Return noop TracerProvider when no trace processors are defined

[hxiao87]

Description

Returns noop TracerProvider when no processors are defined such that this scenarios is treats the same as when LevelNone is set.

Link to tracking issue

Fixes #15135

Testing

• Updated existing tests in trace_test.go to make sure there's no behavior change
• Added TestCreateTracerProvider_NoProcessors to verify that the default config (level=Basic,
  no processors) returns a noop provider

Documentation

Didn't find any relevant doc that needs update.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.23%. Comparing base (5a2da78) to head (97f9c64).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #15186   +/-   ##
=======================================
  Coverage   91.23%   91.23%           
=======================================
  Files         701      701           
  Lines       45838    45838           
=======================================
  Hits        41822    41822           
  Misses       2816     2816           
  Partials     1200     1200           

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[axw]

@hxiao87 thanks for the PR. Tests are failing - please fix those and mark this ready for review when you have everything passing.

[hxiao87]

@hxiao87 thanks for the PR. Tests are failing - please fix those and mark this ready for review when you have everything passing.

Hi Andrew, thanks for reviewing! I have run the tests locally and confirmed they'd pass. Looks like an approval is needed to kick off the CI, so I'll just open the PR again. While addressing the CI failures from the MissingResource test, I figuredcreateTracerProvider (and similarly createMeterProvider) would also panic if called with MigratedFromV02 = true and a similar test setup. I guess in practice this shouldn't happen since the factory always provides a Logger, but let me know if you feel like a guard could be beneficial and I can make a follow-up change.

[axw]

I figured createTracerProvider (and similarly createMeterProvider) would also panic if called with MigratedFromV02 = true and a similar test setup. I guess in practice this shouldn't happen since the factory always provides a Logger, but let me know if you feel like a guard could be beneficial and I can make a follow-up change.

Yeah that won't happen in practice, a logger will always be provided in a real collector. We could make the test more realistic by passing in a logger (probably a no-op logger), but your change is fine for now.

[codspeed-hq]

Merging this PR will not alter performance

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

✅ 7 untouched benchmarks
⏩ 76 skipped benchmarks¹

---

_{Comparing hxiao87:noop-trace (97f9c64) with main (5a2da78)}

Footnotes

1. 76 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[axw]

The spell-check failure doesn't appear to be related to this branch. Should be good to merge

[florianl]

Is there a reason to move this if-clause after createFixedResourceConfig()? cfg.Traces.Level and cfg.Traces.Processors shouldn't be changed by createFixedResourceConfig() - are they?

[hxiao87]

No, createFixedResourceConfig doesn't modify those fields. With the existing order, this test panics as it passes an empty TracerSettings{} (w/ nil Logger) with no processors - thus moving the resource validation to the front.

[otelbot]

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