[test-improver] Improve tests for tracing package

[github-actions]

File Analyzed

• Test File: internal/tracing/provider_test.go
• Package: internal/tracing
• Lines of Code: 500 → 602

Improvements Made

1. Increased Coverage

• ✅ Added TestInitProvider_InvalidSampleRate — exercises the warning/fallback path in resolveSampleRate when the configured rate is outside [0.0, 1.0] (e.g., -0.5 or 1.5); verifies the default AlwaysSample is used

• ✅ Added TestParentContext_InvalidSpanID — covers the resolveParentContext fallback to a random span ID when spanId fails hex decode or has wrong byte length; uses three sub-cases (non-hex, too-short, too-long)

• ✅ Added TestParentContext_AllZerosTraceID — covers the !sc.IsValid() guard that returns the original context when traceId decodes to all-zero bytes (invalid per W3C Trace Context spec)

• Previous Coverage: 91.7%

• New Coverage: 96.3%

• Improvement: +4.6%

Function	Before	After
resolveSampleRate	60.0%	100.0%
resolveParentContext	81.5%	92.6%
generateRandomSpanID	75.0%	75.0% (error path requires mocking)

2. Better Testing Patterns

• ✅ Table-driven sub-tests for TestInitProvider_InvalidSampleRate and TestParentContext_InvalidSpanID, consistent with existing test style
• ✅ Clear assertions documenting the fallback behavior (e.g., "span should be sampled when rate falls back to default 1.0")
• ✅ W3C traceparent round-trip check in TestParentContext_InvalidSpanID to confirm the enriched context carries the correct traceId

Test Execution

All tests in the tracing package pass:

ok  github.com/github/gh-aw-mcpg/internal/tracing  0.013s  coverage: 96.3%

Note: TestFetchAndFixSchema_NetworkError in internal/config fails on the baseline (pre-existing, unrelated to this PR).

Why These Changes?

The tracing package had three functions with meaningful untested branches. resolveSampleRate at 60% left the warning/default path completely uncovered, meaning misconfigured sample rates (outside [0.0, 1.0]) were not validated by tests. resolveParentContext at 81.5% missed the span ID fallback logic that silently generates a random span ID — an important spec behaviour (T-OTEL-008). The all-zeros TraceID path guarded by !sc.IsValid() was also untested. All three gaps are now covered with clear, focused test cases.

---

Generated by Test Improver Workflow
Focuses on better patterns, increased coverage, and more stable tests

Warning

⚠️ Firewall blocked 1 domain

The following domain was blocked by the firewall during workflow execution:

• invalidhostthatdoesnotexist12345.com

To allow these domains, add them to the network.allowed list in your workflow frontmatter:

network:
  allowed:
    - defaults
    - "invalidhostthatdoesnotexist12345.com"

See Network Configuration for more information.

Generated by Test Improver · ● 3.3M · ◷

[Copilot]

Pull request overview

Improves unit test coverage for the internal/tracing provider initialization and W3C parent context resolution paths, focusing on previously untested invalid configuration inputs.

Changes:

• Add table-driven coverage for invalid tracing SampleRate values to exercise the fallback-to-default path.
• Add coverage for invalid spanId inputs to confirm ParentContext falls back to generating a random span ID while preserving the configured traceId.
• Add coverage for the all-zero traceId validity guard to ensure ParentContext returns the original context unchanged.

Show a summary per file

File	Description
internal/tracing/provider_test.go	Adds new test cases for invalid sample rates and additional ParentContext fallback/guard branches.

Copilot's findings

Tip

Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

• Files reviewed: 1/1 changed files
• Comments generated: 1

[Copilot]

The doc comment says the random span ID path is only when spanId is "not valid hex", but this test also covers valid-hex values with invalid byte length (too short/too long). Update the comment to reflect both decode errors and wrong-length inputs so the test intent stays accurate.

Suggested change

	// generating a random span ID when the configured spanId is not valid hex, and still
	// returns an enriched context (per spec T-OTEL-008).
	// generating a random span ID when the configured spanId is not valid hex or is valid
	// hex with the wrong byte length, and still returns an enriched context (per spec
	// T-OTEL-008).