Plan:

Find the unit tests in the repository (their could be multiple "tests/unit" folders).
Ensure each set of unit tests is following the implementation standards.
Run the tests to ensure the code work as expected.

Implementation standards

Testing

Unit test must be implemented with ops.testing:
- See How to migrate unit tests from Harness if the charm is currently using harness.
For each charm in the repository, there should be a tests/ folder like: https://github.com/canonical/platform-engineering-charm-template/tree/main/tests
- Unit tests goes in tests/unit
- Fixtures should look like the ones in https://raw.githubusercontent.com/canonical/haproxy-operator/refs/heads/main/haproxy-operator/tests/unit/conftest.py
- Helper functions should go in tests/unit/helper.py. See an example here: https://raw.githubusercontent.com/canonical/haproxy-operator/refs/heads/main/haproxy-operator/tests/unit/helper.py
- There is a tests/unit/test_charm.py to test the basic behaviors of the charm.
- There should be additional tests/unit/test_xxx.py files to test specific integrations of the charm (see https://github.com/canonical/haproxy-operator/tree/main/haproxy-operator/tests/unit)

The unit tests should be run in a virtual machine named "charmkeeper-unit".

If the machine doesn't exist, create it with: scripts/create-charmkeeper-vm.sh.

If not already done, mount the working directory folder in the machine with

multipass mount --type native $PWD charmkeeper:/workdir

Look at CONTRIBUTING.md to see if there are specific instructions to test the charm.

Unless there is something specific mentioned, you should be able to run the tests with:

multipass exec charmkeeper -d /workdir/ -- tox