Support multiple installed engines

[CharliePoole]

@CharliePoole commented on Sat Dec 12 2015

This may end up being a non-issue, if our existing code takes care of the job, but I have a suspicion it doesn't. Here's what we need to verify and/or implement:

• Multiple engines can be present in well-known locations or pointed to from the registry or settings.
• All such engines should be examined by the EngineActivator when deciding which engine to use.
• Each engine may potentially have it's own set of extensions.
• Each engine may also point to a set of shared extensions.
• In addition to such "findable" engines, any runner may be packaged with a private engine. Such an engine will not be available to other runners.
• The engine that is found and used by a runner should be easily identifiable by the user, in order to facilitate bug reporting and debugging.

While this is not a user-facing feature, being able do the above is a prerequisite for other features we want to implement.

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@CharliePoole commented on Mon Jun 13 2016

Postponing this... it's important but not urgent.

[CharliePoole]

I'm removing my name from this. Hopefully, someone on the @nunit/engine-team will be interested in taking it on. It may not actually be as high a priority as we once thought because (a) we seem to favor having a separate engine for each runner and (b) we have left it for a long time without issues.

[ChrisMaddock]

I'm going to close this issue. We've moved away from the 'centrally installed engine' approach since this was first written, and I don't see it becoming a priority to reinstate in the near furture.