changes to the `testenv` description = foobarBAZ
environment that we made to `testenv:check` above; remove the PyTest version and add install_dev_deps = true
`require_locked_deps = true`. Then imagine that we want to add the
[Requests](https://requests.readthedocs.io/en/master/) library to the test environment: we
can add `requests` as a dependency of the test environment, but this will cause an error:
```ini
[testenv]
description = Run the tests
require_locked_deps = true require_locked_deps = true
deps =
pytest
requests
commands = ... commands = ...
``` ```
Running Tox with this config gives us this error:
```
tox_poetry_installer.LockedDepNotFoundError: No version of locked dependency 'requests' found in the project lockfile
```
This is because `requests` is not in our lockfile yet. Tox will refuse to install a dependency
that isn't in the lockfile to an an environment that specifies `require_locked_deps = true`. We
can fix this by running `poetry add requests --dev` to add it to the lockfile.
Now let's combine dependencies from the lockfile with dependencies that are
specified in-line in the Tox environment configuration.
[This isn't generally recommended](#why-would-i-use-this), but it is 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 specifier to the `requests`
entry in the dependency list:
```ini
[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 the `pytest` entry in the
dependency list:
```ini
[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.
## Known Drawbacks and Problems ## Known Drawbacks and Problems