Verify.Avalonia

Extends Verify to allow verification of Avalonia UIs.

Getting Started

The test project needs a ModuleInitializer and an Avalonia application with a Style.

[assembly: AvaloniaTestApplication(typeof(VerifyAvaloniaSetupApplication))]

public class VerifyAvaloniaSetupApplication : Application
{
    [ModuleInitializer]
    public static void Init()
    {
        VerifyImageMagick.RegisterComparers(.24);
        VerifierSettings.InitializePlugins();
    }

    public static AppBuilder BuildAvaloniaApp() =>
        AppBuilder
            .Configure<VerifyAvaloniaSetupApplication>()
            .UseSkia()
            .UseHeadless(
                new()
                {
                    UseHeadlessDrawing = false
                });

    public VerifyAvaloniaSetupApplication() =>
        Styles.Add(new FluentTheme());
}

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And add the following NuGet packages:

• https://nuget.org/packages/Verify.Avalonia/
• https://nuget.org/packages/Avalonia.Headless.XUnit/
• https://nuget.org/packages/Avalonia.Themes.Fluent/
• https://nuget.org/packages/Avalonia.Skia/

More details

See Milestones for release notes.

Currently only supported in XUnit since AvaloniaTestAttribute results in incorrect TestContext.Test.MethodName in NUnit

Leverages Avalonia Headless Testing.

See Headless Testing with XUnit and Headless Testing with NUnit for more information.

ModuleInitializer

[ModuleInitializer]
public static void Init()
{
    VerifyImageMagick.RegisterComparers(.097);
    VerifyAvalonia.Initialize();
}

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This sample uses Verify.ImageMagick to ignore small rendering differences that are expected between different operating systems.

Other comparers options:

• https://github.com/VerifyTests/Verify.ImageHash
• https://github.com/VerifyTests/Verify.ImageMagick
• https://github.com/VerifyTests/Verify.Phash
• https://github.com/VerifyTests/Verify.ImageSharp.Compare

Verify.CommunityToolkit.Mvvm

Many Avalonia projects use CommunityToolkit.Mvvm. To ensure proper serialization of MVVM commands, use Verify.CommunityToolkit.Mvvm.

InternalsVisibleTo

Ensure tests projects have InternalsVisibleTo configured in the target app so tests can use generated controls by name.

<ItemGroup>
  <InternalsVisibleTo Include="NUnitTests" />
  <InternalsVisibleTo Include="XUnitTests" />
</ItemGroup>

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Initialize AvaloniaTestApplication

The [AvaloniaTestApplication] attribute wires the tests in the current project with the specific application. It needs to be defined once per project in any file. Verify.Avalonia requires that UseHeadlessDrawing is disabled and .UseSkia() is set.

[assembly: AvaloniaTestApplication(typeof(TestAppBuilder))]

public static class TestAppBuilder
{
    public static AppBuilder BuildAvaloniaApp() =>
        AppBuilder.Configure<App>()
            .UseSkia()
            .UseHeadless(
                new()
                {
                    UseHeadlessDrawing = false
                });
}

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Test

[SuppressMessage("Performance", "CA1822:Mark members as static")]
public class CalculatorTests
{
    [AvaloniaFact]
    public Task Should_Add_Numbers()
    {
        var window = new MainWindow
        {
            DataContext = new MainWindowViewModel()
        };

        window.Show();

        // Set values to the input boxes
        window.FirstOperandInput.Text = "10";
        window.SecondOperandInput.Text = "20";

        // Raise click event on the button:
        window.AddButton.Focus();
        window.KeyPressQwerty(PhysicalKey.Enter, RawInputModifiers.None);

        Assert.Equal("30", window.ResultBox.Text);
        return Verify(window);
    }
}

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Result in the following snapshots

Image

Should_Add_Numbers.verified.verified.png:

Text

{
  Type: MainWindow,
  SizeToContent: WidthAndHeight,
  Title: Simple Calculator,
  CanResize: false,
  Content: {
    Type: StackPanel,
    Spacing: 10.0,
    Width: 280.0,
    Height: 175.0,
    Margin: 10,
    HorizontalAlignment: Left,
    Children: [
      {
        Type: TextBox,
        Text: 10,
        Watermark: Operand 1,
        Name: FirstOperandInput
      },
      {
        Type: TextBox,
        Text: 20,
        Watermark: Operand 2,
        Name: SecondOperandInput
      },
      {
        Type: UniformGrid,
        Columns: 4,
        Children: [
          {
            Type: Button,
            Command: MainWindowViewModel.Add(),
            Content: +,
            Name: AddButton
          },
          {
            Type: Button,
            Command: MainWindowViewModel.Subtract(),
            Content: -,
            Name: SubtractButton
          },
          {
            Type: Button,
            Command: MainWindowViewModel.Multiply(),
            Content: *,
            Name: MultiplyButton
          },
          {
            Type: Button,
            Command: MainWindowViewModel.Divide(),
            Content: /,
            Name: DivideButton
          }
        ]
      },
      {
        Type: StackPanel,
        Spacing: 10.0,
        Orientation: Horizontal,
        Children: [
          {
            Type: TextBlock,
            Text: Result:
          },
          {
            Type: TextBlock,
            Text: 30,
            Name: ResultBox
          }
        ]
      }
    ]
  },
  Background: LightGray,
  Width: 300.0,
  Height: 195.0,
  IsVisible: true,
  DataContext: {
    FirstOperand: 10.0,
    SecondOperand: 20.0,
    Result: 30,
    AddCommand: MainWindowViewModel.Add(),
    SubtractCommand: MainWindowViewModel.Subtract(),
    MultiplyCommand: MainWindowViewModel.Multiply(),
    DivideCommand: MainWindowViewModel.Divide()
  }
}

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