Allow this project to bootstrap itself with tox

.github/workflows/test-tox-plugin.yml

@@ -0,0 +1,17 @@
+on: [push, pull_request]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: [ '3.6', '3.7', '3.8', '3.9' ]
+    name: Tox plugin - Python ${{ matrix.python-version }}
+    steps:
+      - uses: actions/checkout@v2
+      - name: Setup python
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - run: python -m pip install tox
+      - run: python -m pip install -e .
+      - run: python -m tox -c tests/tox-plugin/tox.ini

.gitignore

@@ -0,0 +1,4 @@
+dist/
+build/
+.eggs/
+*.egg-info/

README.md

@@ -73,3 +73,37 @@ To use the keyring backend:
    * `keyrings.gauth.GooglePyPIAuth (priority: 9)`
    * `keyring.backends.chainer.ChainerBackend (priority: 10)`
    * `keyring.backends.fail.Keyring (priority: 0)`
+
+## Usage with other tools
+
+### Usage with `tox`
+
+The [`tox` tool](https://pypi.org/project/tox/) is a testing and automation tool.
+
+Because the credential helper needs to be installed _before_ any private
+dependencies are installed, it needs to be bootstrapped into the `tox`
+environment via a plugin.
+
+To do this, specify the `keyrings.google-artifactregistry-auth` package via the
+[`requires`](https://tox.readthedocs.io/en/latest/config.html#conf-requires)
+requirement in your `tox.ini` file:
+
+    ```
+    [tox]
+    envlist = py
+    requires = keyrings.google-artifactregistry-auth
+    ```
+
+You can then configure your `tox.ini` file to use the Artifact Registry repo as
+an extra index, and specify both public and private dependencies:
+
+    ```
+    [testenv]
+    setenv =
+        PIP_EXTRA_INDEX_URL = https://[REGION]-pypi.pkg.dev/[PROJECT_ID]/[REPOSITORY]/simple
+    deps =
+        # samplepackage will be installed directly from PyPI
+        samplepackage
+        # mypackage will be installed from the Artifact Registry repository
+        mypackage
+    ```

google_artifactregistry_auth/__init__.py

@@ -0,0 +1 @@
+__version__ = "0.0.2"

google_artifactregistry_auth/tox_bootstrap.py

@@ -0,0 +1,17 @@
+import pluggy
+
+import google_artifactregistry_auth
+
+hookimpl = pluggy.HookimplMarker("tox")
+
+
+@hookimpl
+def tox_testenv_install_deps(venv, action):
+    venv._install(
+        [
+            "keyrings.google-artifactregistry-auth=={}".format(
+                google_artifactregistry_auth.__version__
+            )
+        ],
+        action=action,
+    )

pyproject.toml

@@ -0,0 +1,3 @@
+[build-system]
+# Minimum requirements for the build system to execute.
+requires = ["setuptools>=46.4.0", "wheel"]

setup.cfg

@@ -1,7 +1,7 @@
 [metadata]
 license_file = LICENSE
 name = keyrings.google-artifactregistry-auth
-version = 0.0.2
+version = attr: google_artifactregistry_auth.__version__
 author = Megan Kuo
 author_email = megankuo@google.com
 description = Keyring backend for Google Auth tokens
@@ -23,6 +23,7 @@ install_requires =
 	keyring
 	google-auth
 	requests
+	pluggy
 setup_requires = setuptools_scm[toml] >= 3.4.1
 
 [options.extras_require]
@@ -40,4 +41,5 @@ testing =
 [options.entry_points]
 keyring.backends =
 	Google Auth = keyrings.gauth
-
+tox =
+	tox_bootstrap = google_artifactregistry_auth.tox_bootstrap

tests/tox-plugin/setup.py

@@ -0,0 +1,3 @@
+from setuptools import setup
+
+setup()

tests/tox-plugin/tox.ini

@@ -0,0 +1,6 @@
+[tox]
+envlist = py
+requires = keyrings.google-artifactregistry-auth
+
+[testenv]
+commands = python -m pip show keyrings.google-artifactregistry-auth