Unit test coverage is rather poor

[reggert]

The current unit test coverage for the plugin is rather poor. bundleTask is not covered at all, and that's where most of the work is done. bundleTask should be broken up into smaller, testable chunks, with unit tests written for each chunk. Ideally, an end-to-end test for bundleTask should also be written.

[reggert]

I think a good starting point would be to break out everything that modifies the aQute.bnd.osgi.Builder object into a function separate from bundleTask so that we can test that the Builder object is configured properly before bundleTask invokes its build method.