Remove Polyfill NuGet package dependency by Evangelink · Pull Request #7597 · microsoft/testfx

Evangelink · 2026-03-24T10:32:34Z

Replace the Polyfill NuGet package with a self-contained eng/Polyfills.cs file and project-specific polyfill extension methods.

Changes

Remove Polyfill PackageReference from all 35 csproj files
Remove Polyfill configuration (PolyEnsure, PolyGuard, PolyStringInterpolation, PolyUseEmbeddedAttribute) from Directory.Build.props
Remove PackageVersion entry from Directory.Packages.props
Remove global <Using Include="Polyfills" /> directives from 12 csproj files
Remove explicit using Polyfills; from source files
Remove Polyfill-specific GlobalSuppressions entry

Replacements

eng/Polyfills.cs — Shared polyfill types and attributes for older TFMs (netstandard2.0, net462): nullable attributes, compiler attributes, ExperimentalAttribute, Index/Range, Lock, OperatingSystem, UnreachableException, Ensure helper, etc.
Project-specific polyfill extensions — Extension methods scoped to projects that need them to avoid IVT ambiguity:
- src/Platform/Microsoft.Testing.Platform/Helpers/KeyValuePairDeconstruct.cs
- src/Platform/Microsoft.Testing.Extensions.TrxReport.Abstractions/PolyfillExtensions.cs
- src/TestFramework/TestFramework/Internal/PolyfillExtensions.cs
- src/Adapter/MSTestAdapter.PlatformServices/PolyfillExtensions.cs
- src/Analyzers/MSTest.Analyzers/RoslynAnalyzerHelpers/AnalyzerPolyfillExtensions.cs

Call-site fixes

Fixed code that relied on Polyfill-provided APIs not available on older TFMs: SHA256.HashData, Convert.ToHexStringLower, Environment.ProcessId, File.Move (3-arg), File.ReadAllTextAsync, Enum.Parse<T>, Enum.GetNames<T>, Enum.IsDefined<T>, Enum.GetValues<T>, XElement.LoadAsync, XDocument.SaveAsync, Type.IsGenericMethodParameter, string.Join(char, ...), ConcurrentBag.Clear, ConcurrentDictionary.GetOrAdd (3-arg), and TextWriter.FlushAsync(CancellationToken).

Fixes #7596

Replace the Polyfill NuGet package with a self-contained eng/Polyfills.cs file and project-specific polyfill extensions. - Remove Polyfill PackageReference from all 35 csproj files - Remove Polyfill configuration (PolyEnsure, PolyGuard, etc.) from Directory.Build.props - Remove PackageVersion from Directory.Packages.props - Remove global using Polyfills directives from csproj files - Add eng/Polyfills.cs with type stubs and attributes for older TFMs - Add project-specific polyfill extension methods where needed - Fix call sites for APIs not available on netstandard2.0/net462 Fixes #7596

Copilot

Pull request overview

This PR removes the third-party Polyfill NuGet dependency across the repo and replaces it with a shared, source-included polyfill implementation (eng/Polyfills.cs) plus a few project-scoped polyfill extension files to keep older TFMs building cleanly.

Changes:

Removed Polyfill PackageReference entries (and related MSBuild config/global usings) across projects.
Added eng/Polyfills.cs and wired it into builds via Directory.Build.props.
Updated call sites to avoid APIs/overloads not available on older TFMs (e.g., Enum.Parse<T>, Environment.ProcessId, async XML load/save, etc.).

Reviewed changes

Copilot reviewed 67 out of 67 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
test/Utilities/TestFramework.ForTestingMSTest/TestFramework.ForTestingMSTest.csproj	Removes Polyfill package reference.
test/Utilities/Microsoft.Testing.TestInfrastructure/Microsoft.Testing.TestInfrastructure.csproj	Removes Polyfill package reference and Polyfills using.
test/Utilities/Automation.CLI/Automation.CLI.csproj	Removes Polyfill package reference.
test/UnitTests/TestFramework.UnitTests/TestFramework.UnitTests.csproj	Removes Polyfill package reference.
test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.AreEqualTests.cs	Switches to `Split(char)` overload for compatibility.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Microsoft.Testing.Platform.UnitTests.csproj	Removes Polyfill package reference and Polyfills using.
test/UnitTests/Microsoft.Testing.Extensions.VSTestBridge.UnitTests/Microsoft.Testing.Extensions.VSTestBridge.UnitTests.csproj	Removes Polyfill package reference.
test/UnitTests/Microsoft.Testing.Extensions.UnitTests/Microsoft.Testing.Extensions.UnitTests.csproj	Removes Polyfill package reference.
test/UnitTests/MSTestAdapter.UnitTests/MSTestAdapter.UnitTests.csproj	Removes Polyfill package reference.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/ObjectModel/UnitTestElementTests.cs	Replaces `Enum.GetValues<T>()` with non-generic overload for older TFMs.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/MSTestAdapter.PlatformServices.UnitTests.csproj	Removes Polyfill package reference.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/TypeEnumeratorTests.MockedMethodInfoWithExtraAttributes.cs	Removes conditional `using Polyfills;`.
test/UnitTests/MSTest.Analyzers.UnitTests/MSTest.Analyzers.UnitTests.csproj	Removes Polyfill package reference.
test/IntegrationTests/Microsoft.Testing.Platform.Acceptance.IntegrationTests/Microsoft.Testing.Platform.Acceptance.IntegrationTests.csproj	Removes Polyfill package reference.
test/IntegrationTests/MSTest.IntegrationTests/Utilities/TestCaseFilterFactory.cs	Removes `using Polyfills;`.
test/IntegrationTests/MSTest.IntegrationTests/MSTest.IntegrationTests.csproj	Removes Polyfill package reference.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/MSTest.Acceptance.IntegrationTests.csproj	Removes Polyfill package reference.
src/TestFramework/TestFramework/TestFramework.csproj	Removes Polyfill package reference and Polyfills using.
src/TestFramework/TestFramework/Internal/TestDataSourceUtilities.cs	Replaces `string.Join(char, …)` with string separator overload for older TFMs.
src/TestFramework/TestFramework/Internal/PolyfillExtensions.cs	Adds TestFramework-scoped polyfill extensions.
src/TestFramework/TestFramework.Extensions/TestFramework.Extensions.csproj	Removes Polyfill package reference and Polyfills using.
src/Platform/Microsoft.Testing.Platform/Services/ExecutableInfo.cs	Replaces `string.Join(char, …)` usage with string separator overload.
src/Platform/Microsoft.Testing.Platform/ServerMode/JsonRpc/TcpMessageHandler.cs	Adjusts flush logic to avoid `FlushAsync(CancellationToken)` dependency.
src/Platform/Microsoft.Testing.Platform/ServerMode/JsonRpc/ServerModePerCallOutputDevice.cs	Replaces `ConcurrentBag.Clear()` with fallback loop for non-NETCOREAPP.
src/Platform/Microsoft.Testing.Platform/ServerMode/JsonRpc/SerializerUtilities.cs	Replaces `string.Join(char, …)` usage with string separator overload.
src/Platform/Microsoft.Testing.Platform/Microsoft.Testing.Platform.csproj	Removes Polyfill package reference.
src/Platform/Microsoft.Testing.Platform/Helpers/System/SystemFileSystem.cs	Adds polyfilled `File.Move(overwrite)` and async file-read fallback.
src/Platform/Microsoft.Testing.Platform/Helpers/System/SystemEnvironment.cs	Adds `Environment.ProcessId` fallback for older TFMs.
src/Platform/Microsoft.Testing.Platform/Helpers/Sha256Hasher.cs	Adds hashing/hex formatting fallbacks for older TFMs.
src/Platform/Microsoft.Testing.Platform/Helpers/KeyValuePairDeconstruct.cs	Adds Platform-scoped `KeyValuePair` `Deconstruct` polyfill.
src/Platform/Microsoft.Testing.Platform/Builder/TestApplication.cs	Replaces `Enum.Parse<T>` with non-generic overload for older TFMs.
src/Platform/Microsoft.Testing.Platform.MSBuild/Tasks/InvokeTestingPlatformTask.cs	Replaces `Enum.Parse<T>` with non-generic overloads for older TFMs.
src/Platform/Microsoft.Testing.Platform.MSBuild/Microsoft.Testing.Platform.MSBuild.csproj	Removes Polyfill package reference and Polyfills using.
src/Platform/Microsoft.Testing.Platform.AI/Microsoft.Testing.Platform.AI.csproj	Removes Polyfill package reference.
src/Platform/Microsoft.Testing.Extensions.VSTestBridge/Microsoft.Testing.Extensions.VSTestBridge.csproj	Removes Polyfill package reference and Polyfills using.
src/Platform/Microsoft.Testing.Extensions.TrxReport/TrxReportEngine.cs	Adds async XML save fallback for non-NETCOREAPP.
src/Platform/Microsoft.Testing.Extensions.TrxReport/TrxCompareTool.cs	Adds async XML load fallback for non-NETCOREAPP.
src/Platform/Microsoft.Testing.Extensions.TrxReport/Microsoft.Testing.Extensions.TrxReport.csproj	Removes Polyfill package reference and Polyfills using.
src/Platform/Microsoft.Testing.Extensions.TrxReport/Hashing/EmbeddedAttribute.cs	Removes local EmbeddedAttribute in favor of shared polyfills file.
src/Platform/Microsoft.Testing.Extensions.TrxReport.Abstractions/PolyfillExtensions.cs	Adds Abstractions-scoped polyfill extensions (`StringBuilder.AppendJoin`).
src/Platform/Microsoft.Testing.Extensions.TrxReport.Abstractions/Microsoft.Testing.Extensions.TrxReport.Abstractions.csproj	Removes Polyfill package reference and Polyfills using.
src/Platform/Microsoft.Testing.Extensions.TrxReport.Abstractions/GlobalSuppressions.cs	Removes Polyfill-specific suppression entry.
src/Platform/Microsoft.Testing.Extensions.Telemetry/Microsoft.Testing.Extensions.Telemetry.csproj	Removes Polyfill package reference and Polyfills using.
src/Platform/Microsoft.Testing.Extensions.Retry/Microsoft.Testing.Extensions.Retry.csproj	Removes Polyfill package reference.
src/Platform/Microsoft.Testing.Extensions.OpenTelemetry/Microsoft.Testing.Extensions.OpenTelemetry.csproj	Removes Polyfill package reference and Polyfills using.
src/Platform/Microsoft.Testing.Extensions.MSBuild/Microsoft.Testing.Extensions.MSBuild.csproj	Removes Polyfill package reference.
src/Platform/Microsoft.Testing.Extensions.HotReload/Microsoft.Testing.Extensions.HotReload.csproj	Removes Polyfill package reference.
src/Platform/Microsoft.Testing.Extensions.HangDump/Microsoft.Testing.Extensions.HangDump.csproj	Removes Polyfill package reference.
src/Platform/Microsoft.Testing.Extensions.CrashDump/Microsoft.Testing.Extensions.CrashDump.csproj	Removes Polyfill package reference.
src/Platform/Microsoft.Testing.Extensions.AzureFoundry/Microsoft.Testing.Extensions.AzureFoundry.csproj	Removes Polyfill package reference.
src/Platform/Microsoft.Testing.Extensions.AzureDevOpsReport/Microsoft.Testing.Extensions.AzureDevOpsReport.csproj	Removes Polyfill package reference.
src/Analyzers/MSTest.SourceGeneration/Helpers/SystemPolyfills.cs	Removes local type polyfills in favor of shared `eng/Polyfills.cs`.
src/Analyzers/MSTest.Analyzers/RoslynAnalyzerHelpers/AnalyzerPolyfillExtensions.cs	Adds analyzer-scoped polyfill extensions.
src/Analyzers/MSTest.Analyzers/MSTest.Analyzers.csproj	Removes Polyfill package reference.
src/Analyzers/MSTest.Analyzers.CodeFixes/MSTest.Analyzers.CodeFixes.csproj	Removes Polyfill package reference.
src/Adapter/MSTestAdapter.PlatformServices/Utilities/DeploymentUtility.cs	Replaces `Environment.ProcessId` usage with fallback.
src/Adapter/MSTestAdapter.PlatformServices/Services/TestSourceHost.cs	Replaces `string.Join(char, …)` with string separator overload in updated call site.
src/Adapter/MSTestAdapter.PlatformServices/Services/TestDataSource.cs	Replaces `Enum.Parse<T>` with non-generic overload.
src/Adapter/MSTestAdapter.PlatformServices/PolyfillExtensions.cs	Adds adapter-scoped polyfill extensions (including CTS.CancelAsync for < net8).
src/Adapter/MSTestAdapter.PlatformServices/MSTestSettings.cs	Replaces generic Enum APIs with non-generic overloads for older TFMs.
src/Adapter/MSTestAdapter.PlatformServices/MSTestAdapter.PlatformServices.csproj	Removes Polyfill package reference and Polyfills using.
src/Adapter/MSTestAdapter.PlatformServices/Extensions/MethodInfoExtensions.cs	Replaces `Type.IsGenericMethodParameter` usage with portable logic.
src/Adapter/MSTest.TestAdapter/MSTest.TestAdapter.csproj	Removes Polyfill package reference and Polyfills using.
src/Adapter/MSTest.Engine/MSTest.Engine.csproj	Removes Polyfill package reference.
eng/Polyfills.cs	Adds shared repo-wide polyfill implementations and (conditionally) extension polyfills.
Directory.Packages.props	Removes Polyfill package version entry.
Directory.Build.props	Removes Polyfill MSBuild config and adds compilation of `eng/Polyfills.cs`.

src/Adapter/MSTestAdapter.PlatformServices/PolyfillExtensions.cs

src/Platform/Microsoft.Testing.Platform/Helpers/System/SystemEnvironment.cs

src/Adapter/MSTestAdapter.PlatformServices/Utilities/DeploymentUtility.cs

eng/Polyfills.cs

src/Platform/Microsoft.Testing.Platform/ServerMode/JsonRpc/TcpMessageHandler.cs

Copilot

Pull request overview

Copilot reviewed 73 out of 73 changed files in this pull request and generated 1 comment.

src/Platform/Microsoft.Testing.Extensions.TrxReport/TrxReportEngine.cs

…d param - Add Polyfills.Guard, Polyfills.Ensure, and Polyfills.Polyfill backward- compatible types in eng/Polyfills.cs (guarded by IS_CORE_MTP) to prevent TypeLoadException/MissingMethodException when old extension packages reference these types from the platform assembly via InternalsVisibleTo. - Fix unused cancellationToken parameter in TrxReportEngine constructor for netstandard2.0 builds (addresses PR review comment).

Directory.Build.props

eng/Polyfills.cs

Copilot

Pull request overview

Removes the external Polyfill NuGet dependency across the repo and replaces it with an in-repo shared polyfill source file (eng/Polyfills.cs) plus a few project-scoped polyfill extension files, updating call sites to avoid newer BCL APIs on older TFMs.

Changes:

Removed Polyfill PackageReferences (and related Poly* configuration / Using Include="Polyfills" items) from projects and central package management.
Added eng/Polyfills.cs and several project-scoped polyfill extension files to replace previously generated APIs and avoid IVT ambiguity.
Updated code paths to use older-compatible APIs (e.g., enum parsing, file operations, hashing, async XML APIs, TextWriter.FlushAsync(CancellationToken)).

Show a summary per file

File	Description
test/Utilities/TestFramework.ForTestingMSTest/TestFramework.ForTestingMSTest.csproj	Removes Polyfill package reference from test utility project.
test/Utilities/Microsoft.Testing.TestInfrastructure/Microsoft.Testing.TestInfrastructure.csproj	Removes Polyfill package and `Using Polyfills` item.
test/Utilities/Automation.CLI/Automation.CLI.csproj	Removes Polyfill package reference.
test/UnitTests/TestFramework.UnitTests/TestFramework.UnitTests.csproj	Removes Polyfill package reference from unit tests.
test/UnitTests/TestFramework.UnitTests/Assertions/AssertTests.AreEqualTests.cs	Replaces string split call with older-compatible overload usage.
test/UnitTests/MSTestAdapter.UnitTests/MSTestAdapter.UnitTests.csproj	Removes Polyfill package reference.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/ObjectModel/UnitTestElementTests.cs	Replaces generic Enum API usage with non-generic alternative.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/MSTestAdapter.PlatformServices.UnitTests.csproj	Removes Polyfill package reference.
test/UnitTests/MSTestAdapter.PlatformServices.UnitTests/Discovery/TypeEnumeratorTests.MockedMethodInfoWithExtraAttributes.cs	Removes conditional `using Polyfills;`.
test/UnitTests/MSTest.SourceGeneration.UnitTests/TestUtilities/GeneratorTester.cs	Introduces `extern alias` usage to disambiguate referenced analyzer types.
test/UnitTests/MSTest.SourceGeneration.UnitTests/ObjectModels/InlineTestMethodArgumentsInfoTests.cs	Introduces `extern alias` usage for SourceGeneration object model types.
test/UnitTests/MSTest.SourceGeneration.UnitTests/MSTest.SourceGeneration.UnitTests.csproj	Excludes shared polyfills and adds analyzer reference aliasing.
test/UnitTests/MSTest.SourceGeneration.UnitTests/Helpers/ConstantsTests.cs	Uses `extern alias` for SourceGeneration `Constants`.
test/UnitTests/MSTest.SourceGeneration.UnitTests/Generators/TestNodesGeneratorTests.cs	Uses `extern alias` for generator type references.
test/UnitTests/MSTest.Analyzers.UnitTests/MSTest.Analyzers.UnitTests.csproj	Removes Polyfill package reference from analyzer unit tests.
test/UnitTests/Microsoft.Testing.Platform.UnitTests/Microsoft.Testing.Platform.UnitTests.csproj	Removes Polyfill package reference and `Using Polyfills` item.
test/UnitTests/Microsoft.Testing.Extensions.VSTestBridge.UnitTests/Microsoft.Testing.Extensions.VSTestBridge.UnitTests.csproj	Removes Polyfill package reference.
test/UnitTests/Microsoft.Testing.Extensions.UnitTests/Microsoft.Testing.Extensions.UnitTests.csproj	Removes Polyfill package reference.
test/IntegrationTests/MSTest.IntegrationTests/Utilities/TestCaseFilterFactory.cs	Removes `using Polyfills;`.
test/IntegrationTests/MSTest.IntegrationTests/MSTest.IntegrationTests.csproj	Removes Polyfill package reference.
test/IntegrationTests/MSTest.Acceptance.IntegrationTests/MSTest.Acceptance.IntegrationTests.csproj	Removes Polyfill package reference.
test/IntegrationTests/Microsoft.Testing.Platform.Acceptance.IntegrationTests/Microsoft.Testing.Platform.Acceptance.IntegrationTests.csproj	Removes Polyfill package reference.
src/TestFramework/TestFramework/TestFramework.csproj	Removes Polyfill package reference and `Using Polyfills` item.
src/TestFramework/TestFramework/Internal/TestDataSourceUtilities.cs	Replaces `string.Join(char, ...)` with compatible overload.
src/TestFramework/TestFramework/Internal/PolyfillExtensions.cs	Adds TestFramework-scoped polyfill extension methods.
src/TestFramework/TestFramework.Extensions/TestFramework.Extensions.csproj	Removes Polyfill package reference and `Using Polyfills` item.
src/Platform/Microsoft.Testing.Platform/Services/ExecutableInfo.cs	Replaces `string.Join(char, ...)` with compatible overload.
src/Platform/Microsoft.Testing.Platform/ServerMode/JsonRpc/TcpMessageHandler.cs	Adds framework-conditional flush behavior (with/without CancellationToken overload).
src/Platform/Microsoft.Testing.Platform/ServerMode/JsonRpc/ServerModePerCallOutputDevice.cs	Adds framework-conditional `ConcurrentBag.Clear` replacement.
src/Platform/Microsoft.Testing.Platform/ServerMode/JsonRpc/SerializerUtilities.cs	Replaces `string.Join(char, ...)` with compatible overload.
src/Platform/Microsoft.Testing.Platform/Microsoft.Testing.Platform.csproj	Removes Polyfill package reference (core platform now uses source polyfills).
src/Platform/Microsoft.Testing.Platform/Helpers/System/SystemFileSystem.cs	Adds TFM-conditional implementations for `File.Move` overwrite and async read.
src/Platform/Microsoft.Testing.Platform/Helpers/System/SystemEnvironment.cs	Adds fallback `ProcessId` implementation for older TFMs.
src/Platform/Microsoft.Testing.Platform/Helpers/Sha256Hasher.cs	Adds TFM-conditional SHA256 hashing + hex formatting implementations.
src/Platform/Microsoft.Testing.Platform/Helpers/KeyValuePairDeconstruct.cs	Adds platform-scoped KeyValuePair deconstruction polyfill.
src/Platform/Microsoft.Testing.Platform/Builder/TestApplication.cs	Replaces generic Enum.Parse usage with non-generic alternative on older TFMs.
src/Platform/Microsoft.Testing.Platform.MSBuild/Tasks/InvokeTestingPlatformTask.cs	Replaces generic Enum.Parse usage with non-generic alternatives.
src/Platform/Microsoft.Testing.Platform.MSBuild/Microsoft.Testing.Platform.MSBuild.csproj	Removes Polyfill package reference and `Using Polyfills` item.
src/Platform/Microsoft.Testing.Platform.AI/Microsoft.Testing.Platform.AI.csproj	Removes Polyfill package reference.
src/Platform/Microsoft.Testing.Extensions.VSTestBridge/Microsoft.Testing.Extensions.VSTestBridge.csproj	Removes Polyfill package reference and `Using Polyfills` item.
src/Platform/Microsoft.Testing.Extensions.TrxReport/TrxReportEngine.cs	Adds TFM-conditional async XML save handling and cancellation token storage.
src/Platform/Microsoft.Testing.Extensions.TrxReport/TrxCompareTool.cs	Adds TFM-conditional async XML load handling.
src/Platform/Microsoft.Testing.Extensions.TrxReport/Microsoft.Testing.Extensions.TrxReport.csproj	Removes Polyfill package reference and `Using Polyfills` item.
src/Platform/Microsoft.Testing.Extensions.TrxReport/Hashing/EmbeddedAttribute.cs	Removes local EmbeddedAttribute definition (now provided by shared polyfills).
src/Platform/Microsoft.Testing.Extensions.TrxReport.Abstractions/PolyfillExtensions.cs	Adds TrxReport.Abstractions-scoped polyfill extension methods.
src/Platform/Microsoft.Testing.Extensions.TrxReport.Abstractions/Microsoft.Testing.Extensions.TrxReport.Abstractions.csproj	Removes Polyfill package reference and `Using Polyfills` item.
src/Platform/Microsoft.Testing.Extensions.TrxReport.Abstractions/GlobalSuppressions.cs	Removes Polyfill-generated suppression entry.
src/Platform/Microsoft.Testing.Extensions.Telemetry/Microsoft.Testing.Extensions.Telemetry.csproj	Removes Polyfill package reference and `Using Polyfills` item.
src/Platform/Microsoft.Testing.Extensions.Retry/Microsoft.Testing.Extensions.Retry.csproj	Removes Polyfill package reference.
src/Platform/Microsoft.Testing.Extensions.OpenTelemetry/Microsoft.Testing.Extensions.OpenTelemetry.csproj	Removes Polyfill package reference and `Using Polyfills` item.
src/Platform/Microsoft.Testing.Extensions.MSBuild/Microsoft.Testing.Extensions.MSBuild.csproj	Removes Polyfill package reference.
src/Platform/Microsoft.Testing.Extensions.HotReload/Microsoft.Testing.Extensions.HotReload.csproj	Removes Polyfill package reference.
src/Platform/Microsoft.Testing.Extensions.HangDump/Microsoft.Testing.Extensions.HangDump.csproj	Removes Polyfill package reference.
src/Platform/Microsoft.Testing.Extensions.CrashDump/Microsoft.Testing.Extensions.CrashDump.csproj	Removes Polyfill package reference.
src/Platform/Microsoft.Testing.Extensions.AzureFoundry/Microsoft.Testing.Extensions.AzureFoundry.csproj	Removes Polyfill package reference.
src/Platform/Microsoft.Testing.Extensions.AzureDevOpsReport/Microsoft.Testing.Extensions.AzureDevOpsReport.csproj	Removes Polyfill package reference.
src/Analyzers/MSTest.SourceGeneration/Helpers/SystemPolyfills.cs	Removes local polyfill type definitions (now provided by shared polyfills).
src/Analyzers/MSTest.Analyzers/RoslynAnalyzerHelpers/AnalyzerPolyfillExtensions.cs	Adds analyzer-scoped polyfill extension methods.
src/Analyzers/MSTest.Analyzers/MSTest.Analyzers.csproj	Removes Polyfill package reference.
src/Analyzers/MSTest.Analyzers.CodeFixes/MSTest.Analyzers.CodeFixes.csproj	Removes Polyfill package reference.
src/Adapter/MSTestAdapter.PlatformServices/Utilities/DeploymentUtility.cs	Replaces `Environment.ProcessId` usage with older-compatible implementation.
src/Adapter/MSTestAdapter.PlatformServices/Services/TestSourceHost.cs	Replaces `string.Join(char, ...)` with compatible overload.
src/Adapter/MSTestAdapter.PlatformServices/Services/TestDataSource.cs	Replaces generic Enum.Parse usage with non-generic alternative.
src/Adapter/MSTestAdapter.PlatformServices/PolyfillExtensions.cs	Adds adapter-scoped polyfill extension methods (including CancelAsync polyfill).
src/Adapter/MSTestAdapter.PlatformServices/MSTestSettings.cs	Replaces generic Enum APIs with non-generic alternatives for older TFMs.
src/Adapter/MSTestAdapter.PlatformServices/MSTestAdapter.PlatformServices.csproj	Removes Polyfill package reference and `Using Polyfills` item.
src/Adapter/MSTestAdapter.PlatformServices/Extensions/MethodInfoExtensions.cs	Replaces `Type.IsGenericMethodParameter` usage with older-compatible checks.
src/Adapter/MSTestAdapter.PlatformServices/Execution/Polyfills/EmbeddedAttribute.cs	Removes local EmbeddedAttribute definition (now provided by shared polyfills).
src/Adapter/MSTest.TestAdapter/MSTest.TestAdapter.csproj	Removes Polyfill package reference and `Using Polyfills` item.
src/Adapter/MSTest.Engine/MSTest.Engine.csproj	Removes Polyfill package reference.
eng/Polyfills.cs	Adds shared polyfill types/attributes and (for core platform) some extension-method polyfills.
Directory.Packages.props	Removes central `Polyfill` package version entry.
Directory.Build.props	Removes Polyfill configuration properties and globally includes `eng/Polyfills.cs` for C# projects.

Copilot's findings

Comments suppressed due to low confidence (1)

eng/Polyfills.cs:763

The CancelAsync polyfill uses an empty busy-wait loop (while (!...IsCancellationRequested) { }), which can burn CPU on netstandard2.0/net462 for no real benefit (the returned Task.Run(cts.Cancel) already completes after cancellation is requested and callbacks run). Please remove the spin-wait and return the task directly (or use a non-spinning wait strategy).

    public static global::System.Threading.Tasks.Task CancelAsync(this global::System.Threading.CancellationTokenSource cancellationTokenSource)
    {
        if (cancellationTokenSource.IsCancellationRequested)
        {
            return global::System.Threading.Tasks.Task.CompletedTask;
        }

        global::System.Threading.Tasks.Task task = global::System.Threading.Tasks.Task.Run(cancellationTokenSource.Cancel);

        while (!cancellationTokenSource.IsCancellationRequested)
        {
        }

        return task;
    }

Files reviewed: 73/73 changed files
Comments generated: 3

Copilot · 2026-04-09T11:24:55Z

eng/Polyfills.cs

+        public static Index FromStart(int value) => value >= 0 ? new Index(value) : throw new IndexOutOfRangeException(nameof(value));
+
+        public static Index FromEnd(int value) => value >= 0 ? new Index(~value) : throw new IndexOutOfRangeException(nameof(value));


Index.FromStart/Index.FromEnd throw IndexOutOfRangeException for negative inputs, which differs from the BCL behavior (it throws ArgumentOutOfRangeException). To keep the polyfill behavior aligned and avoid surprising exception handling differences, switch these to ArgumentOutOfRangeException (consistent with the Index(int value, ...) ctor above).

Suggested change

public static Index FromStart(int value) => value >= 0 ? new Index(value) : throw new IndexOutOfRangeException(nameof(value));

public static Index FromEnd(int value) => value >= 0 ? new Index(~value) : throw new IndexOutOfRangeException(nameof(value));

public static Index FromStart(int value) => value >= 0 ? new Index(value) : throw new ArgumentOutOfRangeException(nameof(value));

public static Index FromEnd(int value) => value >= 0 ? new Index(~value) : throw new ArgumentOutOfRangeException(nameof(value));

Copilot · 2026-04-09T11:24:56Z

eng/Polyfills.cs

+            throw new global::System.ArgumentNullException(paramName);
+        }
+
+        if (argument.Trim().Length == 0)


Ensure.NotNullOrWhiteSpace uses argument.Trim().Length == 0, which allocates a new string and is less efficient than string.IsNullOrWhiteSpace(argument) (available on all supported TFMs once null is checked). Consider replacing the trim-based check to avoid unnecessary allocations in guard code.

This issue also appears on line 749 of the same file.

Suggested change

if (argument.Trim().Length == 0)

if (global::System.String.IsNullOrWhiteSpace(argument))

Copilot · 2026-04-09T11:24:56Z

src/Adapter/MSTestAdapter.PlatformServices/PolyfillExtensions.cs

+        var task = System.Threading.Tasks.Task.Run(cts.Cancel);
+
+        while (!cts.IsCancellationRequested)
+        {
+        }
+
+        return task;


AdapterCancellationTokenSourcePolyfill.CancelAsync contains a tight busy-wait loop (while (!cts.IsCancellationRequested) { }). This can cause avoidable CPU spikes on .NET Framework. Since you already have Task.Run(cts.Cancel), return that task (or implement a non-spinning completion mechanism) rather than spinning.

Suggested change

var task = System.Threading.Tasks.Task.Run(cts.Cancel);

while (!cts.IsCancellationRequested)

{

}

return task;

return System.Threading.Tasks.Task.Run(cts.Cancel);

Copilot AI review requested due to automatic review settings March 24, 2026 10:32

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Evangelink added 3 commits March 25, 2026 09:36

Fixes

a04524d

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34e635a

Address review comments and fix WaitAsync polyfill timeout behavior

3cc434f

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Remove Polyfill NuGet package dependency#7597

Remove Polyfill NuGet package dependency#7597
Evangelink wants to merge 6 commits intomainfrom
remove-polyfill-dependency

Evangelink commented Mar 24, 2026

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		public static Index FromStart(int value) => value >= 0 ? new Index(value) : throw new IndexOutOfRangeException(nameof(value));

		public static Index FromEnd(int value) => value >= 0 ? new Index(~value) : throw new IndexOutOfRangeException(nameof(value));

	if (argument.Trim().Length == 0)
	if (global::System.String.IsNullOrWhiteSpace(argument))

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Evangelink commented Mar 24, 2026

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