.NET MAUI Unit Testing with xUnit

Test Project Setup

Create a class library targeting the same TFM as your MAUI app:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFrameworks>net9.0;net10.0</TargetFrameworks>
    <IsPackable>false</IsPackable>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="xunit" Version="2.*" />
    <PackageReference Include="xunit.runner.visualstudio" Version="2.*" />
    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.*" />
    <PackageReference Include="coverlet.collector" Version="6.*" />
    <PackageReference Include="Moq" Version="4.*" />
  </ItemGroup>

  <ItemGroup>
    <ProjectReference Include="..\MyApp\MyApp.csproj" />
  </ItemGroup>
</Project>

Use net9.0 or net10.0 (not a platform-specific TFM like net9.0-ios) so xUnit can run on the desktop test host.

Conditional OutputType for App Projects

If your test project references an app project directly, prevent the app from building as an executable for the test TFM:

<!-- In the MAUI app .csproj -->
<PropertyGroup Condition="'$(TargetFramework)' == 'net9.0'">
  <OutputType>Library</OutputType>
</PropertyGroup>
<PropertyGroup Condition="'$(TargetFramework)' != 'net9.0'">
  <OutputType>Exe</OutputType>
</PropertyGroup>

xUnit Fundamentals

[Fact] — Single Test Case

public class CalculatorTests
{
    [Fact]
    public void Add_TwoNumbers_ReturnsSum()
    {
        // Arrange
        var calculator = new Calculator();

        // Act
        var result = calculator.Add(2, 3);

        // Assert
        Assert.Equal(5, result);
    }
}

[Theory] / [InlineData] — Parameterised Tests

public class ConverterTests
{
    [Theory]
    [InlineData(0, 32)]
    [InlineData(100, 212)]
    [InlineData(-40, -40)]
    public void CelsiusToFahrenheit_ReturnsExpected(double celsius, double expected)
    {
        var result = TemperatureConverter.CelsiusToFahrenheit(celsius);
        Assert.Equal(expected, result, precision: 2);
    }
}

Interface-First Architecture

Define service interfaces so ViewModels can be tested without MAUI platform dependencies:

public interface INavigationService
{
    Task GoToAsync(string route);
    Task GoBackAsync();
}

public interface IDialogService
{
    Task<bool> ConfirmAsync(string title, string message);
}

Register implementations in MauiProgram.cs; inject interfaces into ViewModels.

ViewModel Testing Pattern

public class ItemsViewModelTests
{
    private readonly Mock<IItemService> _itemServiceMock = new();
    private readonly Mock<INavigationService> _navMock = new();

    private ItemsViewModel CreateSut() =>
        new(_itemServiceMock.Object, _navMock.Object);

    [Fact]
    public async Task LoadItems_PopulatesCollection()
    {
        // Arrange
        var items = new List<Item> { new("A"), new("B") };
        _itemServiceMock.Setup(s => s.GetAllAsync()).ReturnsAsync(items);
        var sut = CreateSut();

        // Act
        await sut.LoadItemsCommand.ExecuteAsync(null);

        // Assert
        Assert.Equal(2, sut.Items.Count);
        Assert.False(sut.IsBusy);
    }

    [Fact]
    public async Task SelectItem_NavigatesToDetail()
    {
        // Arrange
        var sut = CreateSut();
        var item = new Item("Test");

        // Act
        await sut.SelectItemCommand.ExecuteAsync(item);

        // Assert
        _navMock.Verify(n => n.GoToAsync($"detail?id={item.Id}"), Times.Once);
    }
}

Mocking Common MAUI Services

Running Tests

# Run all tests
dotnet test

# Run with verbosity
dotnet test --verbosity normal

# Filter by class or method
dotnet test --filter "FullyQualifiedName~ItemsViewModelTests"

# Code coverage with coverlet (outputs to TestResults/)
dotnet test --collect:"XPlat Code Coverage"

# Generate HTML coverage report (requires reportgenerator tool)
dotnet tool install -g dotnet-reportgenerator-globaltool
reportgenerator -reports:TestResults/**/coverage.cobertura.xml \
  -targetdir:TestResults/CoverageReport -reporttypes:Html

On-Device Testing

For tests requiring real platform APIs (sensors, camera, Bluetooth), use the xunit.runner.devices package to run xUnit tests inside a MAUI app on a simulator or physical device. This is separate from dotnet test and runs within the app process.

Tips

• Keep ViewModels free of Application.Current, Shell.Current — wrap in injectable services.
• Use ObservableCollection<T> and [ObservableProperty] (MVVM Toolkit) for testable state.
• Assert on ViewModel properties and CanExecute, not UI bindings.
• Use TaskCompletionSource to test async waiting flows.
• Run dotnet test in CI to catch regressions early.