Change temp folder name used in installer tests (#45523)

Tests in the AppHost.Bundle.Tests assembly seem to randomly fail due to a race condition
with the file system. They try to create separate '0','1','2'... subdirectories to isolate
the published files for each test, but I think what's happening is that files may be
marked for deletion, but then not deleted until a later write. For instance, files in
'2' may be marked for deletion and some may fail a File.Exists check, which leads to
'2' being recreated, at which point deletion may occur, which will cause the current test
to fail due to a concurrent write operation.

This change tries to avoid locking & contention by randomly generating folder names and
using a (hopefully atomically created) lock file to indicate ownership of a particular name.

Fixes #43316

src/installer/tests/Microsoft.NET.HostModel.Tests/AppHost.Bundle.Tests/NetCoreApp3CompatModeTests.cs

@@ -13,19 +13,19 @@
 
 namespace AppHost.Bundle.Tests
 {
-    public class NetCoreApp3CompatModeTests : BundleTestBase, IClassFixture<NetCoreApp3CompatModeTests.SharedTestState>
+    public class NetCoreApp3CompatModeTests : BundleTestBase, IClassFixture<SingleFileSharedState>
     {
-        private SharedTestState sharedTestState;
+        private SingleFileSharedState sharedTestState;
 
-        public NetCoreApp3CompatModeTests(SharedTestState fixture)
+        public NetCoreApp3CompatModeTests(SingleFileSharedState fixture)
         {
             sharedTestState = fixture;
         }
 
         [Fact]
         public void Bundle_Is_Extracted()
         {
-            var fixture = sharedTestState.SingleFileTestFixture.Copy();
+            var fixture = sharedTestState.TestFixture.Copy();
             UseSingleFileSelfContainedHost(fixture);
             Bundler bundler = BundleHelper.BundleApp(fixture, out string singleFile, BundleOptions.BundleAllContent);
             var extractionBaseDir = BundleHelper.GetExtractionRootDir(fixture);
@@ -52,20 +52,5 @@ public void Bundle_Is_Extracted()
                 .ToArray();
             extractionDir.Should().HaveFiles(publishedFiles);
         }
-
-        public class SharedTestState : SharedTestStateBase, IDisposable
-        {
-            public TestProjectFixture SingleFileTestFixture { get; set; }
-
-            public SharedTestState()
-            {
-                SingleFileTestFixture = PreparePublishedSelfContainedTestProject("SingleFileApiTests");
-            }
-
-            public void Dispose()
-            {
-                SingleFileTestFixture.Dispose();
-            }
-        }
     }
 }

src/installer/tests/Microsoft.NET.HostModel.Tests/AppHost.Bundle.Tests/SingleFileApiTests.cs

@@ -8,11 +8,11 @@
 
 namespace AppHost.Bundle.Tests
 {
-    public class SingleFileApiTests : BundleTestBase, IClassFixture<SingleFileApiTests.SharedTestState>
+    public class SingleFileApiTests : BundleTestBase, IClassFixture<SingleFileSharedState>
     {
-        private SharedTestState sharedTestState;
+        private SingleFileSharedState sharedTestState;
 
-        public SingleFileApiTests(SharedTestState fixture)
+        public SingleFileApiTests(SingleFileSharedState fixture)
         {
             sharedTestState = fixture;
         }
@@ -120,23 +120,5 @@ public void AppContext_Native_Search_Dirs_Contains_Bundle_And_Extraction_Dirs()
                 .And.HaveStdOutContaining(extractionDir)
                 .And.HaveStdOutContaining(bundleDir);
         }
-
-        public class SharedTestState : SharedTestStateBase, IDisposable
-        {
-            public TestProjectFixture TestFixture { get; set; }
-
-            public SharedTestState()
-            {
-                // We include mockcoreclr in our project to test native binaries extraction.
-                string mockCoreClrPath = Path.Combine(RepoDirectories.Artifacts, "corehost_test",
-                    RuntimeInformationExtensions.GetSharedLibraryFileNameForCurrentPlatform("mockcoreclr"));
-                TestFixture = PreparePublishedSelfContainedTestProject("SingleFileApiTests", $"/p:AddFile={mockCoreClrPath}");
-            }
-
-            public void Dispose()
-            {
-                TestFixture.Dispose();
-            }
-        }
     }
 }

src/installer/tests/Microsoft.NET.HostModel.Tests/AppHost.Bundle.Tests/SingleFileSharedState.cs

@@ -0,0 +1,29 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.IO;
+using Microsoft.DotNet.CoreSetup.Test;
+using Xunit;
+using static AppHost.Bundle.Tests.BundleTestBase;
+
+namespace AppHost.Bundle.Tests
+{
+    public class SingleFileSharedState : SharedTestStateBase, IDisposable
+    {
+        public TestProjectFixture TestFixture { get; set; }
+
+        public SingleFileSharedState()
+        {
+            // We include mockcoreclr in our project to test native binaries extraction.
+            string mockCoreClrPath = Path.Combine(RepoDirectories.Artifacts, "corehost_test",
+                RuntimeInformationExtensions.GetSharedLibraryFileNameForCurrentPlatform("mockcoreclr"));
+            TestFixture = PreparePublishedSelfContainedTestProject("SingleFileApiTests", $"/p:AddFile={mockCoreClrPath}");
+        }
+
+        public void Dispose()
+        {
+            TestFixture.Dispose();
+        }
+    }
+}

src/installer/tests/TestUtils/TestArtifact.cs

@@ -1,11 +1,13 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+#nullable enable
+
 using Microsoft.DotNet.CoreSetup.Test.HostActivation;
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
-using System.Threading;
 
 namespace Microsoft.DotNet.CoreSetup.Test
 {
@@ -22,7 +24,7 @@ public class TestArtifact : IDisposable
         {
             return _repoDirectoriesProvider.Value.GetTestContextVariable(TestArtifactDirectoryEnvironmentVariable)
                    ?? Path.Combine(AppContext.BaseDirectory, TestArtifactDirectoryEnvironmentVariable);
-        });
+        }, isThreadSafe: true);
 
         public static bool PreserveTestRuns() => _preserveTestRuns.Value;
         public static string TestArtifactsPath => _testArtifactsPath.Value;
@@ -32,7 +34,7 @@ public class TestArtifact : IDisposable
 
         private readonly List<TestArtifact> _copies = new List<TestArtifact>();
 
-        public TestArtifact(string location, string name = null)
+        public TestArtifact(string location, string? name = null)
         {
             Location = location;
             Name = name ?? Path.GetFileName(Location);
@@ -57,7 +59,18 @@ public virtual void Dispose()
         {
             if (!PreserveTestRuns() && Directory.Exists(Location))
             {
-                Directory.Delete(Location, true);
+                try
+                {
+                    Directory.Delete(Location, true);
+
+                    // Delete lock file last
+                    Debug.Assert(!Directory.Exists(Location));
+                    var lockPath = Directory.GetParent(Location) + ".lock";
+                    File.Delete(lockPath);
+                } catch (Exception e)
+                {
+                    Console.WriteLine("delete failed" + e);
+                }
             }
 
             foreach (TestArtifact copy in _copies)
@@ -68,21 +81,30 @@ public virtual void Dispose()
             _copies.Clear();
         }
 
-        private static readonly object _pathCountLock = new object();
         protected static string GetNewTestArtifactPath(string artifactName)
         {
-            int projectCount = 0;
-            string projectCountDir() => Path.Combine(TestArtifactsPath, projectCount.ToString(), artifactName);
-
-            for (; Directory.Exists(projectCountDir()); projectCount++);
-
-            lock (_pathCountLock)
+            Exception? lastException = null;
+            for (int i = 0; i < 10; i++)
             {
-                string projectDirectory;
-                for (; Directory.Exists(projectDirectory = projectCountDir()); projectCount++);
-                FileUtils.EnsureDirectoryExists(projectDirectory);
-                return projectDirectory;
+                var parentPath = Path.Combine(TestArtifactsPath, Path.GetRandomFileName());
+                // Create a lock file next to the target folder
+                var lockPath = parentPath + ".lock";
+                var artifactPath = Path.Combine(parentPath, artifactName);
+                try
+                {
+                    File.Open(lockPath, FileMode.CreateNew, FileAccess.Write).Dispose();
+                }
+                catch (Exception e)
+                {
+                    // Lock file cannot be created, potential collision
+                    lastException = e;
+                    continue;
+                }
+                Directory.CreateDirectory(artifactPath);
+                return artifactPath;
             }
+            Debug.Assert(lastException != null);
+            throw lastException;
         }
 
         protected static void CopyRecursive(string sourceDirectory, string destinationDirectory, bool overwrite = false)