Problem

Commit e5101e573 ("[main] Source code updates from dotnet/dotnet") introduced a regression that silently broke Helix test submission. It made two changes simultaneously:

1. Added Sdk="Microsoft.Build.NoTargets" to UnitTests.proj — This SDK imports its targets at the very end of the project, after the explicit Helix SDK imports. This means Directory.Build.targets → Arcade's Tests.targets defines a Test target last, overriding the Helix SDK's Test target (last definition wins in MSBuild).

2. Refactored the Helix SDK's Microsoft.DotNet.Helix.Sdk.targets — Moved TestDependsOn, BeforeTest, AfterTest, and the Test target definition from inline into NoBuild.targets, which is conditionally skipped when UsingMicrosoftNoTargetsSdk=true.

The result: Arcade's Tests.targets Test target (conditioned on IsUnitTestProject=true, which is false for this project) silently replaced the Helix SDK's Test target. The Test target became a no-op — no Helix jobs were ever submitted. The build reported success with zero tests run.