Sourceless migration plugins are broken

I converted #20 into an MR and added a unit test.

Removing patches

I typically avoid migration reviews as not my best topic but think I can cover this one.

The solution seems pretty straight forward. Looking at the test coverage https://git.drupalcode.org/issue/drupal-2797421/-/jobs/4553477 and seems to be there, and even better a unit test.

Don't see anything off so will go ahead and mark it.

Thanks

Can we do without the test as per 🌱 [policy, no patch] Better scoping for bug fix test coverage RTBC ? Is this something that needs a test?

Would leave for now and see what committers think.

At least it's a unit test so the overhead is low.

The test seems fine. We had no test coverage around NoSourcePluginDecorator before, so this is a good opportunity to add some.

Does the issue expose a general lack of test coverage for the specific subsystem? If so, is it better to add generic test coverage for that subsystem in a separate issue?

I would say this exposes a lack of test coverage, but since the class essentially exists for the one line we are changing here, it's best to add the coverage here. I would say the majority of the seven questions are no's in the new guidelines, which means the tests are okay to add

Is the fix is easy to verify by manual testing?
no
Is the fix in self-contained/@internal code where we expect minimal interaction with contrib? Examples are plugins, controllers etc.
no
Is the fix achieved without adding new, untested, code paths?
no
Is an explicit 'regression' test needed?
no
Is it easy for someone who did not work on the original bug report to add the test coverage in a followup issue?
yes
Does the issue expose a general lack of test coverage for the specific subsystem? If so, is it better to add generic test coverage for that subsystem in a separate issue?
yes/no
If this fix is committed without test coverage but then later regresses, is the impact likely to be minimal or at least no worse than leaving the bug unfixed?
yes

Committed and pushed c42f5d9328c to 11.x and 8f3ccf4c4b4 to 11.1.x and f26adfd7445 to 10.5.x and a09b4608957 to 10.4.x. Thanks!