ADR 0002 — TUnit on Microsoft.Testing.Platform

Status: accepted (2026-08)

Decision

All tests use TUnit running in Microsoft.Testing.Platform (MTP) mode of dotnet test (opted in via the test.runner setting in global.json; requires .NET 10 SDK).

Context

TUnit is source-generator-based and Native AOT-compatible — the same ethos as Emissary itself (no reflection, compile-time wiring). MTP is the modern test runner; VSTest mode is legacy for MTP projects on the .NET 10 SDK.

Consequences

• Test projects are executables (OutputType=Exe).
• Coverage is collected by Microsoft.Testing.Extensions.CodeCoverage (--coverage platform option), not coverlet.
• Stryker.NET cannot run MTP test projects yet (stryker-mutator/stryker-net#3094) — see ADR 0003.