add a discovery event example from a bacnet scan

[gnmerritt]

We'd like to ensure that the discovery events our scanner is emitting our valid UDMI, so we're checking an example into the tests directory. This example is constructed from a live building controller and includes some of its quirks and field naming conventions

[noursaidi]

Hi Nathan,

You can run these tests locally on your machine by using bin/test_schema, and then looking at the .out file which in this example would be tests/event_discovery.tests/from_bacnet.out. If the file is blank then there are no errors

[gnmerritt]

Yep, ran locally before putting the PR up.

Also maybe I'm missing something but it looks to me like the test runner actually compares the .out file with the actual output to make sure they match (rather than writing to it). So that's why e.g. https://github.com/faucetsdn/udmi/blob/master/tests/event_discovery.tests/errors.out is checked in, to make sure that the validator produces those same messages. Is that right?

[grafnu]

Nathan, yes -- that is correct. Some .out files are not empty because they are specifically testing that errors are handled correctly -- but in your case it's good/appropriate that it's empty!

Note that given some of the other changes I'm proposing this will likely need to be adjusted, but that'll come out when I put that PR together.