Add MSTest reflection source generator (issue #1837) by Evangelink · Pull Request #8586 · microsoft/testfx

Evangelink · 2026-05-25T22:31:11Z

Fixes part of #1837.

What

Introduces a new Roslyn IIncrementalGenerator (project MSTest.SourceGeneration, under src/Analyzers/) that discovers [TestClass] types at compile time and emits a [ModuleInitializer] registering a SourceGeneratedReflectionDataProvider for the user's assembly.

It also adds the runtime infrastructure in MSTestAdapter.PlatformServices (folder SourceGeneration/) to swap the IReflectionOperations and IFileOperations services for source-gen-backed implementations once metadata is registered.

This is the first step toward Native AOT support: when the generator runs, MSTest reads test metadata from compile-time-known data instead of doing reflection at runtime. The feature is opt-in — when no metadata is registered, the platform keeps using the existing reflection-based implementations.

Why

Issue #1837 tracks Native AOT support for MSTest. PR #8263 introduced the IReflectionOperations service abstraction as a prerequisite. This PR delivers the next building block by adding the source generator that will populate that abstraction without reflection.

Layout

Generator (new project): src/Analyzers/MSTest.SourceGeneration/ — ReflectionMetadataGenerator and its emitters/models/helpers, packaged as analyzers/dotnet/cs.
Runtime hook & shims: src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/ — ReflectionMetadataHook, SourceGeneratedReflectionDataProvider, CompositeSourceGeneratedReflectionDataProvider, SourceGeneratedReflectionOperations, SourceGeneratedFileOperations, SourceGeneratorToggle.
Hook surface on PlatformServiceProvider: a single internal SetSourceGeneratedOperations method used by ReflectionMetadataHook to swap providers.
Removed: the legacy src/Adapter/MSTest.Engine/ project and its unit tests, which the new design replaces. (This is what shows up in the solution-file diff.)
Unit tests: test/UnitTests/MSTest.SourceGeneration.UnitTests/.
PublicAPI.Unshipped.txt updated.

Scope (MVP)

Generator emits a per-assembly [ModuleInitializer] that calls ReflectionMetadataHook.SetMetadata.
Composite provider supports multiple test assemblies registering concurrently.
Unit tests cover the happy path ([TestClass] + [TestMethod]), static/abstract classes being skipped, empty-assembly emission, and a Roslyn-compiles-cleanly smoke test.

Known follow-ups (out of scope for this PR)

These are intentionally deferred to keep this PR reviewable:

Populate the rest of the data bag (AssemblyAttributes, TypeAttributes, TypeProperties, TypeMethodAttributes, TypeConstructorsInvoker, TypeMethodLocations). The MVP only emits the assembly name, type list, and per-type method list.
[ModuleInitializer] polyfill for netstandard2.0 / older TFM consumers.
MSBuild gating (opt-in property like EnableMSTestSourceGeneration).
NuGet packaging of the generator into the MSTest analyzer set.
Wire up coverage of DataRow / DynamicData / inherited attributes / base-class roll-up.
AssemblyInitialize / ClassInitialize / TestInitialize lifecycle.

Validation

Built locally with build.cmd -c Debug (0 warnings, 0 errors).

Notes for reviewers

Public API is intentionally minimal: only ReflectionMetadataHook.SetMetadata and the SourceGeneratedReflectionDataProvider shape are public, because the generated module initializer needs to call them.
SourceGeneratorToggle uses Interlocked.Exchange to ensure exactly-once swap and to make the toggle race-free if multiple assemblies' module initializers run.
ReflectionMetadataGenerator skips static and abstract types — they cannot be discovered as test classes.
IReflectionOperations.GetType(string) delegates straight to the fallback so callers cannot bind to a same-named type from the wrong assembly via the composite TypesByName lookup; the assembly-qualified GetType(Assembly, string) overload is the one that uses the source-generated data.
Happy to split this into smaller PRs (e.g., runtime infra first, then generator) if that's easier to review.

Copilot

Pull request overview

This PR introduces an opt-in MSTest reflection metadata source generator (MSTestAdapter.PlatformServices.SourceGeneration) plus new runtime infrastructure in MSTestAdapter.PlatformServices to swap IReflectionOperations/IFileOperations to source-gen-backed implementations via a generated [ModuleInitializer]. This is intended as an early building block toward NativeAOT support (#1837).

Changes:

Add a new incremental generator project that discovers [TestClass]/[TestMethod] and emits a module initializer registering metadata.
Add runtime “source-generated” reflection/file operations and a public hook (ReflectionMetadataHook) for generated code to register metadata.
Add unit tests for the generator and wire new projects into TestFx.slnx and MSTest.slnf, plus update PublicAPI.Unshipped.txt.

Show a summary per file

File	Description
TestFx.slnx	Adds the new generator project + its unit test project to the full solution.
MSTest.slnf	Adds the new generator project + its unit test project to the MSTest solution filter.
src/Adapter/MSTestAdapter.PlatformServices/PlatformServiceProvider.cs	Adds internal hook to swap `IReflectionOperations`/`IFileOperations`.
src/Adapter/MSTestAdapter.PlatformServices/PublicAPI/PublicAPI.Unshipped.txt	Declares new public API surface (`ReflectionMetadataHook`, `SourceGeneratedReflectionDataProvider`).
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/*.cs	Adds runtime hook + source-gen-backed reflection/file operations + toggle.
src/Adapter/MSTestAdapter.PlatformServices.SourceGeneration/*	Adds generator models/helpers + incremental generator + emitter + banned symbols.
test/UnitTests/MSTestAdapter.PlatformServices.SourceGeneration.UnitTests/*	Adds generator unit tests + test runner program + test project.

Copilot's findings

Files reviewed: 19/19 changed files
Comments generated: 14

Evangelink · 2026-05-25T22:47:04Z

🔍 Build Failure Analysis

Summary — The build failed due to a missing interface method and enforced code style violations across multiple target frameworks.

Root cause 1: Missing interface method `SetSourceGeneratedOperations`

The code in ReflectionMetadataHook.cs calls SetSourceGeneratedOperations on an IPlatformServiceProvider interface reference, but this method is not declared in the interface — it only exists as an internal method on the concrete PlatformServiceProvider class (line 181).

Affected files / errors

src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/ReflectionMetadataHook.cs:37 — CS1061: 'IPlatformServiceProvider' does not contain a definition for 'SetSourceGeneratedOperations' (occurs across net8.0 and net9.0 target frameworks)

Proposed fix

Cast PlatformServiceProvider.Instance to the concrete type before calling the internal method:

-        PlatformServiceProvider.Instance.SetSourceGeneratedOperations(reflectionOperations, fileOperations);
+        ((PlatformServiceProvider)PlatformServiceProvider.Instance).SetSourceGeneratedOperations(reflectionOperations, fileOperations);

Alternative fix (if you want to expose this as part of the interface contract):

Add the method to IPlatformServiceProvider.cs:

     ITestContext GetTestContext(ITestMethod? testMethod, string? testClassFullName, IDictionary<string, object?> properties, IMessageLogger messageLogger, UTF.UnitTestOutcome outcome);
+
+    /// <summary>
+    /// Swaps the cached reflection and file operations with source-generated implementations.
+    /// </summary>
+    void SetSourceGeneratedOperations(IReflectionOperations reflectionOperations, IFileOperations fileOperations);
 }

And change the PlatformServiceProvider implementation from internal to public.

Root cause 2: Code style violations (IDE0032 — Use auto property)

Four fields are declared with explicit backing fields but could be converted to auto-properties. The analyzer rule IDE0032 is being enforced as an error.

Affected files / errors

src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratorToggle.cs:13 — error IDE0032: Use auto property
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionOperations.cs:15 — error IDE0032: Use auto property
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedFileOperations.cs:16 — error IDE0032: Use auto property

Proposed fix

Convert explicit backing fields to auto-properties. These are readonly fields that are only assigned once in the constructor, so they can use the newer auto-property syntax with initializers.

Root cause 3: Code style violations (IDE0046 — Simplify conditional expression)

Three locations have if statements that can be simplified to conditional expressions. The analyzer rule IDE0046 is being enforced as an error.

Affected files / errors

src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionOperations.cs:26 — error IDE0046: 'if' statement can be simplified
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionOperations.cs:257 — error IDE0046: 'if' statement can be simplified
src/Adapter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionOperations.cs:291 — error IDE0046: 'if' statement can be simplified

Proposed fix

Simplify if/return patterns to ternary expressions or null-coalescing operators where appropriate.

Build overview

Project: MSTestAdapter.PlatformServices.csproj
Target frameworks: net8.0, net9.0 (errors occur in both)
Configuration: Debug
Exit code: 1 (failure)
Total unique errors: 7 distinct issues (multiplied across TFMs = 14 total occurrences)

The build failed during the CoreCompile target when compiling the newly added SourceGeneration code.

All MSBuild errors (14 occurrences)

Code	Project	File:Line	Message
`CS1061`	`MSTestAdapter.PlatformServices`	`ReflectionMetadataHook.cs:37`	'IPlatformServiceProvider' does not contain a definition for 'SetSourceGeneratedOperations'... (net8.0)
`CS1061`	`MSTestAdapter.PlatformServices`	`ReflectionMetadataHook.cs:37`	'IPlatformServiceProvider' does not contain a definition for 'SetSourceGeneratedOperations'... (net9.0)
`IDE0032`	`MSTestAdapter.PlatformServices`	`SourceGeneratorToggle.cs:13`	Use auto property (net8.0)
`IDE0032`	`MSTestAdapter.PlatformServices`	`SourceGeneratorToggle.cs:13`	Use auto property (net9.0)
`IDE0032`	`MSTestAdapter.PlatformServices`	`SourceGeneratedReflectionOperations.cs:15`	Use auto property (net8.0)
`IDE0032`	`MSTestAdapter.PlatformServices`	`SourceGeneratedReflectionOperations.cs:15`	Use auto property (net9.0)
`IDE0032`	`MSTestAdapter.PlatformServices`	`SourceGeneratedFileOperations.cs:16`	Use auto property (net8.0)
`IDE0032`	`MSTestAdapter.PlatformServices`	`SourceGeneratedFileOperations.cs:16`	Use auto property (net9.0)
`IDE0046`	`MSTestAdapter.PlatformServices`	`SourceGeneratedReflectionOperations.cs:26`	'if' statement can be simplified (net8.0)
`IDE0046`	`MSTestAdapter.PlatformServices`	`SourceGeneratedReflectionOperations.cs:26`	'if' statement can be simplified (net9.0)
`IDE0046`	`MSTestAdapter.PlatformServices`	`SourceGeneratedReflectionOperations.cs:257`	'if' statement can be simplified (net8.0)
`IDE0046`	`MSTestAdapter.PlatformServices`	`SourceGeneratedReflectionOperations.cs:257`	'if' statement can be simplified (net9.0)
`IDE0046`	`MSTestAdapter.PlatformServices`	`SourceGeneratedReflectionOperations.cs:291`	'if' statement can be simplified (net8.0)
`IDE0046`	`MSTestAdapter.PlatformServices`	`SourceGeneratedReflectionOperations.cs:291`	'if' statement can be simplified (net9.0)

_{🤖 Generated by the Build Failure Analysis workflow · commit 6887de2}

Generated by Build Failure Analysis for issue #8586 · ● 1.3M · ◷

Evangelink

Generated by Build Failure Analysis for issue #8586 · ● 1.3M

Consolidates the experimental MSTest.Engine package into the existing MSTest.SourceGeneration package, addresses PR review comments, and adds correctness fixes for ref/out/in parameter signatures, inaccessible nested test classes, file-local test classes, open generic test classes, overridden method deduplication, and composite-provider null handling. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Copilot's findings

Files reviewed: 171/172 changed files
Comments generated: 2

- Delegate IReflectionOperations.GetType(string) to fallback so simple type names cannot bind to a same-named type from the wrong assembly via the composite TypesByName lookup (matches Type.GetType semantics). - Simplify HasByRefParameter to a single LINQ Any() expression. - Drop unused reassignment of GeneratorDriver in the generator test harness's RunGeneratorAndGetCompilation. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Evangelink · 2026-06-01T07:56:08Z

@copilot resolve the merge conflicts in this pull request

…gen-reflection-issue-1837 # Conflicts: # src/Adapter/MSTest.Engine/Engine/TestFrameworkEngine.cs # src/Adapter/MSTest.Engine/PublicAPI/PublicAPI.Unshipped.txt # src/Adapter/MSTest.Engine/TestNodes/InternalUnsafeActionParameterizedTestNode.cs # src/Adapter/MSTest.Engine/TestNodes/InternalUnsafeActionTaskParameterizedTestNode.cs # src/Adapter/MSTest.Engine/TestNodes/InternalUnsafeAsyncActionParameterizedTestNode.cs # src/Adapter/MSTest.Engine/TestNodes/InternalUnsafeAsyncActionTaskParameterizedTestNode.cs # test/UnitTests/MSTest.Engine.UnitTests/BFSTestNodeVisitorTests.cs Co-authored-by: Evangelink <11340282+Evangelink@users.noreply.github.com>

Copilot · 2026-06-01T08:04:34Z

@copilot resolve the merge conflicts in this pull request

Merge conflicts resolved in 8578ce3. All conflicts were "deleted by us" — files in MSTest.Engine that our PR intentionally removed but main had modified. I kept our deletions and also removed the new InternalUnsafeParameterizedTestNodeBase.cs file that main added to the deleted directory. All other changes from main were auto-merged cleanly.

…flection - ReflectionMetadataEmitter: emit [DynamicDependency(All, typeof(T))] per test class on the [ModuleInitializer], so the trimmer keeps constructors and other reflected members alive (otherwise discovery fails with 'Cannot find a valid constructor for test class'). - ReflectionMetadataEmitter: annotate ResolveMethod's Type parameter with [DynamicallyAccessedMembers(PublicMethods | NonPublicMethods)] to satisfy IL2070 in the generated module initializer. - SourceGeneratedReflectionOperations: stop routing fallback through _fallback.GetCustomAttributesCached. ReflectionOperations.NotCachedReflectionAccessor reads PlatformServiceProvider.Instance.ReflectionOperations, which after SetMetadata is the source-gen wrapper itself -- causing infinite mutual recursion and a StackOverflowException at runtime. Use _fallback.GetCustomAttributes (direct reflection) instead. - MSTest.Sdk NativeAOT.targets: add MSTest.TestAdapter package reference and set EnableMSTestRunner/IsTestingPlatformApplication = true (mirroring ClassicEngine.targets) so MSTestAdapter.PlatformServices.dll (the source-generator runtime hook host) is available to NAOT-published apps. - NativeAotTests / SdkTests / TrimTests: tolerate upstream IL warnings from Microsoft.TestPlatform.ObjectModel and System.Private.DataContractSerialization (warnAsError: false) and assert via shared TrimAndAotAssertions.MSTestOwnedSourceFiles that MSTest-owned source files do not appear in publish output, mirroring the pattern established in PR #8686. Rename Publish_ShouldNotProduceTrimWarnings to Publish_WithSourceGeneration_DoesNotSurfaceMSTestOwnedTrimWarnings. - NativeAotTests: use AssertOutputContainsSummary helper (current MTP output format). - samples/NativeAotRunner/TestProject1: convert to MSTest.Sdk shape and drop the pinned MSTest.SourceGeneration 2.0.0-alpha.26228.3 reference (which emitted now- removed Microsoft.Testing.Framework.TestNode types and broke the WindowsSamples CI legs). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Copilot's findings

Files reviewed: 174/175 changed files
Comments generated: 1

A [TestMethod] declared as Test<T>(T value) would have its parameter types collected as ypeof(T), but the generated module initializer is non-generic, so T does not bind there and the compilation fails. Reflection mode handles generic test methods at runtime, so opting into the generator must not turn a valid program into a build error. Add an IsGenericMethod guard alongside the existing open-generic-class and by-ref-parameter guards, and add a unit test covering both the generic-with-params and generic-without-params shapes. Addresses PR review feedback: #8586 (comment) Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…gen-reflection-issue-1837

Copilot

Copilot's findings

Files reviewed: 175/176 changed files
Comments generated: 5

…er non-AOT scenario Unit tests: - Replace the canonical generator test with a full `.Should().Be(expected)` snapshot match so the entire emitted file (header, hint name, namespaces, attributes, module initializer, partial class layout, `TypeMethods`/`Types`/`TypesByName` blocks, `DynamicDependency` attributes) is now verified verbatim instead of relying on a handful of `Contain` checks. - Refactor the overload test to assert against a contiguous block of the generated `TypeMethods` payload rather than separate `Contain` fragments, so reordering or whitespace regressions in the generator are surfaced immediately. - Add tests for: stable hint-name, multiple test classes emitted in source order, test classes declared in the global namespace, methods discovered via a user-defined `TestMethodAttribute` subclass, and `internal` test classes. Extend the by-ref parameter skip test to also cover `ref readonly`. - Add a `NormalizeNewlines` helper so snapshots compare apples-to-apples on Windows (generator emits `\n`; raw string literals in test sources contain `\r\n`). Non-AOT acceptance coverage: - New `SourceGenerationNonAotTests` pins that `MSTest.SourceGeneration` works in a plain SDK project with no `PublishAot`/`PublishTrimmed`. It builds the asset, asserts the generator emitted `<assembly>.MSTestReflectionMetadata.g.cs` via `EmitCompilerGeneratedFiles`, and runs the test host to confirm tests are discovered and executed through the source-generated `ReflectionMetadataHook`. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

… analyzer - Revert sample TestProject1.csproj change - SourceGeneratedFileOperations.LoadAssembly: fall back to inner provider for unregistered assemblies - GetDeclaredMethods/GetRuntimeMethods: always delegate to fallback since TypeMethods is partial - CompositeSourceGeneratedReflectionDataProvider: snapshot pattern with Volatile.Read/Write for thread-safe publishing - Reduce public API to fluent builder: ReflectionMetadataHook.ForAssembly(...).WithTypes(...).WithTestMethods(...).Register() (43 -> 7 entries) - TypeMethodAttributes: key by MethodInfo (was string) now that the type is internal - Update generator to emit fluent-builder calls - Document inherited-[TestClass] limitation in XML docs on ReflectionMetadataHook - Add MSTEST0069 analyzer (InheritedTestClassAttributeWithSourceGeneratorAnalyzer) shipped in MSTest.SourceGeneration package to warn when [TestClass] is only inherited from a base class - Add release tracking files for the new analyzer Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Evangelink · 2026-06-03T16:32:49Z

Pushed e8a3e60 addressing the latest round of review feedback plus the asks about reducing the public-API surface and documenting the inherited-[TestClass] limitation:

Reduced public API (43 -> 7 entries in PublicAPI.Unshipped.txt)

SourceGeneratedReflectionDataProvider (and its nested types) are now internal.
New fluent builder: ReflectionMetadataHook.ForAssembly(assembly).WithTypes(...).WithTestMethods(...).Register().
Source generator updated to emit the new shape.
TypeMethodAttributes re-keyed from string -> MethodInfo (safe now that the type is internal; fixes the overload-ambiguity concern).

Fixes for the runtime contract issues

SourceGeneratedFileOperations.LoadAssembly: falls back to the inner provider for unregistered assemblies (mixed-mode no longer throws).
GetDeclaredMethods / GetRuntimeMethods: always delegate to the fallback provider since the generator only emits [TestMethod]-annotated methods.
CompositeSourceGeneratedReflectionDataProvider: rewritten with an immutable snapshot pattern (Volatile.Read/Volatile.Write publishing of a CompositeState record). Readers can no longer observe a torn intermediate state during Add.
Reverted unrelated change to samples/.../TestProject1.csproj.

Documented + analyzed the inherited-attribute limitation

Added a Discovery limitation section to the XML docs on ReflectionMetadataHook calling out that [TestClass] is only honored when declared directly on the type (inherited [TestClass] is silently skipped by the generator).
New analyzer MSTEST0069 in the MSTest.SourceGeneration package: InheritedTestClassAttributeWithSourceGeneratorAnalyzer. Warns on classes that would only be picked up via attribute inheritance. Shipped only with the source-generation package, so the warning fires only for users who have opted in to source-gen discovery.
Diagnostic ID reserved in DiagnosticIds.cs to avoid future collisions.
Unit tests cover direct attribute, inherited from direct base, inherited from grandparent, abstract base, and subclass-of-TestClassAttribute.

Build + MSTest.SourceGeneration.UnitTests are green locally. Will address the remaining individual conversation threads inline once we agree on the new shape.

Copilot

Copilot's findings

Files reviewed: 181/182 changed files
Comments generated: 1

…gen-reflection-issue-1837 # Conflicts: # src/Analyzers/MSTest.Analyzers/Helpers/DiagnosticIds.cs

…ter method Replaces the fluent MetadataBuilder API (4 public entries) with a single static Register(Assembly, Type[], IReadOnlyDictionary<Type, MethodInfo[]>) method. Defensive copies, TypesByName computation, snapshot creation, and lock-protected publish all happen inline. PublicAPI.Unshipped.txt drops from 7 to 3 lines. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

The MSTest source generator skips static, abstract, open-generic, and file-local classes. Mirror the same filtering in the analyzer to avoid misleading warnings on types that wouldn't become discoverable even after applying [TestClass] directly. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Evangelink · 2026-06-03T21:03:43Z

Update: addressed the open review threads and pushed three commits on top of the rebase to main.

Summary of changes since the original push

e8a3e605a — Initial review-feedback batch: LoadAssembly fallback, GetRuntimeMethods -> _fallback, GetDeclaredMethods always delegates to fallback, CompositeSourceGeneratedReflectionDataProvider rebuilt around an immutable CompositeState snapshot, SourceGeneratedReflectionDataProvider (+ TypeMethodAttributes) made internal, public API reduced from 43 to a small fluent builder, MSTEST0069 analyzer added (InheritedTestClassAttributeWithSourceGenerator) plus tests, NativeAotRunner/TestProject1.csproj revert.
ed5b24a83 — Merge origin/main (one conflict in DiagnosticIds.cs between MSTEST0068 and the MSTEST0069 reservation; both kept).
b16f25f6b — Per the "avoid adding new public APIs on platform services" feedback, collapsed the fluent MetadataBuilder down to a single static ReflectionMetadataHook.Register(Assembly, Type[], IReadOnlyDictionary<Type, MethodInfo[]>). The public surface for this PR is now just 3 lines of PublicAPI.Unshipped.txt (one type, one method, plus #nullable enable).
2959f75ac — Filter open-generic and file-local types from MSTEST0069 so the analyzer mirrors the source generator''s skip rules; added tests for both.

Documented limitation. ReflectionMetadataHook XML docs explicitly call out that the source generator only enumerates types with [TestClass] declared directly on the type (inherited [TestClass] is not picked up). MSTEST0069 flags any class that hits this case.

Full repo build is green (Build succeeded. 0 Warning(s) 0 Error(s)); the MSTest.SourceGeneration.UnitTests suite passes.

…ver)] The single public Register entry point exists only because the source generator's [ModuleInitializer] needs to call across the assembly boundary into MSTestAdapter.PlatformServices. Hand-written code should never use it. Marking the type and method as EditorBrowsable.Never plus strengthening the XML docs makes that intent obvious to anyone browsing the API. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Copilot's findings

Files reviewed: 180/181 changed files
Comments generated: 1

Returning IEnumerator<T> from a struct enumerator goes through an IEnumerable<T> cast and allocates on every foreach. The source-generator pipeline iterates metadata.Classes, cls.Methods, and method.ParameterTypes on every incremental tick, so this was a real allocation hot spot. Return ImmutableArray<T>.Enumerator (a struct) by value so the foreach binds to the duck-typed pattern with no boxing. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

The toggle's UseSourceGenerator getter was never read; Enable() was called once from ReflectionMetadataHook.Register but had no observable effect. The actual provider swap is done in the same code path via PlatformServiceProvider.SetSourceGeneratedOperations. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Copilot's findings

Files reviewed: 179/180 changed files
Comments generated: 2

+    public MethodInfo? GetRuntimeMethod(Type declaringType, string methodName, Type[] parameters, bool includeNonPublic)
+    {
+        foreach (MethodInfo method in GetRuntimeMethods(declaringType))
+        {
+            if (method.Name != methodName)


+            // AssemblyName / Assembly do not make sense for a composite; leave at defaults.
+            var types = new List<Type>();
+            var typesByName = new Dictionary<string, Type>(StringComparer.Ordinal);
+            var typeAttributes = new Dictionary<Type, Attribute[]>();
+            var assemblyAttributes = new List<object>();


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Evangelink force-pushed the dev/amauryleve/sourcegen-reflection-issue-1837 branch from 6887de2 to 73050ee Compare May 28, 2026 16:46

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Comment thread test/UnitTests/MSTest.SourceGeneration.UnitTests/ReflectionMetadataGeneratorTests.cs Fixed

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Comment thread ...apter/MSTestAdapter.PlatformServices/SourceGeneration/SourceGeneratedReflectionOperations.cs Outdated

Comment thread TestFx.slnx

This was referenced May 29, 2026

Convert AOT/trim pragma suppressions to attributes so they propagate to consumers #8686

Merged

Make AOT-incompatible code paths a no-op at runtime in MTP/Native AOT mode #8688

Merged

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Comment thread src/Analyzers/MSTest.SourceGeneration/Generators/ReflectionMetadataGenerator.cs

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Merge remote-tracking branch 'origin/main' into dev/amauryleve/source…

0ec3ecf

…gen-reflection-issue-1837

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Comment thread samples/public/mstest-runner/NativeAotRunner/TestProject1/TestProject1.csproj

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Merge remote-tracking branch 'origin/main' into dev/amauryleve/source…

ed5b24a

…gen-reflection-issue-1837 # Conflicts: # src/Analyzers/MSTest.Analyzers/Helpers/DiagnosticIds.cs

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Evangelink commented May 25, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Evangelink commented May 25, 2026

🔍 Build Failure Analysis

Root cause 1: Missing interface method SetSourceGeneratedOperations

Root cause 2: Code style violations (IDE0032 — Use auto property)

Root cause 3: Code style violations (IDE0046 — Simplify conditional expression)

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Evangelink commented Jun 1, 2026

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Evangelink commented May 25, 2026 •

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Root cause 1: Missing interface method `SetSourceGeneratedOperations`