Context

When setting up test infrastructure for a .NET project that uses Entity Framework Core, MAUI, or other platform-specific frameworks. This skill covers project creation, dependency selection, and test helper patterns.

Patterns

1. Test Project Setup

Create xUnit test project:

bash

dotnet new xunit -n {ProjectName}.Tests -o {ProjectName}.Tests

Match target framework to main project:

•If main project uses net10.0-windows10.0.19041.0, test project must match

•Add platform-specific properties from main .csproj:

xml

<TargetFrameworks>net10.0-windows10.0.19041.0</TargetFrameworks>
<SupportedOSPlatformVersion>10.0.17763.0</SupportedOSPlatformVersion>
<TargetPlatformMinVersion>10.0.17763.0</TargetPlatformMinVersion>

2. Test Dependencies

Standard .NET testing stack:

xml

<PackageReference Include="xunit" Version="2.9.3" />
<PackageReference Include="xunit.runner.visualstudio" Version="3.1.4" />
<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
<PackageReference Include="Moq" Version="4.20.72" />
<PackageReference Include="FluentAssertions" Version="7.0.0" />

For EF Core testing:

xml

<PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="{match-main-version}" />

For HTTP client testing:

xml

<PackageReference Include="RichardSzalay.MockHttp" Version="7.0.0" />

Add global usings:

xml

<ItemGroup>
  <Using Include="Xunit" />
  <Using Include="Moq" />
  <Using Include="FluentAssertions" />
</ItemGroup>

3. Test Directory Structure

Mirror source structure:

code

ProjectName.Tests/
├── Data/                    # Database and EF Core tests
├── Models/                  # Model validation tests
├── Services/
│   ├── Audio/              # Service-specific tests
│   ├── Clipping/
│   └── Transcript/
├── Helpers/                 # Test utilities
└── Fixtures/                # Test data factories

4. Test Helper Patterns

In-Memory Database Factory:

csharp

public static class TestDbContextFactory
{
    public static MyDbContext CreateInMemoryContext()
    {
        var options = new DbContextOptionsBuilder<MyDbContext>()
            .UseInMemoryDatabase(databaseName: Guid.NewGuid().ToString())
            .Options;
        
        var context = new MyDbContext(options);
        context.Database.EnsureCreated();
        return context;
    }
}

Test Data Fixtures:

csharp

public static class TestDataFixtures
{
    public static MyEntity CreateTestEntity(int id = 1)
    {
        return new MyEntity
        {
            Id = id,
            Name = "Test Entity",
            CreatedAt = DateTime.UtcNow
        };
    }
}

5. Test Class Pattern

csharp

public class MyServiceTests : IDisposable
{
    private readonly MyDbContext _context;
    private readonly MyService _service;

    public MyServiceTests()
    {
        _context = TestDbContextFactory.CreateInMemoryContext();
        _service = new MyService(_context);
    }

    [Fact]
    public async Task MethodName_Scenario_ExpectedBehavior()
    {
        // Arrange
        var entity = TestDataFixtures.CreateTestEntity();
        
        // Act
        var result = await _service.ProcessAsync(entity);
        
        // Assert
        result.Should().NotBeNull();
        result.Status.Should().Be(ProcessStatus.Success);
    }

    public void Dispose()
    {
        _context?.Dispose();
    }
}

Examples

Version compatibility check: When adding EF Core InMemory, match the version from main project:

bash

# Check main project version
grep "Microsoft.EntityFrameworkCore" src/MainProject/MainProject.csproj

# Use same version in test project
<PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="10.0.2" />

Running tests:

bash

# Build and run
dotnet test

# With detailed output
dotnet test --verbosity detailed

# Build once, run multiple times
dotnet build
dotnet test --no-build

Anti-Patterns

❌ Don't use different target frameworks between main and test projects ❌ Don't share DbContext instances between tests (use unique database names) ❌ Don't hard-code entity IDs in test fixtures that will conflict ❌ Don't use latest package versions without checking compatibility ❌ Don't forget to dispose of DbContext in test cleanup

✅ Do use Guid.NewGuid() for unique in-memory database names ✅ Do match all framework versions between projects ✅ Do let database assign IDs for entities to avoid tracking conflicts ✅ Do implement IDisposable for proper resource cleanup ✅ Do use FluentAssertions for readable test assertions