How to Test a Windows App Against Experimental WinUI Controls Safely

Windows application developers sometimes need to evaluate new WinUI controls before those controls become part of a stable release. An experimental control may offer a useful interaction pattern, improve accessibility, or simplify a complicated interface. However, using an experimental API also introduces risks that are easy to overlook during development.

A control may change its API, behave differently after a Windows App SDK update, or fail under a particular display configuration. It might also introduce problems with keyboard navigation, accessibility tools, layout measurement, or application startup.

The safest approach is to isolate experimental controls, test them against known scenarios, and keep a working fallback available until the control is suitable for production.

This article explains how to structure a Windows application for experimental WinUI features, write focused UI tests, validate behavior across environments, and prevent an experimental component from destabilizing the rest of the application.

What Are Experimental WinUI Controls?

WinUI is Microsoft's modern native UI framework for Windows applications. It provides controls, layout systems, input handling, styling, and other building blocks for creating Windows interfaces.

Some features may be available only through preview SDKs, experimental packages, or explicitly experimental APIs. Their availability and stability depend on the package, SDK, and feature involved.

An experimental control may have limitations such as:

Its public API may change between releases.
Its layout or interaction behavior may not be fully stabilized.
Accessibility behavior may require additional validation.
Documentation and tooling support may be incomplete.
A future package update may require changes to application code.

Not every new WinUI control is experimental. Before adopting a control, check its actual release status and the documentation for the exact package version used by the application. Do not assume that a control is experimental simply because it is new.

Why Experimental Controls Need Separate Testing

Consider a desktop application that uses an experimental navigation control. During initial development, the control works correctly with a mouse and a standard window size.

Later, a user runs the application at 200% display scaling, navigates with a keyboard, or opens the window at a narrow width. The control may now clip its labels, hide important actions, or behave incorrectly when focus changes.

These problems are not necessarily visible in a basic unit test.

Experimental UI features should therefore be tested at several levels:

Test level	What it validates
Unit tests	Application logic, feature selection, and fallback decisions
XAML and build validation	Resource resolution, bindings, and API compatibility
UI automation	Actual interaction with the rendered control
Accessibility testing	Keyboard behavior, focus order, and accessible names
Environment testing	Behavior across supported Windows and display configurations
Regression testing	Whether existing application features still work

The objective is not simply to confirm that the control appears on the screen. It is to verify that the feature works reliably within the application.

Isolate the Experimental Control Behind a Feature Switch

One of the most useful design decisions is to keep experimental UI code separate from the application's stable interface.

Instead of replacing an existing control throughout the application, introduce a feature switch that determines which implementation is displayed.

For example, a settings page may use a stable navigation control by default and enable an experimental alternative only in a development or test environment.

The feature switch should be controlled by application configuration or a suitable feature-management mechanism. It should not be possible for an ordinary production user to enable an unsupported control accidentally.

Create a Simple Feature Selector

The following C# example illustrates a small configuration-based selector:

public sealed class ExperimentalUiOptions
{
    public bool UseExperimentalNavigation { get; set; }
}

public sealed class NavigationFeatureSelector
{
    private readonly ExperimentalUiOptions _options;

    public NavigationFeatureSelector(
        ExperimentalUiOptions options)
    {
        _options = options;
    }

    public bool UseExperimentalNavigation =>
        _options.UseExperimentalNavigation;
}

This class keeps the decision separate from the UI implementation. It can be tested without creating a window or rendering XAML.

For example:

using Xunit;

public class NavigationFeatureSelectorTests
{
    [Fact]
    public void ExperimentalNavigationIsDisabledByDefault()
    {
        var options = new ExperimentalUiOptions
        {
            UseExperimentalNavigation = false
        };

        var selector = new NavigationFeatureSelector(options);

        Assert.False(selector.UseExperimentalNavigation);
    }

    [Fact]
    public void ExperimentalNavigationCanBeEnabledForTesting()
    {
        var options = new ExperimentalUiOptions
        {
            UseExperimentalNavigation = true
        };

        var selector = new NavigationFeatureSelector(options);

        Assert.True(selector.UseExperimentalNavigation);
    }
}

These tests verify the selection logic, not the behavior of the WinUI control itself. A separate UI test must confirm that the selected implementation renders and works as expected.

For production applications, consider enforcing the feature policy through build configuration or centrally managed settings. A local configuration file should not become an unrestricted way to enable experimental features in a deployed application.

Keep Stable and Experimental XAML Separate

A common mistake is to mix experimental controls into a large XAML page containing unrelated application features.

That makes it harder to isolate rendering errors, compare behavior, and revert the experimental implementation.

Instead, place the experimental control in a dedicated user control and expose only the behavior the rest of the application needs.

For example, the application might have a stable navigation implementation and a separate experimental implementation:

Views/
    Navigation/
        StableNavigationView.xaml
        StableNavigationView.xaml.cs
        ExperimentalNavigationView.xaml
        ExperimentalNavigationView.xaml.cs

The experimental XAML file should reference only APIs supported by the exact SDK and package versions selected for the project. Do not copy markup from a preview sample into a stable application without checking whether the required control and properties are available.

Choose the Implementation at the Page Level

A simplified XAML example can select between two existing implementations:

<Grid>
    <local:StableNavigationView
        x:Name="StableNavigation"
        Visibility="Visible" />

    <local:ExperimentalNavigationView
        x:Name="ExperimentalNavigation"
        Visibility="Collapsed" />
</Grid>

The application can then control visibility using its feature selector.

This example illustrates the isolation pattern rather than a complete production implementation. Both controls exist in the visual tree, so both may initialize or allocate resources. If the experimental control fails during construction, hiding it does not necessarily protect the application.

For controls that may fail during initialization, select and construct the implementation in a way that avoids creating the experimental control when the feature is disabled. A page-level factory or a dedicated host control may be more appropriate.

The key principle is to keep the stable implementation available and avoid making the experimental component a mandatory dependency for the entire application.

Test API Compatibility During the Build

Experimental APIs can change when a project upgrades its Windows App SDK or related packages. Compilation is the first opportunity to catch these changes.

Use a controlled dependency-update process:

Pin the SDK and package versions used by the application.
Test experimental changes on a separate branch.
Restore dependencies from the intended package sources.
Build the application in CI.
Run the relevant unit and UI tests.
Compare the results with the current stable implementation before upgrading the main branch.

A basic Windows CI workflow can compile the application and run its unit tests:

name: Windows UI Build

on:
  pull_request:
    branches:
      - main

permissions:
  contents: read

jobs:
  build:
    runs-on: windows-latest

    steps:
      - name: Check out source
        uses: actions/checkout@v4

      - name: Set up .NET
        uses: actions/setup-dotnet@v4
        with:
          dotnet-version: '10.0.x'

      - name: Restore packages
        run: dotnet restore MyWindowsApp.sln

      - name: Build application
        run: >
          dotnet build MyWindowsApp.sln
          --configuration Release
          --no-restore

Replace the solution name and SDK version with those used by your project. Some WinUI projects require additional Windows SDK components, workloads, or build configuration. The runner must provide the prerequisites needed by the application.

A successful build proves that the current source compiles in that environment. It does not establish that the application can launch, that the control renders correctly, or that it works across the Windows versions supported by your product.

For that reason, build validation should be followed by runtime testing.

Write UI Tests for Real User Interactions

A control can compile successfully and still behave incorrectly. UI automation helps verify how the application behaves after the window has loaded.

For WinUI applications, UI tests may use Microsoft-supported UI automation capabilities, Windows Application Driver where appropriate for the environment, or other compatible automation frameworks. Select tooling based on the application's technology, test infrastructure, and current support status.

Avoid assuming that a particular automation tool supports every WinUI application configuration without additional setup.

Test the Important Interaction Paths

For an experimental navigation control, useful scenarios include:

The control appears when the feature is enabled.
The stable control remains available when the feature is disabled.
Selecting an item opens the correct page.
Keyboard navigation reaches every required action.
Focus moves predictably when a page changes.
The control remains usable when the window is resized.
Errors do not leave the application in an unusable state.

Use stable automation identifiers rather than relying entirely on visible text or element positions.

For example, a XAML element may expose an automation identifier:

<Button
    x:Name="SaveSettingsButton"
    AutomationProperties.AutomationId="SaveSettingsButton"
    Content="Save" />

The exact automation API available to a test depends on the selected framework. The identifier gives the test a stable way to locate the element without depending on its position or localized label.

A UI test should verify the result of an action, not merely that a click was issued. If a user selects a navigation item, assert that the expected page or application state appears afterward.

Test Layout, Scaling, and Window Resizing

Desktop applications run on a variety of monitors and display configurations. A control that works at one window size may fail at another.

Test at minimum and maximum supported window dimensions, common display scaling settings, and the display configurations relevant to your application.

Look for:

Clipped labels or buttons.
Unexpected horizontal scrolling.
Controls overlapping other content.
Text becoming unreadable.
Pop-ups appearing outside the visible window.
Incorrect behavior when the window is resized.
Layout changes after content is loaded asynchronously.

Avoid relying exclusively on screenshot comparisons. Screenshots can reveal visual regressions, but small rendering differences between Windows builds or display configurations can create noisy failures.

Combine visual checks with assertions about element visibility, dimensions, enabled state, and application behavior. Where screenshot comparison is useful, establish an explicit tolerance and maintain baselines for the environments you intend to support.

Validate Keyboard and Accessibility Behavior

Accessibility testing is especially important for controls that introduce new interaction patterns.

A control may look correct with a mouse while remaining difficult to use with a keyboard or screen reader. Experimental controls should not bypass the application's normal accessibility review.

Test the following areas:

Keyboard Navigation

Confirm that users can reach the control and its important actions using the keyboard. Verify the expected Tab order and any arrow-key behavior required by the control's interaction pattern.

Focus should remain visible, and users should not become trapped inside a control unless that behavior is intentional and appropriate.

Accessible Names and Roles

Controls should expose meaningful accessible names and roles. A screen reader should be able to identify the purpose of important actions and communicate relevant state changes.

Avoid relying on decorative icons alone to communicate a command's meaning.

High Contrast and Text Scaling

Check how the control behaves with supported Windows accessibility settings, including high contrast and increased text scaling where relevant.

Do not assume that a control inherits every accessibility behavior correctly simply because it uses the standard WinUI visual system.

If an experimental control fails an essential accessibility requirement, keep the stable implementation active until the issue is resolved.

Handle Runtime Failures Without Hiding Defects

An experimental feature may fail because of an initialization problem, unsupported environment, or unexpected application state.

The application should handle recoverable failures without silently hiding serious defects.

For example, if the experimental control cannot be created, the application might record a diagnostic event and present the stable control instead. However, catching every exception and continuing can conceal a broken application state.

Use a narrow exception-handling boundary around the experimental component, and define which failures permit fallback.

A useful failure policy should specify:

Which initialization failures can trigger fallback.
Which errors must stop the operation.
What diagnostic information is recorded.
Whether the user should see a message.
How the failure is reported to the development team.

Do not log secrets, authentication tokens, or sensitive user data in diagnostic messages.

Test the fallback itself. A fallback that has never been exercised can fail when it is needed most.

Run Tests Across Supported Windows Environments

A test that passes on one developer machine does not guarantee that the feature works across the application's supported environments.

Use a combination of automated and manual testing based on the application's requirements.

Environment	What to verify
Developer workstation	Rapid feedback during implementation
CI build runner	Compilation, package compatibility, and unit tests
Dedicated Windows test machine or VM	Application startup, rendering, and UI automation
Supported Windows versions	Runtime and framework compatibility
Different display configurations	Scaling, resizing, and layout
Accessibility test environment	Keyboard navigation and assistive technology behavior

Not every Windows configuration can be validated using a standard hosted CI runner. Some UI automation tests require an interactive desktop session or specialized infrastructure. Keep build-only tests separate from tests that require a real Windows user session.

Record the Windows version, Windows App SDK version, architecture, and relevant display configuration for failures. This information helps distinguish a product defect from an environment-specific issue.

Common Mistakes to Avoid

Enabling Experimental Controls for Every User

A feature that is still being evaluated should not become the default production experience without a deliberate release decision. Keep the feature disabled by default unless the organization has approved a broader rollout.

Treating Compilation as Runtime Validation

A successful build confirms API compatibility for the selected build environment. It does not prove correct rendering, keyboard behavior, accessibility, or runtime stability.

Testing Only With a Mouse

Keyboard navigation and assistive technologies can reveal interaction defects that ordinary pointer-based tests miss.

Depending on One Windows Version

A control may behave differently across supported Windows environments. Test the configurations that matter to your product instead of assuming one test machine represents every customer.

Catching All Exceptions and Continuing

Broad exception handling can make the application appear resilient while hiding serious failures. Define recoverable conditions explicitly and retain diagnostic evidence.

Removing the Stable Fallback Too Early

Keep the stable implementation until the experimental control has passed the required compatibility, interaction, accessibility, and regression tests.

Advantages and Limitations

Isolating experimental WinUI controls makes it easier to evaluate new functionality without coupling the entire application to an unstable API. Feature switches, automated tests, and a stable fallback can reduce the impact of regressions and make upgrades more manageable.

The approach also introduces maintenance overhead. Supporting two implementations requires additional testing, and experimental controls may need frequent updates as their APIs evolve. UI automation can also be more fragile than unit testing, particularly when tests depend on timing or environment-specific behavior.

These costs are easier to manage when the experimental component has a clearly defined purpose, an explicit acceptance checklist, and a planned decision point for adopting or removing it.

Summary

Testing experimental WinUI controls safely requires more than checking whether the application compiles. Developers need to isolate the control, preserve a stable fallback, validate API compatibility, and test real interactions under supported Windows configurations.

Start with unit tests for feature selection, build validation in CI, and focused UI automation for critical user journeys. Add checks for keyboard navigation, accessibility, resizing, and display scaling. Finally, define how runtime failures are handled and what evidence is required before enabling the feature for production users.

An experimental control should become part of the stable application only when its behavior, compatibility, and failure handling meet the application's requirements. This approach lets teams evaluate new WinUI capabilities while keeping existing Windows applications dependable.