Forward Azure DevOps log commands and host display messages to dotnet test (protocol 1.2.0/1.3.0)

[Evangelink]

Summary

Implements the consumer (SDK) side of the dotnet test (Microsoft.Testing.Platform pipe protocol) feature that lets Azure DevOps log grouping — and other forwarded host messages — reach the pipeline log. The host half already shipped in microsoft/testfx; this is the previously-missing dotnet/sdk half.

Under dotnet test with MTP, the test host runs as a child process and talks to the SDK over a named pipe. The host installs a forwarding output device that forwards two message classes over the pipe, gated on the negotiated protocol version:

• AzureDevOpsLogMessage (serializer id 11, protocol 1.2.0+) — verbatim Azure DevOps logging commands (##[group] / ##[endgroup] / ##vso[...]) produced by the AzureDevOpsReport extension. Must be written verbatim so AzDO renders the collapsible group.
• DisplayMessage (serializer id 12, protocol 1.3.0+) — generic host warning/error/info diagnostics produced outside test results (hang/crash dump, retry summaries, generic extension/framework warnings+errors).

The SDK previously advertised only 1.0.0;1.1.0, so the host silently swallowed all of it. That was the core blocker.

Changes

• CliConstants.cs: ProtocolConstants.SupportedVersions bumped 1.0.0;1.1.0 → 1.0.0;1.1.0;1.2.0;1.3.0. Added DisplayMessageLevels (Information=0, Warning=1, Error=2). 1.4.0 (reverse server-control pipe / server-initiated cancellation) is intentionally not advertised — separate, larger feature, out of scope (noted in a comment).
• ObjectFieldIds.cs (vendored from testfx): added the id-11 (AzureDevOpsLogMessageFieldsId) and id-12 (DisplayMessageFieldsId) field classes. Ids 13/14 (server control, 1.4.0) intentionally omitted. The vendored baseline blob SHA in eng/vendored-files.json already matches upstream HEAD, so no manifest bump is needed.
• Models (IPC/Models/): AzureDevOpsLogMessage(ExecutionId, InstanceId, LogText) and DisplayMessage(ExecutionId, InstanceId, byte Level, Text).
• Serializers (IPC/Serializers/): AzureDevOpsLogMessageSerializer and DisplayMessageSerializer, mirroring the SDK's BaseSerializer + INamedPipeSerializer style. Wire layout matches testfx byte-for-byte (Level always written as a single byte; deserialize honors fieldSize so a future widening won't misalign). Both registered in RegisterSerializers.cs.
• Dispatch (TestApplication.cs): route id 11 → OnAzureDevOpsLogReceived, id 12 → OnDisplayMessageReceived.
• TestApplicationHandler.cs: verbatim write of LogText for AzDO; Level-mapped write for display messages (0→message, 1→warning, 2→error). Lenient — these are informational, not tied to a session, so they don't require the TestHost handshake and don't fail the run on missing content. Added matching trace-logging helpers.
• TerminalTestReporter.cs: added WriteWarningMessage (DarkYellow) and WriteErrorMessage (DarkRed) sinks — the reporter previously only had a plain WriteMessage, so there was no clean warning/error sink for the display-message path.
• Tests: serializer round-trip tests for both new serializers (populated fields, null-field omission, always-present Level byte, serializer-id contract).

Verification

• Production CLI (src/Cli/dotnet/dotnet.csproj) builds clean: 0 warnings, 0 errors.
• New serializer round-trip tests pass (--filter FullyQualifiedName~SerializerTests): 15/15 passed, 0 failed, covering ExecutionId/InstanceId/LogText and ExecutionId/InstanceId/Level/Text preservation including null-field omission and the always-present Level byte.

Notes

• ObjectFieldIds.cs is vendored from testfx (src/Platform/Microsoft.Testing.Platform/ServerMode/DotnetTest/IPC/ObjectFieldIds.cs) and tracked in eng/vendored-files.json.
• Left as draft per request.

[Copilot]

Pull request overview

This PR updates the .NET SDK-side dotnet test Microsoft.Testing.Platform (MTP) named-pipe protocol support to negotiate newer protocol versions and forward new host-originated message types (Azure DevOps log commands and generic display diagnostics) to the CLI output, enabling Azure DevOps log grouping and better host diagnostics visibility.

Changes:

• Advertise MTP protocol versions 1.2.0 and 1.3.0 (while explicitly not advertising 1.4.0).
• Add IPC models + serializers for AzureDevOpsLogMessage (id 11) and DisplayMessage (id 12), register them, and dispatch them through TestApplication → TestApplicationHandler.
• Extend terminal reporting to support warning/error display message sinks and add serializer round-trip tests for the new message types.

Show a summary per file

File	Description
test/dotnet.Tests/CommandTests/Test/DisplayMessageSerializerTests.cs	Adds round-trip and serializer-id contract tests for DisplayMessageSerializer.
test/dotnet.Tests/CommandTests/Test/AzureDevOpsLogMessageSerializerTests.cs	Adds round-trip and serializer-id contract tests for AzureDevOpsLogMessageSerializer.
src/Cli/dotnet/Commands/Test/MTP/TestApplicationHandler.cs	Handles forwarding of Azure DevOps log commands and generic display messages to terminal output.
src/Cli/dotnet/Commands/Test/MTP/TestApplication.cs	Dispatches newly supported IPC request types to the handler.
src/Cli/dotnet/Commands/Test/MTP/Terminal/TerminalTestReporter.cs	Adds warning/error output helpers for terminal reporting.
src/Cli/dotnet/Commands/Test/MTP/IPC/Serializers/RegisterSerializers.cs	Registers the new serializers (ids 11 and 12).
src/Cli/dotnet/Commands/Test/MTP/IPC/Serializers/DisplayMessageSerializer.cs	Implements wire-format serializer/deserializer for DisplayMessage.
src/Cli/dotnet/Commands/Test/MTP/IPC/Serializers/AzureDevOpsLogMessageSerializer.cs	Implements wire-format serializer/deserializer for AzureDevOpsLogMessage.
src/Cli/dotnet/Commands/Test/MTP/IPC/ObjectFieldIds.cs	Vendors field/serializer IDs for the new message types and documents omitted upstream ids.
src/Cli/dotnet/Commands/Test/MTP/IPC/Models/DisplayMessage.cs	Adds IPC model for DisplayMessage.
src/Cli/dotnet/Commands/Test/MTP/IPC/Models/AzureDevOpsLogMessage.cs	Adds IPC model for AzureDevOpsLogMessage.
src/Cli/dotnet/Commands/Test/CliConstants.cs	Adds DisplayMessageLevels and expands supported protocol versions.

Copilot's findings

• Files reviewed: 12/12 changed files
• Comments generated: 2