avoid code duplication for disabling parallelization with xUnit (#62132)

The collection definitions must be in the same assembly as the test that uses them

Author: adamsitnik

src/libraries/Common/tests/TestUtilities/System/DisableParallelization.cs

@@ -0,0 +1,12 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using Xunit;
+
+namespace System
+{
+    // The collection definitions must be in the same assembly as the test that uses them.
+    // So please use "Compile Include" in the project file to include this class.
+    [CollectionDefinition(nameof(DisableParallelization), DisableParallelization = true)]
+    public class DisableParallelization { }
+}

src/libraries/System.ComponentModel.TypeConverter/tests/MemberDescriptorTests.cs

@@ -9,11 +9,8 @@
 
 namespace System.ComponentModel.Tests
 {
-    [CollectionDefinition("NoParallelTests", DisableParallelization = true)]
-    public partial class NoParallelTests { }
-
     // Mutable static comparision in the implementation
-    [Collection("NoParallelTests")]
+    [Collection(nameof(DisableParallelization))]
     public class MemberDescriptorTests
     {
         [Theory]

src/libraries/System.ComponentModel.TypeConverter/tests/ReflectionCachesUpdateHandlerTests.cs

@@ -7,7 +7,7 @@
 namespace System.ComponentModel.Tests
 {
     [SimpleUpdateTest]
-    [Collection("NoParallelTests")] // Clears the cache which disrupts concurrent tests
+    [Collection(nameof(DisableParallelization))] // Clears the cache which disrupts concurrent tests
     public class ReflectionCachesUpdateHandlerTests
     {
         [Fact]

src/libraries/System.ComponentModel.TypeConverter/tests/System.ComponentModel.TypeConverter.Tests.csproj

@@ -153,6 +153,8 @@
     <Compile Include="Security\Authentication\ExtendedProtection\ExtendedProtectionPolicyTypeConverterTests.cs" />
     <Compile Include="XTypeDescriptionProviderTests.cs" />
 
+    <Compile Include="$(CommonTestPath)TestUtilities\System\DisableParallelization.cs"
+        Link="Common\TestUtilities\System\DisableParallelization.cs" />
     <TrimmerRootDescriptor Include="$(ILLinkDescriptorsPath)ILLink.Descriptors.Castle.xml" />
   </ItemGroup>
   <ItemGroup>

src/libraries/System.ComponentModel.TypeConverter/tests/TypeDescriptorTests.cs

@@ -10,7 +10,7 @@
 
 namespace System.ComponentModel.Tests
 {
-    [Collection("NoParallelTests")] // manipulates cache
+    [Collection(nameof(DisableParallelization))] // manipulates cache
     public class TypeDescriptorTests
     {
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsNotMonoAOT))] // Mock will try to JIT 

src/libraries/System.IO.FileSystem.Watcher/tests/FileSystemWatcher.unit.cs

@@ -1086,7 +1086,7 @@ public void FileSystemWatcher_ModifyFiltersConcurrentWithEvents()
         }
     }
 
-    [Collection("NoParallelTests")]
+    [Collection(nameof(DisableParallelization))]
     public partial class DangerousFileSystemWatcherTests : FileSystemWatcherTest
     {
         private readonly ITestOutputHelper _output;

src/libraries/System.IO.FileSystem.Watcher/tests/System.IO.FileSystem.Watcher.Tests.csproj

@@ -35,6 +35,8 @@
              Link="Common\System\IO\TempFile.cs" />
     <Compile Include="$(CommonTestPath)System\IO\TempDirectory.cs"
              Link="Common\System\IO\TempDirectory.cs" />
+    <Compile Include="$(CommonTestPath)TestUtilities\System\DisableParallelization.cs"
+             Link="Common\TestUtilities\System\DisableParallelization.cs" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetsLinux)' == 'true' or '$(TargetsOSX)' == 'true' or '$(TargetsiOS)' == 'true' or '$(TargetstvOS)' == 'true'">
     <Compile Include="FileSystemWatcher.Unix.cs" />

src/libraries/System.IO.FileSystem.Watcher/tests/Utility/FileSystemWatcherTest.cs

@@ -11,9 +11,6 @@
 
 namespace System.IO.Tests
 {
-    [CollectionDefinition("NoParallelTests", DisableParallelization = true)]
-    public partial class NoParallelTests { }
-
     public abstract partial class FileSystemWatcherTest : FileCleanupTestBase
     {
         // Events are reported asynchronously by the OS, so allow an amount of time for

src/libraries/System.IO.FileSystem/tests/DisabledFileLockingTests/System.IO.FileSystem.DisabledFileLocking.Tests.csproj

@@ -20,6 +20,7 @@
     <Compile Include="..\PortedCommon\IOInputs.cs" />
     <Compile Include="..\PortedCommon\IOServices.cs" />
     <Compile Include="$(CommonTestPath)System\IO\PathFeatures.cs" Link="Common\System\IO\PathFeatures.cs" />
+    <Compile Include="$(CommonTestPath)TestUtilities\System\DisableParallelization.cs" Link="Common\TestUtilities\System\DisableParallelization.cs" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetsUnix)' == 'true'">
     <Compile Remove="..\**\*.Windows.cs" />

src/libraries/System.IO.FileSystem/tests/FileStream/FileStreamConformanceTests.Windows.cs

@@ -77,7 +77,7 @@ protected override string GetTestFilePath(int? index = null, [CallerMemberName]
     }
 
     [PlatformSpecific(TestPlatforms.Windows)] // the test setup is Windows-specifc
-    [Collection("NoParallelTests")] // don't run in parallel, as file sharing logic is not thread-safe
+    [Collection(nameof(DisableParallelization))] // don't run in parallel, as file sharing logic is not thread-safe
     [OuterLoop("Requires admin privileges to create a file share")]
     [ConditionalClass(typeof(UncFilePathFileStreamStandaloneConformanceTests), nameof(CanShareFiles))]
     public class UncFilePathFileStreamStandaloneConformanceTests : UnbufferedAsyncFileStreamStandaloneConformanceTests