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. Each extension requires another NuGet package, as described in each section.

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 packaged-app extension registers a full-trust packaged Windows test host from its build-output layout and activates it by Application User Model ID (AUMID). It's the reference consumer of the experimental ITestHostLauncher extension point for packaged Windows apps. This extension requires the Microsoft.Testing.Extensions.PackagedApp NuGet package.

Note

The extension package is available starting with MTP version 2.3.0. Full-trust MSIX registration and AUMID activation are implemented in the microsoft/testfx repository but aren't available in a public NuGet package as of August 6, 2026. The extension is experimental, and its options and output format might change in a future version.

Meet these requirements before you use the extension:

• Target Windows platform version 10.0.19041.0 or later.
• To register an unsigned build-output layout, enable Developer Mode or configure sideloading.
• Use a full-trust packaged desktop host. The extension doesn't support classic UWP, modern .NET UWP with UseUwp, or other AppContainer hosts.

For a complete self-hosted WinUI configuration, see Test WinUI 3 apps with MSTest and MTP.

Manual registration

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

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