Support Helix testing on CentOS Stream 9

eng/pipelines/templates/jobs/sdk-job-matrix.yml

@@ -45,9 +45,7 @@ parameters:
     container: centosStream9
     helixTargetContainer: $(helixTargetContainerPrefix)centos-stream9-helix
     osProperties: /p:OSName=linux
-    # Skipping all container-based testing for now.
-    # See: https://github.com/dotnet/sdk/issues/40935
-    runTests: false
+    runTests: true
   - categoryName: ContainerBased
     container: debian12Amd64
     helixTargetContainer: $(helixTargetContainerPrefix)debian-11-helix-amd64

test/Microsoft.NET.TestFramework/EnvironmentInfo.cs

@@ -101,6 +101,13 @@ public static bool SupportsTargetFramework(string targetFramework)
                         return false;
                     }
                 }
+                else if (osId.Equals("centos", StringComparison.OrdinalIgnoreCase))
+                {
+                    if (nugetFramework.Version < new Version(2, 0, 0, 0))
+                    {
+                        return false;
+                    }
+                }
                 else if (osId.Equals("debian", StringComparison.OrdinalIgnoreCase))
                 {
                     if (nugetFramework.Version < new Version(2, 0, 0, 0))

test/dotnet.Tests/CommandTests/Workload/Restore/GivenDotnetWorkloadRestore.cs

@@ -60,6 +60,14 @@ public void ProjectsThatDoNotSupportWorkloadsAndAreTransitivelyReferencedDoNotBr
 
     private bool IsRunningInContainer()
     {
-        return File.Exists("/.dockerenv") && (RuntimeInformation.OSDescription.Contains("Ubuntu") || RuntimeInformation.OSDescription.Contains("Debian"));
+        if (!File.Exists("/.dockerenv"))
+        {
+            return false;
+        }
+
+        string osDescription = RuntimeInformation.OSDescription.ToLowerInvariant();
+        return osDescription.Contains("centos") ||
+               osDescription.Contains("debian") ||
+               osDescription.Contains("ubuntu");
     }
 }