Use tracer and meter test helpers from the OTEL repository instead of the internal ones

[matej-g]

For some time, the test helpers have existed in parallel in both otel and contrib repositories. Although helpers were functionally very similar in both repositories, not all helpers have been exported from the main otel repository, which resulted in some duplication of helper methods.

This is no longer the case, as helpers for both tracer and meter are now "stabilized" and exported in the main otel repository (go.opentelemetry.io/otel/api/trace/tracetest and go.opentelemetry.io/otel/api/metric/metrictest as of current version 0.13.0). This makes it possible to replace internal helpers in contrib by the ones exported from otel repo and subsequently to remove internal helpers, resolving in cleaner and slimmer codebase.

Changes include:

• Replacing internal helpers by external ones in instrumentation modules + related test changes
• Replacing internal helpers by external ones in propagators modules + related test changes
• Removal of internal helper packages
• go mod related changes in affected modules

Resolves #385 and effectively resolves #31, #43 as well

[matej-g]

FYI, looks like from next version, the test helper packages in otel repo have been moved by open-telemetry/opentelemetry-go#1229 and open-telemetry/opentelemetry-go#1252, so the import paths should be changed to go.opentelemetry.io/otel/oteltest before the next release.

[MrAlias]

Looks solid 👍

Thanks for digging into this!

[XSAM]

👍

[Aneurysm9]

I'm overall in favor of this, but the Event addition in #413 makes me think perhaps we should ensure that we have fully-working helper implementations before relying on the main repo. Otherwise we may find ourselves in a situation where multiple releases need to happen in order to properly test an addition in this repo.

[matej-g]

I'm overall in favor of this, but the Event addition in #413 makes me think perhaps we should ensure that we have fully-working helper implementations before relying on the main repo. Otherwise we may find ourselves in a situation where multiple releases need to happen in order to properly test an addition in this repo.

I guess Events are in the oteltest package already (https://github.com/MrAlias/opentelemetry-go/commits/master/oteltest/event.go). Are we missing something else in the main repo?

[MrAlias]

@Aneurysm9 are you good with merging this and possibly opening an issue to address the concerns you raised?

[Aneurysm9]

Yup, I'm good. It looks like the main repo has more in the oteltest package than the subset here, so we should be good to use that package.