missing coverage of charm events

https://git.launchpad.net/charm-k8s-jenkins-agent/tree/tests/unit/test_charm.py

has no test coverage for what happens if a user changes config.

You could do that testing with the operator framework's testing harness along the lines of:

from ops import testing

harness = testing.Harness(JenkinsAgentCharm)
harness.begin()
harness.update_config({'config_key': 'new_value'})

and then introspect attributes of 'harness.charm' to see if config changed was properly handled.

Note there is an open Operator issue for cleaner testing support of pod-spec-set:
https://github.com/canonical/operator/issues/261

If there is something that you would like to see that would make testing of charm behavior clear and clean for you, please leave comments on that issue.