[docs] Add coverage API glossary entries

[Evangelink]

Summary

• document the coverage message contract types introduced in Add test coverage messages, coverage threshold checks, and summary #9896
• add entries for coverage metrics, scopes, reports, thresholds, and service interfaces
• cross-link related glossary terms and preserve alphabetical placement

Fixes #10159

[Copilot]

Pull request overview

Documents the MTP coverage API contract introduced in PR #9896.

Changes:

• Adds 13 coverage-related glossary entries.
• Cross-links messages, result models, scopes, metrics, and services.

Show a summary per file

File	Description
docs/glossary.md	Adds coverage API glossary documentation.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 5
• Review effort level: Medium

[Copilot]

Review details

Comments suppressed due to low confidence (2)

docs/glossary.md:470

• ProducerId is not required to equal the collector extension's IDataProducer.Uid; the API only validates that it is a stable, non-empty identifier (the UID is merely a recommended example). Calling it the extension UID conflates this correlation key with ITestCoverageCapabilities.EnabledProducerUids and may mislead producers that intentionally use another stable ID.

A public sealed class in `Microsoft.Testing.Platform.Extensions.Messages` (extends `DataWithSessionUid`) published to the MTP message bus by a coverage collector to report a single coverage measurement. Carries: `Scope` ([CoverageScope](#coveragescope)), `Metric` ([CoverageMetric](#coveragemetric)), `CoveredCount`, `CoverableCount` (both `long`), `ProducerId` (the collector's extension UID), and optionally `CustomMetricName` (when `Metric == CoverageMetric.Custom`). The platform's [ITestCoverageResult](#itestcoverageresult) aggregator consumes these messages using last-write-wins correlation on the full key `(SessionUid, ProducerId, Scope, Metric, CustomMetricName)`. `Percentage` is a convenience computed property. Introduced in [PR #9896](https://github.com/microsoft/testfx/pull/9896). See also [TestCoverageThresholdMessage](#testcoveragethresholdmessage), [TestCoverageReportMessage](#testcoveragereportmessage).

docs/glossary.md:478

• A failed coverage threshold does not unconditionally make the process exit with 14. The exit-code policy applies CoverageThresholdFailed only when the run would otherwise succeed, and --ignore-exit-code 14 can then suppress it; failures such as test failures retain precedence. Documenting the unconditional behavior gives users an incorrect exit-code contract.

A public sealed class in `Microsoft.Testing.Platform.Extensions.Messages` (extends `DataWithSessionUid`) published by a coverage collector to report the result of a coverage threshold evaluation. Carries the same metric identification as [TestCoverageMessage](#testcoveragemessage) plus: `Aggregation` ([CoverageAggregation](#coverageaggregation)), `AggregatedOver` (optional [CoverageScopeLevel](#coveragescopelevel)), `ActualPercentage`, `RequiredPercentage`, `HasCoverableData`, `TreatNoDataAsFailure`, and `Passed` (derived: a threshold with no coverable data passes unless `TreatNoDataAsFailure` is set). When any threshold message has `Passed == false`, `ITestCoverageResult.HasThresholdFailure` returns `true`, causing the process to exit with `ExitCode.CoverageThresholdFailed` (14). Introduced in [PR #9896](https://github.com/microsoft/testfx/pull/9896). See also [TestCoverageMessage](#testcoveragemessage), [ITestCoverageResult](#itestcoverageresult).

• Files reviewed: 1/1 changed files
• Comments generated: 0 new
• Review effort level: Medium

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Note

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Review Summary — PR #10166

This PR adds glossary documentation for the coverage API concepts introduced in PR #9896. It is a documentation-only change (no code, no tests, no public API surface changes).

Verdict Table

#	Dimension	Verdict
1	Algorithmic Correctness	N/A
2	Threading & Concurrency	N/A
3	Public API Design	N/A
4	Backward Compatibility	N/A
5	Cross-TFM Compatibility	N/A
6	Test Coverage & Test Quality	N/A
7	Localization	N/A
8	Performance	N/A
9	Error Handling	N/A
10	Security	N/A
11	IPC/Wire Format	N/A
12	Documentation	✅ Clean
13	Code Style & Conventions	✅ Clean
14	Naming	✅ Clean
15	Resource Management	N/A
16	Nullability	N/A
17	Architecture & Layering	N/A
18	MSBuild / NuGet Packaging	N/A
19	Scope Discipline	✅ Clean
20	TODO / FIXME Policy	✅ Clean
21	Changelog / Release Notes	N/A
22	Copyrights & License Headers	N/A

Overall Verdict

All clear. The glossary entries are well-written, correctly cross-linked, alphabetically ordered, and accurately describe the coverage API surface from PR #9896. No issues found.