Yeah, I think that’s good advice for client apps. I didn’t know Span defined a behavior and hadn’t thought about mocking the set_attributes method, so that’s good to know!
I’m actually working on a library that defines and links spans so it’s nice to have a bit more control. A couple folks on slack pointed me toward the pid and ets exporters. The example they linked registers the pid exporter to send spans to the test process and then assert that the received span has the correct attributes.
Honestly, I haven’t worked with OpenTelemetry, and don’t know if OpenTelemetry.Span defines behaviour (seems like it’s not)
But for mocking with Mox if behaviour is not defined by lib I would write it and have the lib’s original module as one of the implementations.
Thank you for following up in here with those ideas!