Fix InvalidOperationException in BuildServerTestHostAsync when telemetry is enabled

[Evangelink]

Regression

PR #8211 registered ServerTelemetry in the service provider before calling LogTestHostCreatedAsync inside BuildServerTestHostAsync. Because ServerTestHost's JSON-RPC message handler (_messageHandler) is only initialized inside InternalRunAsync, the build-time TestHostBuilt telemetry event attempted to flow through the not-yet-initialized server, causing ServerTestHost.AssertInitialized to throw InvalidOperationException during TestApplicationBuilder.BuildAsync().

Reported during dogfood of MTP in the Coverage repo:

   at Microsoft.Testing.Platform.Hosts.ServerTestHost.AssertInitialized()
   at Microsoft.Testing.Platform.Hosts.ServerTestHost.SendMessageAsync(...)
   at Microsoft.Testing.Platform.Hosts.ServerTestHost.SendTelemetryEventUpdateAsync(...)
   at Microsoft.Testing.Platform.Telemetry.ServerTelemetry.PushTelemetryToServerTestHostAsync(...)
   at Microsoft.Testing.Platform.Telemetry.ServerTelemetry.LogEventAsync(...)
   at Microsoft.Testing.Platform.Hosts.TestHostBuilder.LogTestHostCreatedAsync(...)
   at Microsoft.Testing.Platform.Hosts.TestHostBuilder.BuildServerTestHostAsync(...)

The bug does not reproduce in CI because Arcade sets DOTNET_CLI_TELEMETRY_OPTOUT=1 on the test process, which causes LogTestHostCreatedAsync to early-return before reaching ServerTelemetry.

Fix

Move the ReplaceService<ITelemetryCollector>(ServerTelemetry) call below LogTestHostCreatedAsync. The build-time TestHostBuilt event now goes through the originally-registered collector (typically NopTelemetryService), restoring the pre-#8211 behavior for that single event. Runtime telemetry events still flow through ServerTelemetry once the server is fully built and running.

Regression test

Added ServerLoggingTests.RunningInServerJsonRpcModeWithTelemetryEnabled_DoesNotCrashDuringBuildAsync which explicitly opts into telemetry (sets DOTNET_CLI_TELEMETRY_OPTOUT=0 and TESTINGPLATFORM_TELEMETRY_OPTOUT=0 to override any inherited opt-out) and verifies the server boots and responds to Initialize. Without the fix, this test fails with the exact stack trace above; with the fix, it passes.

Also extended ServerModeTestsBase.StartAsServerAndConnectToTheClientAsync with an overload accepting additional environment variables.

Validation

• Reproduced the original crash with the new test against baseline main.
• Test passes after the fix.
• All 901+ Microsoft.Testing.Platform.UnitTests tests pass across net462/net8.0/net9.0.
• All 3 ServerLoggingTests pass.

[Copilot]

Pull request overview

Fixes a regression in Microsoft.Testing.Platform server-mode host construction where enabling telemetry could crash during TestApplicationBuilder.BuildAsync() by ensuring the build-time TestHostBuilt telemetry event is sent before ServerTelemetry is registered (i.e., before the JSON-RPC message handler is initialized).

Changes:

• Reorders ServerTelemetry registration in BuildServerTestHostAsync to occur after LogTestHostCreatedAsync, preventing ServerTestHost.AssertInitialized failures during build.
• Adds an acceptance regression test that explicitly opts into telemetry and validates the server responds to Initialize.
• Extends server-mode test infrastructure to allow passing additional environment variables to the spawned server process.

Show a summary per file

File	Description
test/IntegrationTests/Microsoft.Testing.Platform.Acceptance.IntegrationTests/ServerMode/ServerModeTestsBase.cs	Adds an overload to inject additional environment variables into the server-mode test process.
test/IntegrationTests/Microsoft.Testing.Platform.Acceptance.IntegrationTests/ServerLoggingTests.cs	Adds a regression test to ensure telemetry-enabled server JSON-RPC mode doesn’t crash during build.
src/Platform/Microsoft.Testing.Platform/Hosts/TestHostBuilder.Modes.cs	Moves ServerTelemetry registration to after the build-time telemetry event is logged to avoid uninitialized JSON-RPC usage.

Copilot's findings

• Files reviewed: 3/3 changed files
• Comments generated: 2

[Evangelink]

🔍 Build Failure Analysis

Summary — The build failed with CS0103: The name 'EnvironmentVariableConstants' does not exist in the current context because two test files are missing the required using Microsoft.Testing.Platform.Helpers; directive.

Root cause: Missing using directive for EnvironmentVariableConstants

The PR's second commit (6297443) updated ServerModeTestsBase.cs and ServerLoggingTests.cs to reference EnvironmentVariableConstants instead of hard-coded string literals. However, both files are missing the using Microsoft.Testing.Platform.Helpers; directive needed to access this internal class.

EnvironmentVariableConstants is an [Embedded] internal class defined in the Platform assembly, so each consuming assembly needs to explicitly import the Microsoft.Testing.Platform.Helpers namespace.

Affected files / errors

• test/IntegrationTests/Microsoft.Testing.Platform.Acceptance.IntegrationTests/ServerMode/ServerModeTestsBase.cs:44 — CS0103: The name 'EnvironmentVariableConstants' does not exist in the current context
• test/IntegrationTests/Microsoft.Testing.Platform.Acceptance.IntegrationTests/ServerLoggingTests.cs:30 — Same root cause (used in the new test method)

Proposed fix

Add using Microsoft.Testing.Platform.Helpers; to the using directives section of both files. This is consistent with other test files in the same project (e.g., DiagnosticTests.cs, IgnoreExitCodeTests.cs) that already reference EnvironmentVariableConstants.

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Build overview

• Build command: ./build.sh --binaryLog
• Exit code: 1 (failure)
• Target framework: net11.0
• Failed project: MSTest.Acceptance.IntegrationTests.csproj
• Build time: 00:03:52.88

All MSBuild errors (1)

Code	Project	File:Line	Message
CS0103	MSTest.Acceptance.IntegrationTests	ServerMode/ServerModeTestsBase.cs:44	The name 'EnvironmentVariableConstants' does not exist in the current context

Note: The error was reported twice by MSBuild (once for each project that references ServerModeTestsBase.cs), but it's the same root cause.

---

_{🤖 Generated by the Build Failure Analysis workflow · commit 6297443}

Generated by Build Failure Analysis for issue #8553 · ● 862.5K · ◷

[Evangelink]

Generated by Build Failure Analysis for issue #8553 · ● 862.5K

Comments that could not be inline-anchored

test/IntegrationTests/Microsoft.Testing.Platform.Acceptance.IntegrationTests/ServerLoggingTests.cs:4

🔧 CS0103 — Add missing using directive for EnvironmentVariableConstants

The new test method RunningInServerJsonRpcModeWithTelemetryEnabled_DoesNotCrashDuringBuildAsync references EnvironmentVariableConstants.DOTNET_CLI_TELEMETRY_OPTOUT and EnvironmentVariableConstants.TESTINGPLATFORM_TELEMETRY_OPTOUT but the file is missing the required namespace import.

using Microsoft.Testing.Platform.Helpers;
using Microsoft.Testing.Platform.ServerMode.IntegrationTests.Messages.V…

</details>

<details><summary>test/IntegrationTests/Microsoft.Testing.Platform.Acceptance.IntegrationTests/ServerMode/ServerModeTestsBase.cs:7</summary>

🔧 **CS0103** — Add missing using directive for `EnvironmentVariableConstants`

This file now references `EnvironmentVariableConstants.TESTINGPLATFORM_EXIT_PROCESS_ON_UNHANDLED_EXCEPTION` on line 44 but is missing the required namespace import.

```suggestion
using Microsoft.Testing.Platform.Acceptance.IntegrationTests;
using Microsoft.Testing.Platform.Helpers;
using Microsoft.Testing.Platform.ServerMode.IntegrationTests.Messages.V100;

[Copilot]

Copilot's findings

• Files reviewed: 4/4 changed files
• Comments generated: 1

[Copilot]

Copilot's findings

• Files reviewed: 4/4 changed files
• Comments generated: 1