Fix multi tfm project tests (#3425)

Co-authored-by: Amaury Levé <[email protected]>

test/Microsoft.TestPlatform.AcceptanceTests/MultitargetingTestHostTests.cs

@@ -1,6 +1,8 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
+using System.Collections.Generic;
+
 using Microsoft.TestPlatform.TestUtilities;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
@@ -17,14 +19,22 @@ public class MultitargetingTestHostTests : AcceptanceTestBase
     // xUnit supports net452 onwards, so that is why this starts at net452, I also don't test all framework versions
     [NetCoreRunner(NETFX452_48)]
     [NetFrameworkRunner(NETFX452_48)]
-    public void RunningTestWithAFailingDebugAssertDoesNotCrashTheHostingProcess(RunnerInfo runnerInfo)
+    public void TestRunInATesthostThatTargetsTheirChosenNETFramework(RunnerInfo runnerInfo)
     {
         SetTestEnvironment(_testEnvironment, runnerInfo);
         using var tempDir = new TempDirectory();
 
         var assemblyPath = BuildMultipleAssemblyPath("MultitargetedNetFrameworkProject.dll").Trim('\"');
         var arguments = PrepareArguments(assemblyPath, null, null, FrameworkArgValue, runnerInfo.InIsolationValue, resultsDirectory: tempDir.Path);
-        InvokeVsTest(arguments);
+
+        // Tell the test project which target framework we are expecting it to run as.
+        // It has this value conditionally compiled, so it can compare it.
+        var env = new Dictionary<string, string>
+        {
+            ["EXPECTED_TARGET_FRAMEWORK"] = runnerInfo.TargetFramework
+        };
+
+        InvokeVsTest(arguments, env);
 
         ValidateSummaryStatus(passedTestsCount: 1, failedTestsCount: 0, 0);
     }

test/TestAssets/MultitargetedNetFrameworkProject/UnitTest1.cs

@@ -2,7 +2,9 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using System;
+using System.Diagnostics;
 using System.IO;
+using System.Linq;
 using System.Net.Security;
 using System.Security.Authentication;
 
@@ -48,43 +50,12 @@ public class UnitTest1
 #if NET48
         public string TargetFramework { get; } = "NET48";
 #endif
-
-        // Using xUnit here because MSTest uses AppDomains by default and fixes this problem for us
-        // as long as the appdomains are enabled and modern .NET Framework is installed.
         [Fact]
         public void FailsUntilNet462ButPassesOnNewerNetFramework()
         {
-            Exception exception = null;
-            try
-            {
-                MemoryStream stream = new MemoryStream();
-                SslStream sslStream = new SslStream(stream);
-
-                // this throws SSLException on net451-net462, on net471 onwards it passes so we can use it to test that we target correctly
-                sslStream.BeginAuthenticateAsClient("microsoft.com", null, SslProtocols.None, false, new AsyncCallback(ProcessInformation), null);
-            }
-            catch (Exception ex)
-            {
-                exception = ex;
-            }
+            var expected = Environment.GetEnvironmentVariable("EXPECTED_TARGET_FRAMEWORK");
 
-            switch (TargetFramework)
-            {
-                case "NET451":
-                case "NET452":
-                case "NET46":
-                case "NET461":
-                case "NET462":
-                    Assert.NotNull(exception);
-                    break;
-                default:
-                    Assert.Null(exception);
-                    break;
-            }
-        }
-
-        static void ProcessInformation(IAsyncResult result)
-        {
+            Assert.Equal(expected, TargetFramework, ignoreCase: true);
         }
     }
 }