test: Add tox testing

Add `tox.ini` config with supported versions, and a new tox CI
workflow to run tox tests on master branch changes. This is "expensive"
so we may consider limiting execution further.

.github/workflows/tox.yaml

@@ -0,0 +1,32 @@
+name: Run Tox Tests
+
+on:
+  push:
+    branches:
+      - master  # Run only on the master branch
+
+jobs:
+  test:
+    name: Test with Tox
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        python-version: [3.7, 3.8, 3.9, 3.10, 3.11, 3.12, 3.13]
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install tox
+        run: |
+          python -m pip install --upgrade pip
+          pip install tox
+
+      - name: Run Tox
+        run: tox -e py${{ matrix.python-version }}

CONTRIBUTING.md

@@ -216,6 +216,15 @@ inv package.build && inv package.install && inv test.cli
 
 Note that this will force install the built wheel from the project `dist/` directory over any existing local install.
 
+### Tox tests
+
+To run tox tests against all supported Python versions:
+
+```bash
+pip install tox
+tox
+```
+
 ## Documentation
 
 The `README.md` file contains a table showing example badges for the different built-in colors. If you modify the

README.md

@@ -13,7 +13,7 @@ Python project for generating badges for your projects
 
 [![buymeacoffee](https://camo.githubusercontent.com/c3f856bacd5b09669157ed4774f80fb9d8622dd45ce8fdf2990d3552db99bd27/68747470733a2f2f7777772e6275796d6561636f666665652e636f6d2f6173736574732f696d672f637573746f6d5f696d616765732f6f72616e67655f696d672e706e67)](https://www.buymeacoffee.com/jongracecox)
 
-Supports: Python 3.7-3.9 (2.7-3.6 support has been dropped)
+Supports: Python 3.7-3.13 (2.7-3.6 support has been dropped)
 
 ## Overview
 

build-requirements.txt

@@ -5,5 +5,6 @@ pytest
 pytest-cov
 requests
 setuptools
+tox
 types-requests
 wheel

tox.ini

@@ -0,0 +1,9 @@
+[tox]
+envlist = py37, py38, py39, py310, py311, py312, py313
+
+[testenv]
+deps =
+    pytest
+    -rbuild-requirements.txt
+commands =
+    pytest --doctest-modules anybadge tests