Fix broken main: declare new BaseSerializer helper members in InternalAPI

[Evangelink]

Problem

main is broken. The official build 3018307 failed with RS0051 on all target frameworks of Microsoft.Testing.Platform (netstandard2.0, net8.0, net9.0):

src\Platform\Microsoft.Testing.Platform\IPC\Serializers\BaseSerializer.cs(359,27): error RS0051:
  Symbol 'static ...BaseSerializer.ReadFields(...) -> void' is not part of the declared API
src\Platform\Microsoft.Testing.Platform\IPC\Serializers\BaseSerializer.cs(380,27): error RS0051:
  Symbol 'static ...BaseSerializer.WriteListPayload<T>(...) -> void' is not part of the declared API

The downstream "Publish Test Results / binlogs" and "OneLocBuild (testsuite not found)" failures are just consequences — the failed build produced no packages/artifacts for those later steps to consume.

Root cause

Two recent changes landed close together:

• Deduplicate DotnetTest IPC serializer 3-phase boilerplate #9774 ("Deduplicate DotnetTest IPC serializer 3-phase boilerplate") added the protected static helpers ReadFields and WriteListPayload<T> to BaseSerializer.
• Add InternalAPI tracking to all projects with PublicAPI #9752 ("Add InternalAPI tracking to all projects with PublicAPI") turned on the internal/public API analyzer for these projects.

The new members were never added to InternalAPI.Unshipped.txt, so the analyzer rejected them.

Fix

BaseSerializer.cs is compiled as shared source (<Compile Include=... Link=... />) into several projects that each have InternalAPI (RS0051) tracking. The two new members are declared in every one of them:

• Microsoft.Testing.Platform (both the netstandard2.0 root and net/ variants)
• Microsoft.Testing.Extensions.HangDump
• Microsoft.Testing.Extensions.Retry
• Microsoft.Testing.Extensions.TrxReport
• Microsoft.Testing.Extensions.MSBuild

(Microsoft.Testing.Platform.MSBuild also compiles the file but has no InternalAPI tracking, so it needs no entry.)

Verification

Release builds of Microsoft.Testing.Platform and all four tracked extensions succeed with 0 warnings, 0 errors across net8.0, net9.0, and netstandard2.0.

Co-authored-by: Copilot App 223556219+Copilot@users.noreply.github.com

[Copilot]

Pull request overview

This PR aims to unbreak main, whose official build was failing with RS0051 in Microsoft.Testing.Platform after two PRs landed close together: #9774 added the protected static helpers ReadFields/WriteListPayload<T> to BaseSerializer, and #9752 turned on internal-API (RS0051) tracking for the project. The two new members were never declared in the InternalAPI tracking files, so the analyzer rejected them. The fix adds the two member signatures to the platform's InternalAPI.Unshipped.txt (both the netstandard2.0 root variant and the net/ variant).

Changes:

• Declares BaseSerializer.ReadFields(...) and BaseSerializer.WriteListPayload<T>(...) in the platform's root InternalAPI.Unshipped.txt.
• Declares the same two members in the net/ variant of the platform's InternalAPI.Unshipped.txt.

The signatures are accurate, but the fix is incomplete: BaseSerializer.cs is also compiled as shared source into four other InternalAPI-tracked projects (Extensions.HangDump, Extensions.Retry, Extensions.TrxReport, Extensions.MSBuild). Their InternalAPI.Shipped.txt baselines already track BaseSerializer's other members but not these two, so they will each hit the same RS0051 failure once the platform build (their ProjectReference dependency) succeeds. The single-project local verification did not exercise those projects, so the gap went unnoticed. As a result, main would remain broken.

Show a summary per file

File	Description
src/Platform/Microsoft.Testing.Platform/InternalAPI/InternalAPI.Unshipped.txt	Declares the two new BaseSerializer helpers for the netstandard2.0 variant; correct but insufficient alone.
src/Platform/Microsoft.Testing.Platform/InternalAPI/net/InternalAPI.Unshipped.txt	Declares the same two helpers for the net8.0/net9.0 variant; correct but insufficient alone.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 1
• Review effort level: Medium

[github-actions]

Note

🤖 Automated review by GitHub Copilot. Generated by the Expert Code Review workflow. To request a follow-up action, reply by tagging @copilot directly.

Review Summary

✅ All 22 dimensions clean — no issues found.

This is a minimal, correctly-scoped fix for the broken main build (RS0051). Verified:

Check	Result
Signatures match source (BaseSerializer.cs:359, :380)	✅
Both TFM variants updated (root + net/)	✅
Entries alphabetically sorted (R before W)	✅
Trailing newline present (SA1518)	✅
No other undeclared BaseSerializer members remain	✅ (27 others already in Shipped.txt)
Scope discipline — single concern, no unrelated changes	✅

No inline comments needed — the change is correct as-is.

[github-actions]

🔍 Build Failure Analysis

Summary — Build failed with 24 RS0051 errors because two new protected static methods on BaseSerializer were declared in the Platform project's InternalAPI.Unshipped.txt but not in the extension projects that compile the same source file directly.

Root cause: Missing InternalAPI.Unshipped.txt entries in extension projects

BaseSerializer.cs is compiled into multiple extension projects as linked source (via <Compile Include="$(RepoRoot)src\Platform\Microsoft.Testing.Platform\IPC\Serializers\BaseSerializer.cs" Link="..." />). Because the Roslyn Public API Analyzer (RS0051) runs per-compilation, each project that compiles this file requires its own API declaration.

The PR correctly updated:

• ✅ src/Platform/Microsoft.Testing.Platform/InternalAPI/InternalAPI.Unshipped.txt
• ✅ src/Platform/Microsoft.Testing.Platform/InternalAPI/net/InternalAPI.Unshipped.txt

But missed these 4 files (which currently contain only #nullable enable):

• ❌ src/Platform/Microsoft.Testing.Extensions.HangDump/InternalAPI/InternalAPI.Unshipped.txt
• ❌ src/Platform/Microsoft.Testing.Extensions.MSBuild/InternalAPI.Unshipped.txt
• ❌ src/Platform/Microsoft.Testing.Extensions.Retry/InternalAPI/InternalAPI.Unshipped.txt
• ❌ src/Platform/Microsoft.Testing.Extensions.TrxReport/InternalAPI/InternalAPI.Unshipped.txt

Affected projects (all failed for the same reason)

Project	Error count
Microsoft.Testing.Extensions.HangDump	6
Microsoft.Testing.Extensions.MSBuild	6
Microsoft.Testing.Extensions.Retry	6
Microsoft.Testing.Extensions.TrxReport	6

Proposed fix — Add the same two API declarations to each of the 4 extension project InternalAPI.Unshipped.txt files. Each file should become:

#nullable enable
static Microsoft.Testing.Platform.IPC.Serializers.BaseSerializer.ReadFields(System.IO.Stream! stream, System.Func<ushort, int, bool>! tryReadField) -> void
static Microsoft.Testing.Platform.IPC.Serializers.BaseSerializer.WriteListPayload<T>(System.IO.Stream! stream, ushort fieldId, T[]? list, System.Action<System.IO.Stream!, T>! writeItem) -> void

Note: Microsoft.Testing.Platform.MSBuild also includes BaseSerializer.cs as linked source but does not have the Public API Analyzer enabled, so it is unaffected.

---

Build overview

• Result: FAILED
• Duration: 211.2s
• MSBuild: 18.8.0-preview-26302-115
• Projects: 49 total, 6 failed
• Errors: 25 (24 RS0051 + 1 final "Build failed")
• Warnings: 0
• Failed target: CoreCompile (via Csc task)

All MSBuild errors (24 unique)

Code	Project	File:Line	Message
RS0051	HangDump	BaseSerializer.cs:359	Symbol ReadFields(...) is not part of the declared API
RS0051	HangDump	BaseSerializer.cs:380	Symbol WriteListPayload<T>(...) is not part of the declared API
RS0051	MSBuild	BaseSerializer.cs:359	Symbol ReadFields(...) is not part of the declared API
RS0051	MSBuild	BaseSerializer.cs:380	Symbol WriteListPayload<T>(...) is not part of the declared API
RS0051	Retry	BaseSerializer.cs:359	Symbol ReadFields(...) is not part of the declared API
RS0051	Retry	BaseSerializer.cs:380	Symbol WriteListPayload<T>(...) is not part of the declared API
RS0051	TrxReport	BaseSerializer.cs:359	Symbol ReadFields(...) is not part of the declared API
RS0051	TrxReport	BaseSerializer.cs:380	Symbol WriteListPayload<T>(...) is not part of the declared API

(Each error repeats 3× per project due to multi-targeting — 3 TFMs × 4 projects × 2 symbols = 24 errors.)

---

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[github-actions]

🤖 Automated content by GitHub Copilot. Generated by the Build Failure Analysis workflow. · 105.3 AIC · ⌖ 7.25 AIC · ⊞ 7.3K · ◷

[Copilot]

Review details

• Files reviewed: 6/6 changed files
• Comments generated: 0 new
• Review effort level: Medium

[Copilot]

Review details

• Files reviewed: 7/7 changed files
• Comments generated: 0 new
• Review effort level: Low