Migrate on-device APK tests from NUnit to MSTest

[jonathanpeppers]

Android framework version

net11.0-android (Preview)

Affected platform version

.NET 11 / MSTest 4.4.0

Description

MSTest 4.4.0 supports NativeAOT: https://www.nuget.org/packages/MSTest/4.4.0

Migrate all on-device APK tests from NUnit to MSTest. This scope includes:

• tests/Mono.Android-Tests/Mono.Android-Tests/Mono.Android.NET-Tests.csproj, including tests loaded from Java.Interop-Tests.NET.csproj
• tests/CodeGen-Binding/Xamarin.Android.JcwGen-Tests/Xamarin.Android.JcwGen-Tests.csproj
• The shared Android instrumentation runner in tests/TestRunner.Core/
• Related CI configuration, test documentation, and package/version configuration

The current shared runner directly uses NUnit APIs for discovery, filtering, execution, result counting, and TRX generation. The migration must preserve:

• Android instrumentation startup and the Microsoft.Android.Run result protocol
• Multiple test assembly support
• Include/exclude category behavior from instrumentation arguments and RuntimeHostConfigurationOption
• Runtime-specific exclusions for Mono, CoreCLR, trimmable type maps, LLVM, and NativeAOT
• Fully-qualified test-name exclusions for external test assemblies
• Execution on the instrumentation/JNI-attached thread where required
• dotnet test, MTP, and TRX reporting behavior

The NativeAOT configuration currently contains NUnit-specific reflection/rooting workarounds (IlcGenerateCompleteTypeMetadata and NativeAOT.rd.xml, including roots for NUnit async adapters). Remove any workarounds that become unnecessary after the migration.

This issue does not include host-side NUnit test projects such as MSBuildDeviceIntegration or the Android SDK/build-task unit tests.

Acceptance criteria

• The two on-device APK test applications and TestRunner.Core no longer reference or use NUnit.
• Existing on-device tests are migrated to MSTest without losing coverage; any intentional semantic differences are documented.
• Existing include/exclude filters and runtime-specific skip behavior continue to work.
• The following CI lanes continue to build, install, run, and publish results:
  • Mono.Android.NET_Tests-Debug
  • Mono.Android.NET_Tests-Release
  • Mono.Android.NET_Tests-NoAab
  • Mono.Android.NET_Tests-Mono
  • Mono.Android.NET_Tests-CoreCLRTrimmable
  • Mono.Android.NET_Tests-NativeAOT
  • Xamarin.Android.JcwGen_Tests
• Local documented dotnet-local build/test commands continue to work and produce TRX results.
• NUnit-specific NativeAOT metadata/rooting workarounds are removed when they are no longer required.

Steps to Reproduce

1. Inspect tests/TestRunner.Core/TestInstrumentation.cs; it uses NUnitTestAssemblyRunner and NUnit filters/results directly.
2. Inspect the two APK test projects; both reference NUnit and use NUnit test attributes/assertions.
3. Build the NativeAOT lane with -p:TestsFlavor=NativeAOT -p:PublishAot=true; the project currently requires NUnit-specific runtime directives.

/cc @Evangelink