README.md

Recommended Markdown Viewer: Markdown Editor

Getting Started

Get started with unit testing, Use the MSTest framework in unit tests, and Run unit tests with Test Explorer provide an overview of the MSTest framework and Test Explorer.

Testing UI Controls

Unit tests that exercise UI controls must run on the WinUI UI thread or they will throw an exception. To run a test on the WinUI UI thread, mark the test method with [UITestMethod] instead of [TestMethod]. During test execution, the test host will launch Dev Home and dispatch the test to Dev Home's UI thread.

The below example creates a new Grid() and then validates that its ActualWidth is 0.

[UITestMethod]
public void UITestMethod()
{
    Assert.AreEqual(0, new Grid().ActualWidth);
}

Dependency Injection and Mocking

Template Studio uses dependency injection which means class dependencies implement interfaces and those dependencies are injected via class constructors.

One of the many benefits of this approach is improved testability, since tests can produce mock implementations of the interfaces and pass them into the object being tested, isolating the object being tested from its dependencies. To mock an interface, create a class that implements the interface, create stub implementations of the interface members, then pass an instance of the class into the object constructor.

The below example demonstrates testing the ViewModel for the Settings page. SettingsViewModel depends on IThemeSelectorService, so a MockThemeSelectorService class is introduced that implements the interface with stub implementations, and then an instance of that class is passed into the SettingsViewModel constructor. The VerifyVersionDescription test then validates that the VersionDescription property of the SettingsViewModel returns the expected value.

// SettingsViewModelTests.cs

[TestClass]
public class SettingsViewModelTests
{
    private readonly SettingsViewModel _viewModel;

    public SettingsViewModelTests()
    {
        _viewModel = new SettingsViewModel(new MockThemeSelectorService());
    }

    [TestMethod]
    public void VerifyVersionDescription()
    {
        Assert.IsTrue(Regex.IsMatch(_viewModel.VersionDescription, @"App1 - \d\.\d\.\d\.\d"));
    }
}

// Mocks/MockThemeSelectorService.cs

internal class MockThemeSelectorService : IThemeSelectorService
{
    public ElementTheme Theme => ElementTheme.Default;

    public Task InitializeAsync() => Task.CompletedTask;

    public Task SetRequestedThemeAsync() => Task.CompletedTask;

    public Task SetThemeAsync(ElementTheme theme) => Task.CompletedTask;
}

CI Pipelines

See README.md for guidance on building and testing projects in CI pipelines.