DefaultLauncher should catch exceptions thrown by test engines

[jlink]

Overview

If a test engine throws an exception during discovery (see https://github.com/junit-team/junit5/blob/master/junit-platform-launcher/src/main/java/org/junit/platform/launcher/core/DefaultLauncher.java#L115) other engines won't be queried any more.

I think this is a bug because one test engine can thereby prevent others from working.

Deliverables

• DefaultLauncher should catch and report exceptions from engines and proceed with other engines.
  • This applies to both the discovery phase and execution phase.

Additional Proposals

• DefaultLauncher could even collect discovery results concurrently.

[sbrannen]

Thanks for raising the issue.

I totally agree!

The same applies to the execution phase as well.

[sbrannen]

DefaultLauncher could even collect discovery results concurrently.

It could do that, but I consider that a separate topic. I have therefore updated this issue's description to reflect the deliverables.

Feel free to create a new issue to propose concurrent test discovery across registered engines.

[sbrannen]

Slated for M5 since we are trying to get M4 out the door as soon as possible.