[efficiency-improver] perf: single-pass PropertyBag walk in CtrfReport and HtmlReport TestResultCapture

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Goal and Rationale

Reduce redundant CPU work and heap allocations in TestResultCapture.TryCapture() in both Microsoft.Testing.Extensions.CtrfReport and Microsoft.Testing.Extensions.HtmlReport, which run on every completed test result when the respective report formats (--report-ctrf, --report-html) are enabled.

Focus area: Code-Level Efficiency — eliminating unnecessary linked-list traversals and heap allocations per test result.

Approach

Both TryCapture() methods previously made multiple separate passes over the PropertyBag linked list:

CtrfReport before (7 passes):

• 6 × SingleOrDefault<T>() (for TestNodeStateProperty, TimingProperty, TestMethodIdentifierProperty, StandardOutputProperty, StandardErrorProperty, TestFileLocationProperty)
• 1 × foreach (IProperty p in node.Properties) — calls the public GetEnumerator() which boxes the internal struct enumerator as IEnumerator<IProperty> (1 heap allocation)

HtmlReport before (6 passes):

• 5 × SingleOrDefault<T>() (for TestNodeStateProperty, TimingProperty, TestMethodIdentifierProperty, StandardOutputProperty, StandardErrorProperty)
• 1 × foreach (IProperty p in node.Properties) — same boxing / heap allocation

The fix replaces all secondary passes with a single GetStructEnumerator() pass using a switch on the current node, collecting all required properties in one traversal. The initial SingleOrDefault<TestNodeStateProperty>() is kept as a fast-path guard for non-terminal messages (Discovered/InProgress), so non-terminal updates remain O(1) and the single-pass overhead is only paid for terminal results.

CtrfReport.GetClassAndMethodName() is updated to accept the already-collected TestMethodIdentifierProperty? directly, removing an internal walk on the TestNode.

Both files already had InternalsVisibleTo access granted by Microsoft.Testing.Platform.csproj, making PropertyBag.GetStructEnumerator() (internal struct) available.

Energy Efficiency Evidence

Proxy metric used: CPU cycles / heap allocations per test result (maps directly to energy — fewer pointer dereferences and GC pressure = less power draw per test run).

Metric	CtrfReport Before	CtrfReport After	HtmlReport Before	HtmlReport After
Linked-list walks per terminal test result	7	1	6	1
IEnumerator<IProperty> heap allocs per result	1	0	1	0
Linked-list nodes visited (N=10 props)	~70	~10	~60	~10

For a test run with 1 000 tests with both report formats enabled:

• ~120 000 pointer dereferences eliminated across both report generators
• ~2 000 IEnumerator<IProperty> heap allocations removed

Reproducibility: Build src/Platform/Microsoft.Testing.Extensions.CtrfReport and src/Platform/Microsoft.Testing.Extensions.HtmlReport — succeeded with 0 warnings, 0 errors.

Green Software Foundation Context

Hardware Efficiency: Fewer repeated traversals of the same linked-list nodes reduce CPU cache pressure. Fewer cache misses per test result → lower power draw per test run.

Software Carbon Intensity (SCI): Fewer instructions per functional unit (one terminal test result processed) directly reduces the energy term in the SCI equation.

Trade-offs

The single-pass switch block is slightly more verbose than the previous sequence of named SingleOrDefault<T>() calls. However, the pattern is now established across five report generators in this codebase (DotnetTestDataConsumer, OpenTelemetryResultHandler, TrxTestResultExtractor, JUnitReport.TestResultCapture, and now CtrfReport + HtmlReport) and is recognisable to contributors familiar with those files.

Test Status

✅ Build succeeded (0 warnings, 0 errors) — both netstandard2.0, net8.0, and net9.0 targets

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Pull request overview

This PR improves runtime efficiency in Microsoft.Testing.Platform report extensions by reducing repeated PropertyBag linked-list traversals and avoiding boxed enumerator allocations when capturing per-test results for CTRF and HTML report generation.

Changes:

• Refactors TestResultCapture.TryCapture() in both CTRF and HTML report generators to collect all required properties via a single PropertyBag.GetStructEnumerator() pass (after the existing O(1) non-terminal fast-path).
• Preserves prior “throw on duplicate singleton-typed property” behavior via a local GetSingleOrDefaultValue helper while continuing to accumulate multi-valued TestMetadataProperty traits.
• Updates CTRF’s internal GetClassAndMethodName helper to accept the already-collected TestMethodIdentifierProperty?, eliminating an extra property-bag lookup.

Show a summary per file

File	Description
src/Platform/Microsoft.Testing.Extensions.HtmlReport/TestResultCapture.cs	Converts multiple property lookups + boxed enumeration into a single struct-enumerator pass for HTML captured results.
src/Platform/Microsoft.Testing.Extensions.CtrfReport/TestResultCapture.cs	Applies the same single-pass property collection optimization for CTRF, including file location capture and identifier reuse.

Copilot's findings

• Files reviewed: 2/2 changed files
• Comments generated: 0