💡 pytest-inject-config

A pytest plugin that loads a config file given by --config-path and injects it into every test class as self.config. The format is chosen by the file extension: JSON (.json) and YAML (.yaml, .yml). Run the same test suite against different environments by switching a single flag.

📦 Installation

uv add pytest-inject-config

🚀 Features

• ✅ One flag, any environment — point --config-path at a different JSON file per environment
• ✅ Isolated per class — each test class gets its own copy, so a test that mutates its config can't affect others
• ✅ Fails fast — a missing file, an unsupported extension, or invalid content stops the run at startup with a clear usage error
• ✅ JSON and YAML — chosen by extension; only known extensions are accepted, so adding formats later never changes how an existing file is read
• ✅ Safe YAML — YAML is loaded with safe_load, so a config file can never construct Python objects or run code
• ✅ Read once — the file is loaded at startup, not once per class
• ✅ Zero footprint without the flag — nothing is registered and no fixture runs

🛠️ How to Use

1. Create a config file per environment, in JSON:

   {
       "host": "10.0.0.1",
       "port": 8080
   }
   

   or in YAML:

   host: 10.0.0.1
   port: 8080
   

2. Read it from your test classes through self.config:

   class TestDevice:
       def test_connect(self):
           assert connect(self.config["host"], self.config["port"])
   

3. Run with the file for the environment you want:

   pytest --config-path=config/staging.json
   

⚙️ Behavior

▶️ Usage Examples

Select the environment in CI

pytest --config-path="config/${TARGET_ENV}.yaml"

Set a default in pytest.ini

[pytest]
addopts =
    --config-path=config/local.json

🔁 Migrating from pytest-plugins

This plugin was previously add_config_parameters in pytest-plugins, where it never worked. Both register the --config-path option, so don't install them together until you're on a pytest-plugins release without it.

🤝 Contributing

1. Fork the repository
2. Create a feature branch: git checkout -b feature/my-addition
3. Make your changes
4. Commit your changes: git commit -m 'Add my addition'
5. Push to the branch: git push origin feature/my-addition
6. Open a Pull Request

Additions that promote clean, productive, and maintainable development are always welcome.

📄 License

MIT License — see LICENSE for details.

🙏 Thanks

Thanks for exploring this repository!
Happy coding!