Public indexers are emitted as ordinary test class property metadata #7531

Summary

Public indexers on test classes are included in generated property metadata even though its getter accepts only an instance and no index arguments. This emits an invalid named-property access for closed classes and can make overloaded indexers ambiguous during metadata initialization. Test classes should be able to declare indexers without breaking discovery.

Reproduction

Add a test class to a TUnit test project:

public class IndexerTests
{
    public string this[int index] => index.ToString();
    [Test]
    public void Runs() { }
}

Build the project and inspect the generated property metadata getter. Also cover generic classes with indexers and two overloaded indexers.

Expected and actual

Expected: omit indexers from property metadata, or define deliberate supported behavior that supplies index arguments. Actual: both property enumeration paths select all public IPropertySymbol members without checking IsIndexer, and GetPropertyAccessor emits a named access without arguments. ReflectionInfo also resolves by name (and sometimes return type) without index parameter types.

Source: MetadataGenerationHelper.cs. The same enumeration is present on main as checked on 2026-11-03. This predates #7524 and was identified while dispositioning its non-blocking review.

Environment

Source commit 60669d5; confirmed by source inspection, reproduction not run locally.

Please handle indexers consistently across metadata collection modes and add generator regression coverage.

Acceptance criteria

• Exclude indexers from both generated property-metadata enumeration paths while preserving ordinary public property metadata and its counts.
• Add generator regression snapshots for non-generic classes, generic classes, and overloaded indexers; generated code must compile and metadata initialization must not throw an ambiguous-property exception.
• Verify the regression fixtures discover and execute in both source-generated and reflection modes.

Triage clarification

Confirmed by source inspection on main at ed2b2ab2366c6e7d8eaaf5b0d48307340ebc0140: both enumeration paths still include indexers. #7524 changes generic getter generation but does not filter indexers, so it does not supersede this issue. Reflection discovery's broader missing class-property metadata is tracked separately in #7522; fixing that gap is not a prerequisite for filtering generated indexers here. No reproduction was run during triage.