Test host deployment

These extensions control how and where MTP deploys and starts the test host. They use the experimental ITestHostLauncher extension point to control test host deployment and startup.

Tip

When you use Microsoft.Testing.Platform.MSBuild, install an extension's NuGet package to register the extension automatically. MSTest, NUnit, and xUnit runners include Microsoft.Testing.Platform.MSBuild transitively. If you disable the generated entry point, call AddSelfRegisteredExtensions to register the packages that MSBuild contributes.

Packaged app deployment

The Microsoft.Testing.Extensions.PackagedApp extension registers a packaged Windows test host from its build-output layout and activates it by Application User Model ID (AUMID).

The package was introduced in MTP 2.3. Starting with MTP 2.5, it supports packaged full-trust and AppContainer hosts end to end, including:

• Packaged full-trust WinUI 3 apps.
• Modern UWP apps that use UseUwp.
• Classic UWP apps that target uap10.0.
• WinUI 3 packagedClassicApp hosts that set TrustLevel="appContainer".

MSTest.Sdk 4.5 or later configures this extension and the required full-trust app-model sidecar automatically. For application setup and run commands, see Test UWP and WinUI 3 apps with MSTest and MTP.

Caution

Starting with MTP 2.4, Microsoft.Testing.Extensions.PackagedApp follows the MTP release version, and its public registration API is no longer experimental. The generic ITestHostLauncher extension point remains experimental and might change in a future release.

Meet the requirements

Meet these requirements before you use the extension:

• Target Windows platform version 10.0.19041.0 or later for a WinUI 3 packaged app.
• To register an unsigned build-output layout, enable Developer Mode or configure sideloading.
• For UWP, use desktop MSBuild from Visual Studio with the UWP workload and required Windows SDK.
• Run AppContainer test hosts from a non-elevated controller process.

Understand package activation

For a packaged app, the launcher:

1. Locates the AppxManifest.xml that describes the test executable.
2. Registers the build-output layout for the current user.
3. Resolves the selected manifest application's AUMID.
4. Activates the application and connects it to the MTP controller.

For packagedClassicApp and win32App hosts, Windows supplies MTP arguments through the normal process argument array. This behavior also applies to a packagedClassicApp that uses AppContainer.

For a UWP windowsApp, Windows supplies one opaque activation string through LaunchActivatedEventArgs.Arguments. In OnLaunched, call PackagedAppExtensions.GetTestApplicationArguments before you create the MTP builder.

Connect an AppContainer host

An AppContainer token includes a restricted package SID. A named pipe that authorizes only the current user rejects the AppContainer process even when it belongs to the same signed-in user.

In MTP 2.5 or later, the packaged-app launcher derives the selected application's exact package SID and asks MTP to grant that SID the minimum client rights on the controller and extension pipes. The extension doesn't grant ALL APPLICATION PACKAGES, lower the pipe's integrity level, or require a network loopback exemption.

The sidecar transfers controller metadata through package LocalState. It also copies TRX, dump, diagnostic, and retry artifacts from package-owned storage to the requested results directory after the sandboxed host exits.

Control automatic activation

By default, the launcher enables itself only when it finds a package manifest that describes the test application. An unpackaged WinUI 3 app or ordinary console test app stays on the direct-start path.

Use TESTINGPLATFORM_PACKAGEDAPP_LAUNCHER to override package detection:

Value	Behavior
auto or unset	Enable only for a packaged layout.
always	Enable for any layout, including a loose layout that you want to deploy before startup.
never	Disable the packaged-app launcher.

Use TESTINGPLATFORM_PACKAGEDAPP_PIPEAUTHORIZATION to override package-SID authorization:

Value	Behavior
auto or unset	Authorize the package SID only when the manifest declares an AppContainer application.
always	Request package-SID authorization for any packaged layout.
never	Keep the current-user-only pipe authorization.

Register the extension manually

If you don't use automatic MSBuild registration, register the extension in your MTP builder:

var builder = await TestApplication.CreateBuilderAsync(args);
builder.AddPackagedAppDeployment();

Don't call AddPackagedAppDeployment if the application already calls AddSelfRegisteredExtensions and references the package. An MTP run can register only one test host launcher.