feat(testing): migrate test infrastructure to Microsoft Testing Platform

.github/workflows/main-build.yaml

@@ -86,7 +86,7 @@ jobs:
         run: dotnet build --no-restore --configuration Release /p:TreatWarningsAsErrors=true
 
       - name: Run tests
-        run: dotnet test --no-build --configuration Release --verbosity normal --collect:"XPlat Code Coverage" --results-directory ./coverage
+        run: dotnet test --no-build --configuration Release --verbosity normal --results-directory ./coverage --coverage --coverage-output-format cobertura
 
       - name: Stop SonarQube
         env:
@@ -99,7 +99,7 @@ jobs:
       - name: Upload coverage reports
         uses: codecov/codecov-action@v5
         with:
-          files: ./coverage/**/coverage.cobertura.xml
+          files: ./coverage/**/*.cobertura.xml
           disable_search: true
           token: ${{ secrets.CODECOV_TOKEN }}
           fail_ci_if_error: true

.github/workflows/pr-build.yaml

@@ -107,7 +107,7 @@ jobs:
         run: dotnet build --no-restore --configuration Release /p:TreatWarningsAsErrors=true
 
       - name: Run tests
-        run: dotnet test --no-build --configuration Release --verbosity normal --collect:"XPlat Code Coverage" --results-directory ./coverage
+        run: dotnet test --no-build --configuration Release --verbosity normal --results-directory ./coverage --coverage --coverage-output-format cobertura
 
       - name: Stop SonarQube
         env:
@@ -120,7 +120,7 @@ jobs:
       - name: Upload coverage reports
         uses: codecov/codecov-action@v5
         with:
-          files: ./coverage/**/coverage.cobertura.xml
+          files: ./coverage/**/*.cobertura.xml
           disable_search: true
           token: ${{ secrets.CODECOV_TOKEN }}
           fail_ci_if_error: true

CLAUDE.md

@@ -82,6 +82,64 @@ internal async Task MyTest(
 - Combine both: use `[AutoNSubstituteData]` with `[Frozen]` to inject configured mocks from a manual
   fixture
 
+# Test Commands
+
+Task wrappers (recommended):
+
+```bash
+task test:all       # dotnet test (Release)
+task test:verbose   # dotnet test (detailed logs)
+task test:coverage  # dotnet test + coverage
+task test:watch     # dotnet watch ... test
+```
+
+Direct `dotnet` commands:
+```bash
+# Run the full test suite (solution-level)
+DOTNET_NOLOGO=1 dotnet test --configuration Release
+
+# Faster inner loop: run a single target framework (projects are multi-targeted)
+DOTNET_NOLOGO=1 dotnet test --configuration Release -f net10.0
+
+# Run a single test project
+DOTNET_NOLOGO=1 dotnet test \
+  --project tests/MinimalLambda.UnitTests/MinimalLambda.UnitTests.csproj \
+  --configuration Release -f net10.0
+
+# Verbose output for debugging
+DOTNET_NOLOGO=1 dotnet test --configuration Release --logger "console;verbosity=detailed"
+```
+
+Run a single test (xUnit v3 + Microsoft.Testing.Platform)
+
+This repo pins the test runner in `global.json`:
+
+```json
+"test": {"runner": "Microsoft.Testing.Platform"}
+```
+
+```bash
+# list tests (copy fully-qualified name)
+DOTNET_NOLOGO=1 dotnet test \
+  --project tests/MinimalLambda.UnitTests/MinimalLambda.UnitTests.csproj \
+  -f net10.0 -v q \
+  --list-tests --no-progress --no-ansi
+
+# run one test method
+DOTNET_NOLOGO=1 dotnet test \
+  --project tests/MinimalLambda.UnitTests/MinimalLambda.UnitTests.csproj \
+  -f net10.0 -v q \
+  --filter-method "MyNamespace.MyTestClass.MyTestMethod" \
+  --minimum-expected-tests 1 \
+  --no-progress --no-ansi
+
+# handy filters
+DOTNET_NOLOGO=1 dotnet test --project tests/MinimalLambda.UnitTests/MinimalLambda.UnitTests.csproj -f net10.0 -v q \
+  --filter-class "MyNamespace.MyTestClass" --minimum-expected-tests 1 --no-progress --no-ansi
+DOTNET_NOLOGO=1 dotnet test --project tests/MinimalLambda.UnitTests/MinimalLambda.UnitTests.csproj -f net10.0 -v q \
+  --filter-namespace "MyNamespace.Tests" --minimum-expected-tests 1 --no-progress --no-ansi
+```
+
 # C# 14 Extension Members - Valid Syntax
 
 ## This is VALID C# 14 syntax - do NOT change it

CONTRIBUTING.md

@@ -293,8 +293,8 @@ dotnet test tests/MinimalLambda.UnitTests
 # Run with verbose output
 dotnet test --verbosity detailed
 
-# Run with coverage (if configured)
-dotnet test /p:CollectCoverage=true
+# Run with coverage (MTP)
+dotnet test --coverage --coverage-output-format cobertura
 ```
 
 ### Test Requirements

Directory.Packages.props

@@ -50,6 +50,7 @@
     <PackageVersion Include="coverlet.collector" Version="6.0.4" />
     <PackageVersion Include="JetBrains.Annotations" Version="2025.2.4" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="18.0.1" />
+    <PackageVersion Include="Microsoft.Testing.Extensions.CodeCoverage" Version="18.0.4" />
     <PackageVersion Include="System.Formats.Asn1" Version="6.0.1" />
     <PackageVersion Include="System.Net.Http" Version="4.3.4" />
     <PackageVersion Include="System.Text.RegularExpressions" Version="4.3.1" />

global.json

@@ -1,6 +1,9 @@
 {
   "sdk": {
     "rollForward": "latestMinor",
-    "version": "10.0.102"
+    "version": "10.0.101"
+  },
+  "test": {
+    "runner": "Microsoft.Testing.Platform"
   }
-}
+}

opencode.json

@@ -0,0 +1,6 @@
+{
+  "$schema": "https://opencode.ai/config.json",
+  "permission": {
+    "git": "ask"
+  }
+}

src/MinimalLambda.Testing/LambdaApplicationFactory.cs

@@ -286,6 +286,13 @@ private void ConfigureHostBuilder(
                 if (string.IsNullOrEmpty(options.BootstrapOptions.RuntimeApiEndpoint))
                     options.BootstrapOptions.RuntimeApiEndpoint = "localhost";
             });
+
+            services.PostConfigure<HostOptions>(options =>
+            {
+                var minShutdownTimeout = TimeSpan.FromSeconds(30);
+                if (options.ShutdownTimeout < minShutdownTimeout)
+                    options.ShutdownTimeout = minShutdownTimeout;
+            });
         });
 
         // Build the host but DON'T start it - server will start it

tasks/TestTasks.yml

@@ -14,23 +14,23 @@ tasks:
     silent: true
     cmds:
       - echo "🧪 Running unit tests"
-      - dotnet test --configuration Release --filter "Category=Unit" --no-build
+      - dotnet test --configuration Release --filter-trait "Category=Unit" --no-build
       - echo "✅ Unit tests completed!"
 
   coverage:
     desc: Run tests with code coverage collection
     silent: true
     cmds:
       - echo "📊 Running tests with coverage collection"
-      - dotnet test --configuration Release --collect:"XPlat Code Coverage" --no-build
+      - dotnet test --configuration Release --coverage --coverage-output-format cobertura --no-build
       - echo "✅ Coverage collection completed!"
 
   watch:
     desc: Run tests in watch mode for TDD
     silent: true
     cmds:
       - echo "👀 Starting test watch mode"
-      - dotnet watch --project tests/MinimalLambda.Tests test --configuration Release
+      - dotnet watch --project tests/MinimalLambda.UnitTests test --configuration Release
 
   verbose:
     desc: Run tests with detailed output for debugging

tests/MinimalLambda.Envelopes.UnitTests/MinimalLambda.Envelopes.UnitTests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>net8.0;net9.0;net10.0</TargetFrameworks>
     <LangVersion>preview</LangVersion>
@@ -17,6 +17,7 @@
     <PackageReference Include="AutoFixture" />
     <PackageReference Include="AwesomeAssertions" />
     <PackageReference Include="coverlet.collector" />
+    <PackageReference Include="Microsoft.Testing.Extensions.CodeCoverage" />
     <PackageReference Include="NSubstitute.Analyzers.CSharp">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

tests/MinimalLambda.OpenTelemetry.UnitTests/MinimalLambda.OpenTelemetry.UnitTests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>net9.0;net10.0</TargetFrameworks>
     <LangVersion>preview</LangVersion>
@@ -26,6 +26,7 @@
     <PackageReference Include="AutoFixture" />
     <PackageReference Include="AwesomeAssertions" />
     <PackageReference Include="coverlet.collector" />
+    <PackageReference Include="Microsoft.Testing.Extensions.CodeCoverage" />
     <PackageReference Include="Microsoft.Extensions.Diagnostics.Testing" />
     <PackageReference Include="NSubstitute.Analyzers.CSharp">
       <PrivateAssets>all</PrivateAssets>

tests/MinimalLambda.SourceGenerators.UnitTests/MinimalLambda.SourceGenerators.UnitTests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>net8.0;net9.0;net10.0</TargetFrameworks>
     <LangVersion>latest</LangVersion>
@@ -18,6 +18,7 @@
     <PackageReference Include="Basic.Reference.Assemblies.Net80" />
     <PackageReference Include="Basic.Reference.Assemblies.Net90" />
     <PackageReference Include="coverlet.collector" />
+    <PackageReference Include="Microsoft.Testing.Extensions.CodeCoverage" />
     <PackageReference Include="JetBrains.Annotations" />
     <PackageReference Include="Microsoft.CodeAnalysis" />
     <PackageReference Include="Microsoft.CodeAnalysis.Common" />

tests/MinimalLambda.Testing.UnitTests/Tests/MinimalLambda.Testing.UnitTests/MinimalLambda.Testing.UnitTests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>net8.0;net9.0;net10.0</TargetFrameworks>
     <ImplicitUsings>enable</ImplicitUsings>
@@ -23,6 +23,7 @@
     <PackageReference Include="AutoFixture" />
     <PackageReference Include="AwesomeAssertions" />
     <PackageReference Include="coverlet.collector" />
+    <PackageReference Include="Microsoft.Testing.Extensions.CodeCoverage" />
     <PackageReference Include="AutoFixture.AutoNSubstitute" />
     <PackageReference Include="NSubstitute.Analyzers.CSharp">
       <PrivateAssets>all</PrivateAssets>

tests/MinimalLambda.UnitTests/MinimalLambda.UnitTests.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>net8.0;net9.0;net10.0</TargetFrameworks>
     <ImplicitUsings>enable</ImplicitUsings>
@@ -33,6 +33,7 @@
     <PackageReference Include="AwesomeAssertions" />
     <PackageReference Include="AutoFixture" />
     <PackageReference Include="coverlet.collector" />
+    <PackageReference Include="Microsoft.Testing.Extensions.CodeCoverage" />
     <PackageReference Include="NSubstitute.Analyzers.CSharp">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>