ops-harness 0.1

Testing the Python library behind great charms

ops-harness

ops-harness provides Harness, the legacy unit-testing API for charms built with the ops framework. It packages the Harness class as a standalone distribution that ops re-exports as ops.testing.Harness -- the same way ops re-exports the ops-scenario package's state-transition API under ops.testing.

[!IMPORTANT] Harness is deprecated. For new charms, and where reasonable for existing charms, prefer the state-transition testing API in ops.testing (the ops-scenario package). ops-harness exists so that charms that still rely on Harness can continue to do so as the class is removed from the core ops distribution.

• ops-harness requires Python 3.8 or above.
• It depends on ops 2.23 or above.

Installation

pip install ops-harness

Or, with uv:

uv add ops-harness

Usage

Add ops-harness to your charm's test dependencies, then import Harness from ops.testing:

from ops.testing import Harness

from charm import MyCharm


def test_config_changed():
    harness = Harness(MyCharm, meta="name: my-charm")
    harness.begin()
    harness.update_config({"log-level": "debug"})
    assert harness.charm.model.config["log-level"] == "debug"
    harness.cleanup()

For the full API, see the ops.testing.Harness reference documentation.

Contributing and developing

Anyone can contribute to ops-harness. See CONTRIBUTING.md for the contribution process, and HACKING.md for how to set up a development environment and run the tests.

Code of conduct

When contributing, you must abide by the Ubuntu Code of Conduct.

License

ops-harness is free software, distributed under the Apache Software License, version 2.0. See LICENSE for details.