RealJenkinsRule.addSyntheticPlugin

[jglick]

Fixes #623. Unfortunately I have hit a roadblock: even when RoundEnvironment.processingOver, *.class files for sources have not yet been written to disk, so it is impossible to pack them into the plugin archive.

[Vlatombe]

Looks good, why is it still in draft?

[jglick]

why is it still in draft?

Because I never actually had a use case for it—the proprietary change for which I had planned to use it turned out to be testable by just injecting an extension loaded from the test class loader. (In that case Descriptor was not needed, nor did the test extension need to be deserialized, etc.) Do you have a use case for this? If so, I am happy to take it out of draft.

[jglick]

I now have a definite use case for this utility in a proprietary plugin: a case where I need for the test to run a mock @Extension which must be active before Jenkins completes initialization (and thus before I can runRemotely something to install it).