Fix "Found multiple properties of type 'Microsoft.Testing.Platform.Ex…

src/Platform/Microsoft.Testing.Extensions.VSTestBridge/ObjectModel/ObjectModelConverters.cs

@@ -162,21 +162,35 @@ public static TestNode ToTestNode(this TestResult testResult, bool isTrxEnabled,
 
         testNode.Properties.Add(new TimingProperty(new(testResult.StartTime, testResult.EndTime, testResult.Duration), []));
 
+        var standardErrorMessages = new List<string>();
+        var standardOutputMessages = new List<string>();
         foreach (TestResultMessage testResultMessage in testResult.Messages)
         {
             if (testResultMessage.Category == TestResultMessage.StandardErrorCategory)
             {
-                testNode.Properties.Add(new SerializableKeyValuePairStringProperty("vstest.TestCase.StandardError", testResultMessage.Text ?? string.Empty));
-                testNode.Properties.Add(new StandardErrorProperty(testResultMessage.Text ?? string.Empty));
+                string message = testResultMessage.Text ?? string.Empty;
+                testNode.Properties.Add(new SerializableKeyValuePairStringProperty("vstest.TestCase.StandardError", message));
+                standardErrorMessages.Add(message);
             }
 
             if (testResultMessage.Category == TestResultMessage.StandardOutCategory)
             {
-                testNode.Properties.Add(new SerializableKeyValuePairStringProperty("vstest.TestCase.StandardOutput", testResultMessage.Text ?? string.Empty));
-                testNode.Properties.Add(new StandardOutputProperty(testResultMessage.Text ?? string.Empty));
+                string message = testResultMessage.Text ?? string.Empty;
+                testNode.Properties.Add(new SerializableKeyValuePairStringProperty("vstest.TestCase.StandardOutput", message));
+                standardOutputMessages.Add(message);
             }
         }
 
+        if (standardErrorMessages.Count > 0)
+        {
+            testNode.Properties.Add(new StandardErrorProperty(string.Join(Environment.NewLine, standardErrorMessages)));
+        }
+
+        if (standardOutputMessages.Count > 0)
+        {
+            testNode.Properties.Add(new StandardOutputProperty(string.Join(Environment.NewLine, standardOutputMessages)));
+        }
+
         return testNode;
     }
 

test/IntegrationTests/MSTest.Acceptance.IntegrationTests/OutputTests.cs

@@ -0,0 +1,88 @@
+// 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.Acceptance.IntegrationTests;
+using Microsoft.Testing.Platform.Acceptance.IntegrationTests.Helpers;
+
+namespace MSTest.Acceptance.IntegrationTests;
+
+[TestGroup]
+public sealed class OutputTests : AcceptanceTestBase
+{
+    private readonly TestAssetFixture _testAssetFixture;
+
+    public OutputTests(ITestExecutionContext testExecutionContext, TestAssetFixture testAssetFixture)
+        : base(testExecutionContext) => _testAssetFixture = testAssetFixture;
+
+    [ArgumentsProvider(nameof(TargetFrameworks.All), typeof(TargetFrameworks))]
+    public async Task DetailedOutputIsAsExpected(string tfm)
+    {
+        var testHost = TestHost.LocateFrom(_testAssetFixture.ProjectPath, TestAssetFixture.ProjectName, tfm);
+        TestHostResult testHostResult = await testHost.ExecuteAsync("--output detailed");
+
+        // Assert
+        testHostResult.AssertOutputContains("Assert.AreEqual failed. Expected:<1>. Actual:<2>.");
+        testHostResult.AssertOutputContains("""
+              Standard output
+                Console message
+                TestContext Messages:
+                TestContext message
+              Error output
+            """);
+    }
+
+    [TestFixture(TestFixtureSharingStrategy.PerTestGroup)]
+    public sealed class TestAssetFixture(AcceptanceFixture acceptanceFixture) : TestAssetFixtureBase(acceptanceFixture.NuGetGlobalPackagesFolder)
+    {
+        public const string ProjectName = "TestOutput";
+
+        public string ProjectPath => GetAssetPath(ProjectName);
+
+        public override IEnumerable<(string ID, string Name, string Code)> GetAssetsToGenerate()
+        {
+            yield return (ProjectName, ProjectName,
+                SourceCode
+                .PatchTargetFrameworks(TargetFrameworks.All)
+                .PatchCodeWithReplace("$MSTestVersion$", MSTestVersion));
+        }
+
+        private const string SourceCode = """
+#file TestOutput.csproj
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <EnableMSTestRunner>true</EnableMSTestRunner>
+    <TargetFrameworks>$TargetFrameworks$</TargetFrameworks>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="MSTest.TestAdapter" Version="$MSTestVersion$" />
+    <PackageReference Include="MSTest.TestFramework" Version="$MSTestVersion$" />
+  </ItemGroup>
+
+</Project>
+
+#file UnitTest1.cs
+using System;
+using System.Diagnostics;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+[TestClass]
+public class UnitTest1
+{
+    public TestContext TestContext { get; set; }
+
+    [TestMethod]
+    public void TestMethod()
+    {
+        Debug.WriteLine("Debug message");
+        Console.WriteLine("Console message");
+        TestContext.WriteLine("TestContext message");
+
+        Assert.AreEqual(1, 2);
+    }
+}
+""";
+    }
+}

test/UnitTests/Microsoft.Testing.Extensions.VSTestBridge.UnitTests/ObjectModel/ObjectModelConvertersTests.cs

@@ -252,4 +252,42 @@ public void ToTestNode_WhenTestResultHasTraits_TestNodePropertiesContainIt()
         Assert.IsTrue(errorTestNodeStateProperties[0].Pairs[0].Key == "key");
         Assert.IsTrue(errorTestNodeStateProperties[0].Pairs[0].Value == "value");
     }
+
+    public void ToTestNode_WhenTestResultHasMultipleStandardOutputMessages_TestNodePropertiesHasASingleOne()
+    {
+        TestResult testResult = new(new TestCase("SomeFqn", new("executor://uri", UriKind.Absolute), "source.cs"))
+        {
+            DisplayName = "TestName",
+            Messages =
+            {
+                new TestResultMessage(TestResultMessage.StandardOutCategory, "message1"),
+                new TestResultMessage(TestResultMessage.StandardOutCategory, "message2"),
+            },
+        };
+
+        var testNode = testResult.ToTestNode(false, VSTestClient);
+
+        StandardOutputProperty[] standardOutputProperties = testNode.Properties.OfType<StandardOutputProperty>().ToArray();
+        Assert.IsTrue(standardOutputProperties.Length == 1);
+        Assert.AreEqual($"message1{Environment.NewLine}message2", standardOutputProperties[0].StandardOutput);
+    }
+
+    public void ToTestNode_WhenTestResultHasMultipleStandardErrorMessages_TestNodePropertiesHasASingleOne()
+    {
+        TestResult testResult = new(new TestCase("SomeFqn", new("executor://uri", UriKind.Absolute), "source.cs"))
+        {
+            DisplayName = "TestName",
+            Messages =
+            {
+                new TestResultMessage(TestResultMessage.StandardErrorCategory, "message1"),
+                new TestResultMessage(TestResultMessage.StandardErrorCategory, "message2"),
+            },
+        };
+
+        var testNode = testResult.ToTestNode(false, VSTestClient);
+
+        StandardErrorProperty[] standardErrorProperties = testNode.Properties.OfType<StandardErrorProperty>().ToArray();
+        Assert.IsTrue(standardErrorProperties.Length == 1);
+        Assert.AreEqual($"message1{Environment.NewLine}message2", standardErrorProperties[0].StandardError);
+    }
 }