[mobile] Skip AssemblyLoadContext tests using Assembly.Location on mobile

[github-actions]

Fixes test failures on Android, iOS, tvOS, and MacCatalyst discovered in build #1383320.

Failure

Test: System.Runtime.Loader.Tests.AssemblyLoadContextTest
Helix job: c1e7d30b-9f1d-4f11-9117-cfe78a4df8b9
Work item: System.Runtime.Loader.Tests
Platform: android-arm64 (also affects all mobile platforms)

Failing tests

1. InvalidCastException_DifferentALC_ShowsAssemblyInfo
2. InvalidCastException_GenericTypeArg_DifferentALC_ShowsAssemblyInfo

Root cause

Both tests call LoadFromAssemblyPath(typeof(AssemblyLoadContextTest).Assembly.Location). On mobile platforms, Assembly.Location returns an empty string because assemblies are loaded from the APK/app bundle, not from individual files on disk.

[FAIL] System.Runtime.Loader.Tests.AssemblyLoadContextTest.InvalidCastException_DifferentALC_ShowsAssemblyInfo
System.ArgumentException : Path "" is not an absolute path. (Parameter 'assemblyPath')
   at System.Runtime.Loader.AssemblyLoadContext.LoadFromAssemblyPath(String assemblyPath)
   at System.Runtime.Loader.Tests.AssemblyLoadContextTest.InvalidCastException_DifferentALC_ShowsAssemblyInfo()

Fix

Add nameof(PlatformDetection.IsNotMobile) to both tests' ConditionalFact attributes to skip on mobile platforms where Assembly.Location is not available.

Testing

These tests will be skipped on Android, iOS, tvOS, and MacCatalyst in the runtime-extra-platforms pipeline. Desktop platforms will continue to run the tests.

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Note

This PR was created by GitHub Copilot after analyzing mobile platform CI failures in the runtime-extra-platforms pipeline.

Contributes to #127080

Generated by Mobile Platform Failure Scanner · ● 4.9M · ◷

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[github-actions]

Note

This review was generated by Copilot.

🤖 Copilot Code Review — PR #127082

Holistic Assessment

Motivation: The PR is justified. Both tests call LoadFromAssemblyPath(typeof(AssemblyLoadContextTest).Assembly.Location), and on mobile platforms Assembly.Location returns an empty string because assemblies are bundled in the APK/app bundle. Skipping them on mobile is the correct response.

Approach: The fix works functionally, but uses PlatformDetection.IsNotMobile where the established convention in this same test directory is PlatformDetection.HasAssemblyFiles — a more precise check that directly tests the actual precondition.

Summary: ⚠️ Needs Human Review. The skip is functionally correct and will resolve the mobile failures. However, it diverges from the well-established convention used by 10+ sibling tests in the same directory. A human reviewer should decide whether to accept as-is or align with the existing HasAssemblyFiles pattern.

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Detailed Findings

⚠️ Consistency — IsNotMobile vs established HasAssemblyFiles convention

Flagged by all 3 review models (Claude Opus 4.6, Claude Sonnet 4.5, GPT-5.3-Codex).

The PR adds PlatformDetection.IsNotMobile to guard tests that depend on Assembly.Location being non-empty. However, the same test directory consistently uses PlatformDetection.HasAssemblyFiles for exactly this condition:

File	Line(s)
AssemblyLoadContextTest.cs	111
ContextualReflection.cs	147
LoaderLinkTest.cs	16
RefEmitLoadContextTest.cs	67
SatelliteAssemblies.cs	77, 134, 190, 211

Why HasAssemblyFiles is preferable:

1. Semantically precise: Defined as !string.IsNullOrEmpty(typeof(PlatformDetection).Assembly.Location) — it checks the exact condition these tests depend on.
2. Future-proof: Automatically covers any future platform or configuration (e.g., single-file deployment) where Assembly.Location is empty, without needing manual updates.
3. Less redundant: IsNotMobile excludes Browser/WASI, but IsCoreCLR already excludes those (they don't use CoreCLR). The only net-new exclusions from IsNotMobile are Android and AppleMobile running CoreCLR — which HasAssemblyFiles would also handle.

Suggested change (both test methods at lines 280 and 301):

-[ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsAssemblyLoadingSupported), nameof(PlatformDetection.IsCoreCLR), nameof(PlatformDetection.IsNotMobile))]
+[ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsAssemblyLoadingSupported), nameof(PlatformDetection.IsCoreCLR), nameof(PlatformDetection.HasAssemblyFiles))]

This is advisory, not merge-blocking — the current code is functionally correct.

✅ Correctness — Skip condition prevents the right failures

The change correctly prevents both tests from running on platforms where Assembly.Location returns empty string. The IsNotMobile check does exclude all the right platforms and will resolve the reported CI failures.

Generated by Code Review for issue #127082 · ◷

[Copilot]

Pull request overview

Skips two System.Runtime.Loader tests on mobile platforms where Assembly.Location is empty (assemblies loaded from app bundles/APKs), preventing LoadFromAssemblyPath("") failures in mobile CI.

Changes:

• Add PlatformDetection.IsNotMobile to the ConditionalFact guards for two AssemblyLoadContextTest test cases that rely on Assembly.Location.