Fix InvalidOperationException in BuildServerTestHostAsync when telemetry is enabled

src/Platform/Microsoft.Testing.Platform/Hosts/TestHostBuilder.Modes.cs

@@ -217,26 +217,32 @@ private async Task<IHost> BuildServerTestHostAsync(BuildContext context, NamedPi
             (TestFrameworkManager)TestFramework!,
             (TestHostManager)TestHost);
 
-        // Register ServerTelemetry in the service provider so that all telemetry events in server mode
-        // are forwarded to the client via JSON-RPC. This replaces the NopTelemetryService registered
-        // earlier in SetupCommonServicesAsync. This is always registered regardless of whether platform
-        // telemetry is enabled or disabled, because server-mode telemetry is a protocol concern (JSON-RPC
-        // forwarding to the client), not a data-collection concern.
-        context.ServiceProvider.ReplaceService<ITelemetryCollector>(new ServerTelemetry(serverTestHost));
-
 #pragma warning disable CA1416 // Preserve existing browser behavior while splitting the method.
         IHost actualTestHost = testControllerConnection is not null
             ? new TestHostControlledHost(testControllerConnection, serverTestHost, context.TestApplicationCancellationTokenSource.CancellationToken)
             : serverTestHost;
 #pragma warning restore CA1416 // Preserve existing browser behavior while splitting the method.
 
+        // The TestHostBuilt telemetry event must be sent through the collector previously registered
+        // by TelemetryManager in SetupCommonServicesAsync (a real collector when telemetry is opted in,
+        // or NopTelemetryService when opted out) because the ServerTestHost JSON-RPC message handler is
+        // not yet initialized at this point (it is created later inside ServerTestHost.InternalRunAsync).
+        // Sending it through ServerTelemetry here would throw InvalidOperationException via
+        // ServerTestHost.AssertInitialized.
         await LogTestHostCreatedAsync(
             context.ServiceProvider,
             TelemetryProperties.ApplicationMode.Server,
             context.BuilderMetrics,
             context.SystemClock.UtcNow,
             context.TestApplicationCancellationTokenSource.CancellationToken).ConfigureAwait(false);
 
+        // Register ServerTelemetry in the service provider so that all telemetry events raised at runtime
+        // in server mode are forwarded to the client via JSON-RPC. This replaces the collector registered
+        // earlier by TelemetryManager in SetupCommonServicesAsync. This is always registered regardless of
+        // whether platform telemetry is enabled or disabled, because server-mode telemetry is a protocol
+        // concern (JSON-RPC forwarding to the client), not a data-collection concern.
+        context.ServiceProvider.ReplaceService<ITelemetryCollector>(new ServerTelemetry(serverTestHost));
+
         CompleteBuilderActivity(context.BuilderActivity, testControllerConnection is not null ? nameof(TestHostControlledHost) : nameof(ServerTestHost));
         return actualTestHost;
     }

test/IntegrationTests/MSTest.Acceptance.IntegrationTests/MSTest.Acceptance.IntegrationTests.csproj

@@ -10,6 +10,7 @@
   <ItemGroup>
     <!-- Embedded helpers from Microsoft.Testing.Platform -->
     <Compile Include="$(RepoRoot)src\Platform\Microsoft.Testing.Platform\Helpers\ApplicationStateGuard.cs" Link="Helpers\ApplicationStateGuard.cs" />
+    <Compile Include="$(RepoRoot)src\Platform\Microsoft.Testing.Platform\Helpers\EnvironmentVariableConstants.cs" Link="Helpers\EnvironmentVariableConstants.cs" />
     <Compile Include="$(RepoRoot)src\Platform\Microsoft.Testing.Platform\Helpers\ExitCodes.cs" Link="Helpers\ExitCodes.cs" />
     <Compile Include="$(RepoRoot)src\Platform\Microsoft.Testing.Platform\Resources\PlatformResources.cs" Link="Resources\PlatformResources.cs" />
   </ItemGroup>

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

@@ -1,4 +1,4 @@
-// Copyright (c) Microsoft Corporation. All rights reserved.
+// Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using Microsoft.Testing.Platform.ServerMode.IntegrationTests.Messages.V100;
@@ -10,6 +10,35 @@ namespace Microsoft.Testing.Platform.Acceptance.IntegrationTests;
 [TestClass]
 public sealed partial class ServerLoggingTests : ServerModeTestsBase<ServerLoggingTests.TestAssetFixture>
 {
+    [TestMethod]
+    public async Task RunningInServerJsonRpcModeWithTelemetryEnabled_DoesNotCrashDuringBuildAsync()
+    {
+        // Regression test: PR #8211 registered ServerTelemetry in the service provider BEFORE
+        // calling LogTestHostCreatedAsync. Because ServerTestHost's JSON-RPC message handler 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().
+        //
+        // This test forces telemetry to be opted in (overriding any DOTNET_CLI_TELEMETRY_OPTOUT
+        // inherited from Arcade in CI) so the LogTestHostCreatedAsync path is actually
+        // executed and would crash without the fix.
+        string tfm = TargetFrameworks.NetCurrent;
+        var testHost = TestInfrastructure.TestHost.LocateFrom(AssetFixture.TargetAssetPath, "ServerLoggingTests", tfm);
+        Dictionary<string, string?> telemetryEnabledEnv = new()
+        {
+            [EnvironmentVariableConstants.DOTNET_CLI_TELEMETRY_OPTOUT] = "0",
+            [EnvironmentVariableConstants.TESTINGPLATFORM_TELEMETRY_OPTOUT] = "0",
+        };
+        using TestingPlatformClient jsonClient = await StartAsServerAndConnectToTheClientAsync(testHost, telemetryEnabledEnv);
+
+        // If the host crashed during BuildAsync, Initialize would never get a response and time out.
+        InitializeResponse initializeResponseArgs = await jsonClient.Initialize();
+        Assert.IsNotNull(initializeResponseArgs);
+
+        await jsonClient.Exit();
+    }
+
     [TestMethod]
     public async Task RunningInServerJsonRpcModeShouldHaveOutputDeviceLogsPushedToTestExplorer()
     {

test/IntegrationTests/Microsoft.Testing.Platform.Acceptance.IntegrationTests/ServerMode/ServerModeTestsBase.cs

@@ -5,6 +5,7 @@
 using System.Net.Sockets;
 
 using Microsoft.Testing.Platform.Acceptance.IntegrationTests;
+using Microsoft.Testing.Platform.Helpers;
 using Microsoft.Testing.Platform.ServerMode.IntegrationTests.Messages.V100;
 
 namespace MSTest.Acceptance.IntegrationTests.Messages.V100;
@@ -21,7 +22,10 @@ namespace MSTest.Acceptance.IntegrationTests.Messages.V100;
         { "DOTNET_MULTILEVEL_LOOKUP", "0" },
     };
 
-    protected async Task<TestingPlatformClient> StartAsServerAndConnectToTheClientAsync(TestHost testHost)
+    protected Task<TestingPlatformClient> StartAsServerAndConnectToTheClientAsync(TestHost testHost)
+        => StartAsServerAndConnectToTheClientAsync(testHost, additionalEnvironmentVariables: null);
+
+    protected async Task<TestingPlatformClient> StartAsServerAndConnectToTheClientAsync(TestHost testHost, IReadOnlyDictionary<string, string?>? additionalEnvironmentVariables)
     {
         var environmentVariables = new Dictionary<string, string?>(DefaultEnvironmentVariables);
         foreach (DictionaryEntry entry in Environment.GetEnvironmentVariables())
@@ -37,7 +41,16 @@ protected async Task<TestingPlatformClient> StartAsServerAndConnectToTheClientAs
         }
 
         // We expect to not fail for unhandled exception in server mode for IDE needs.
-        environmentVariables.Add("TESTINGPLATFORM_EXIT_PROCESS_ON_UNHANDLED_EXCEPTION", "0");
+        // Use indexer assignment so that an inherited value (if any) is safely overridden.
+        environmentVariables[EnvironmentVariableConstants.TESTINGPLATFORM_EXIT_PROCESS_ON_UNHANDLED_EXCEPTION] = "0";
+
+        if (additionalEnvironmentVariables is not null)
+        {
+            foreach (KeyValuePair<string, string?> kvp in additionalEnvironmentVariables)
+            {
+                environmentVariables[kvp.Key] = kvp.Value;
+            }
+        }
 
         // To attach to the server on startup
         // environmentVariables.Add(EnvironmentVariableConstants.TESTINGPLATFORM_LAUNCH_ATTACH_DEBUGGER, "1");