Fix tracing module sampling option should default to 1.0 when not set

[oleiade]

What?

This Pull Request ensures that if the sampling option of the tracing module's client is not provided by the user, the Client defaults to sample 100% of the request.

		import http from "k6/http";
		import tracing from "k6/experimental/tracing";

		// We do not set the sampling option, thus the default
		// behavior should be to always sample.
		const instrumentedHTTP = new tracing.Client({
			propagator: "w3c",
		})

Why?

As noted by @Blinkuu, the current behavior of the tracing module client is to use a 0% sampling when the option is not set. It leads to effectively no HTTP request being sampled. Whereas the desired behavior would be to have all requests sampled unless instructed otherwise.

Checklist

• I have performed a self-review of my code.
• I have added tests for my changes.
• I have run linter locally (make ci-like-lint) and all checks pass.
• I have run tests locally (make tests) and all tests pass.
• I have commented on my code, particularly in hard-to-understand areas.

[Blinkuu]

LGTM, thanks!

[oleiade]

It turns out this was caused by a difference in how options are handled between the client and the options. I addressed the issue differently and ensured all the tests passed now.

[codecov-commenter]

Codecov Report

Merging #3231 (4baa0e8) into master (6c31075) will decrease coverage by 0.01%.
Report is 1 commits behind head on master.
The diff coverage is 80.00%.

❗ Current head 4baa0e8 differs from pull request most recent head 9ea8a8f. Consider uploading reports for the commit 9ea8a8f to get more accurate results

@@            Coverage Diff             @@
##           master    #3231      +/-   ##
==========================================
- Coverage   73.24%   73.24%   -0.01%     
==========================================
  Files         259      259              
  Lines       19892    19899       +7     
==========================================
+ Hits        14570    14575       +5     
- Misses       4400     4401       +1     
- Partials      922      923       +1     

Flag	Coverage Δ
ubuntu	73.18% <80.00%> (+<0.01%)	⬆️
windows	73.07% <80.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
js/modules/k6/experimental/tracing/module.go	69.09% <50.00%> (-2.61%)	⬇️
js/modules/k6/experimental/tracing/options.go	88.88% <100.00%> (ø)
log/loki.go	69.08% <100.00%> (+0.60%)	⬆️