Validate unique UIDs when assembling data consumers in BuildTestFrameworkAsync

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

@@ -711,6 +711,8 @@ private static async Task<ITestFramework> BuildTestFrameworkAsync(TestFrameworkB
         {
             if (consumerService is ITestSessionLifetimeHandler handler)
             {
+                // Validate that a handler with the same UID is not already registered
+                testSessionLifetimeHandlers.ValidateUniqueExtension(handler);
                 testSessionLifetimeHandlers.Add(handler);
             }
 
@@ -722,6 +724,8 @@ private static async Task<ITestFramework> BuildTestFrameworkAsync(TestFrameworkB
         // We register the lifetime handler if we're connected to the dotnet test pipe
         if (pushOnlyProtocolDataConsumer is not null)
         {
+            // Validate that a handler with the same UID is not already registered
+            testSessionLifetimeHandlers.ValidateUniqueExtension(pushOnlyProtocolDataConsumer);
             testSessionLifetimeHandlers.Add(pushOnlyProtocolDataConsumer);
         }
 
@@ -735,6 +739,8 @@ private static async Task<ITestFramework> BuildTestFrameworkAsync(TestFrameworkB
         // We register the data consumer handler if we're connected to the dotnet test pipe
         if (pushOnlyProtocolDataConsumer is not null)
         {
+            // Validate that a consumer with the same UID is not already registered
+            dataConsumersBuilder.ValidateUniqueExtension(pushOnlyProtocolDataConsumer);
             dataConsumersBuilder.Add(pushOnlyProtocolDataConsumer);
         }
 
@@ -746,6 +752,8 @@ private static async Task<ITestFramework> BuildTestFrameworkAsync(TestFrameworkB
 
         if (await abortForMaxFailedTestsExtension.IsEnabledAsync().ConfigureAwait(false))
         {
+            // Validate that a consumer with the same UID is not already registered
+            dataConsumersBuilder.ValidateUniqueExtension(abortForMaxFailedTestsExtension);
             dataConsumersBuilder.Add(abortForMaxFailedTestsExtension);
         }
 
@@ -795,6 +803,9 @@ private static async Task RegisterAsServiceOrConsumerOrBothAsync(object service,
                 return;
             }
 
+            // Validate that a consumer with the same UID is not already registered
+            dataConsumersBuilder.ValidateUniqueExtension(dataConsumer);
+
             dataConsumersBuilder.Add(dataConsumer);
         }
 

test/UnitTests/Microsoft.Testing.Platform.UnitTests/TestApplicationBuilderTests.cs

@@ -78,6 +78,30 @@ public async Task TestSessionLifetimeHandle_DuplicatedIdWithCompositeFactory_Sho
         Assert.IsTrue(invalidOperationException.Message.Contains("duplicatedId") && invalidOperationException.Message.Contains(typeof(TestSessionLifetimeHandler).ToString()));
     }
 
+    [TestMethod]
+    public void DataConsumer_AddingDuplicateToExistingList_ShouldFail()
+    {
+        // Simulate the scenario in BuildTestFrameworkAsync where consumers are added to a list
+        List<IDataConsumer> existingConsumers = [new Consumer("duplicatedId")];
+        IDataConsumer newConsumer = new Consumer("duplicatedId");
+
+        // This should throw when trying to add a duplicate
+        InvalidOperationException invalidOperationException = Assert.ThrowsExactly<InvalidOperationException>(() => existingConsumers.ValidateUniqueExtension(newConsumer));
+        Assert.IsTrue(invalidOperationException.Message.Contains("duplicatedId") && invalidOperationException.Message.Contains(typeof(Consumer).ToString()));
+    }
+
+    [TestMethod]
+    public void TestSessionLifetimeHandler_AddingDuplicateToExistingList_ShouldFail()
+    {
+        // Simulate the scenario in BuildTestFrameworkAsync where handlers are added to a list
+        List<ITestSessionLifetimeHandler> existingHandlers = [new TestSessionLifetimeHandler("duplicatedId")];
+        ITestSessionLifetimeHandler newHandler = new TestSessionLifetimeHandler("duplicatedId");
+
+        // This should throw when trying to add a duplicate
+        InvalidOperationException invalidOperationException = Assert.ThrowsExactly<InvalidOperationException>(() => existingHandlers.ValidateUniqueExtension(newHandler));
+        Assert.IsTrue(invalidOperationException.Message.Contains("duplicatedId") && invalidOperationException.Message.Contains(typeof(TestSessionLifetimeHandler).ToString()));
+    }
+
     [DataRow(true)]
     [DataRow(false)]
     [TestMethod]