Include original exception in new exception in on_communication_failure

[dentarg]

At https://github.com/twingly/ecco/blob/v0.5.0/lib/ecco/lifecycle_failure_listener.rb#L9-L12 we get an exception from Java, and create a new Ruby exception which we return to the user with the message from the old exception.

Often the message is nil, so it would be useful to also include the original exception, to help the user understand what's going on.

Like Ruby does since 2.1 with Exception Causes.

[roback]

Not sure how we should solve this. There is no Exception#cause= method. We could implement our own on the error classes, but would be nice if there was a way to avoid that :)

Some related comments: https://bugs.ruby-lang.org/issues/8257#note-32

[walro]

Ah yes, we could tweak the error message instead possibly. Like:

message = "#{exception.get_name}: #{exception.get_message)"
error = Ecco::Error::CommunicationError.new(message)

I think Sequel does something like this when wrapping, say, PostgreSQL errors.

[dentarg]

We could implement our own on the error classes

I was thinking that.

[walro]

RE Sequel: https://github.com/jeremyevans/sequel/blob/2241ce3835fb20a3c9d5502ba958bff7d423da39/lib/sequel/core.rb#L130-L132

They do both :) (Message and wrap).

[walro]

A downside with wrap could be that we, possibly, don't want to pass on Java objects to the end users. Kind of what we want to avoid with #26

[dentarg]

True, maybe we should just extract all info there is to our own Ruby exception

The API doesn't look that big: https://docs.oracle.com/javase/7/docs/api/java/lang/Throwable.html

[dentarg]

Interesting issue about Java and Ruby exceptions: jruby/jruby#4781

[walro]

we could do two passes:

1. just include the class name (as suggested in Include original exception in new exception in on_communication_failure #13 (comment)) (this would close this issue)
2. error super object with stuff like orignal stacktrace and what not (new issue)