Mode d’emploi
- Copiez la commande et examinez le paquet avant de l’installer dans votre environnement agent.
- Consultez le document original pour les outils, identifiants et environnements requis.
- Décrivez les entrées et le livrable souhaité ; comparez la sortie aux sources.
npx skills add https://github.com/affaan-m/ecc --skill csharp-testingAvant de commencer
- L’installation n’inclut ni abonnement au modèle, ni quota API, ni accès aux fichiers.
- Étoiles et installations reflètent l’activité, pas un test indépendant de qualité ou de sécurité.
Document Skill original
Rendu depuis le dépôt source en conservant titres, exemples, code, tableaux, liens et images.
C# Testing Patterns
Comprehensive testing patterns for .NET applications using xUnit, FluentAssertions, and modern testing practices.
When to Activate
- Writing new tests for C# code
- Reviewing test quality and coverage
- Setting up test infrastructure for .NET projects
- Debugging flaky or slow tests
Test Framework Stack
| Tool | Purpose |
|---|---|
| xUnit | Test framework (preferred for .NET) |
| FluentAssertions | Readable assertion syntax |
| NSubstitute or Moq | Mocking dependencies |
| Testcontainers | Real infrastructure in integration tests |
| WebApplicationFactory | ASP.NET Core integration tests |
| Bogus | Realistic test data generation |
Unit Test Structure
Arrange-Act-Assert
csharp
public sealed class OrderServiceTests
{
private readonly IOrderRepository _repository = Substitute.For<IOrderRepository>();
private readonly ILogger<OrderService> _logger = Substitute.For<ILogger<OrderService>>();
private readonly OrderService _sut;
public OrderServiceTests()
{
_sut = new OrderService(_repository, _logger);
}
[Fact]
public async Task PlaceOrderAsync_ReturnsSuccess_WhenRequestIsValid()
{
// Arrange
var request = new CreateOrderRequest
{
CustomerId = "cust-123",
Items = [new OrderItem("SKU-001", 2, 29.99m)]
};
// Act
var result = await _sut.PlaceOrderAsync(request, CancellationToken.None);
// Assert
result.IsSuccess.Should().BeTrue();
result.Value.Should().NotBeNull();
result.Value!.CustomerId.Should().Be("cust-123");
}
[Fact]
public async Task PlaceOrderAsync_ReturnsFailure_WhenNoItems()
{
// Arrange
var request = new CreateOrderRequest
{
CustomerId = "cust-123",
Items = []
};
// Act
var result = await _sut.PlaceOrderAsync(request, CancellationToken.None);
// Assert
result.IsSuccess.Should().BeFalse();
result.Error.Should().Contain("at least one item");
}
}Parameterized Tests with Theory
csharp
[Theory]
[InlineData("", false)]
[InlineData("a", false)]
[InlineData("ab@c.d", false)]
[InlineData("user@example.com", true)]
[InlineData("user+tag@example.co.uk", true)]
public void IsValidEmail_ReturnsExpected(string email, bool expected)
{
EmailValidator.IsValid(email).Should().Be(expected);
}
[Theory]
[MemberData(nameof(InvalidOrderCases))]
public async Task PlaceOrderAsync_RejectsInvalidOrders(CreateOrderRequest request, string expectedError)
{
var result = await _sut.PlaceOrderAsync(request, CancellationToken.None);
result.IsSuccess.Should().BeFalse();
result.Error.Should().Contain(expectedError);
}
public static TheoryData<CreateOrderRequest, string> InvalidOrderCases => new()
{
{ new() { CustomerId = "", Items = [ValidItem()] }, "CustomerId" },
{ new() { CustomerId = "c1", Items = [] }, "at least one item" },
{ new() { CustomerId = "c1", Items = [new("", 1, 10m)] }, "SKU" },
};Mocking with NSubstitute
csharp
[Fact]
public async Task GetOrderAsync_ReturnsNull_WhenNotFound()
{
// Arrange
var orderId = Guid.NewGuid();
_repository.FindByIdAsync(orderId, Arg.Any<CancellationToken>())
.Returns((Order?)null);
// Act
var result = await _sut.GetOrderAsync(orderId, CancellationToken.None);
// Assert
result.Should().BeNull();
}
[Fact]
public async Task PlaceOrderAsync_PersistsOrder()
{
// Arrange
var request = ValidOrderRequest();
// Act
await _sut.PlaceOrderAsync(request, CancellationToken.None);
// Assert — verify the repository was called
await _repository.Received(1).AddAsync(
Arg.Is<Order>(o => o.CustomerId == request.CustomerId),
Arg.Any<CancellationToken>());
}ASP.NET Core Integration Tests
WebApplicationFactory Setup
csharp
public sealed class OrderApiTests : IClassFixture<WebApplicationFactory<Program>>
{
private readonly HttpClient _client;
public OrderApiTests(WebApplicationFactory<Program> factory)
{
_client = factory.WithWebHostBuilder(builder =>
{
builder.ConfigureServices(services =>
{
// Replace real DB with in-memory for tests
services.RemoveAll<DbContextOptions<AppDbContext>>();
services.AddDbContext<AppDbContext>(options =>
options.UseInMemoryDatabase("TestDb"));
});
}).CreateClient();
}
[Fact]
public async Task GetOrder_Returns404_WhenNotFound()
{
var response = await _client.GetAsync($"/api/orders/{Guid.NewGuid()}");
response.StatusCode.Should().Be(HttpStatusCode.NotFound);
}
[Fact]
public async Task CreateOrder_Returns201_WithValidRequest()
{
var request = new CreateOrderRequest
{
CustomerId = "cust-1",
Items = [new("SKU-001", 1, 19.99m)]
};
var response = await _client.PostAsJsonAsync("/api/orders", request);
response.StatusCode.Should().Be(HttpStatusCode.Created);
response.Headers.Location.Should().NotBeNull();
}
}Testing with Testcontainers
csharp
public sealed class PostgresOrderRepositoryTests : IAsyncLifetime
{
private readonly PostgreSqlContainer _postgres = new PostgreSqlBuilder()
.WithImage("postgres:16-alpine")
.Build();
private AppDbContext _db = null!;
public async Task InitializeAsync()
{
await _postgres.StartAsync();
var options = new DbContextOptionsBuilder<AppDbContext>()
.UseNpgsql(_postgres.GetConnectionString())
.Options;
_db = new AppDbContext(options);
await _db.Database.MigrateAsync();
}
public async Task DisposeAsync()
{
await _db.DisposeAsync();
await _postgres.DisposeAsync();
}
[Fact]
public async Task AddAsync_PersistsOrder()
{
var repo = new SqlOrderRepository(_db);
var order = Order.Create("cust-1", [new OrderItem("SKU-001", 2, 10m)]);
await repo.AddAsync(order, CancellationToken.None);
var found = await repo.FindByIdAsync(order.Id, CancellationToken.None);
found.Should().NotBeNull();
found!.Items.Should().HaveCount(1);
}
}Test Organization
tests/
MyApp.UnitTests/
Services/
OrderServiceTests.cs
PaymentServiceTests.cs
Validators/
EmailValidatorTests.cs
MyApp.IntegrationTests/
Api/
OrderApiTests.cs
Repositories/
OrderRepositoryTests.cs
MyApp.TestHelpers/
Builders/
OrderBuilder.cs
Fixtures/
DatabaseFixture.csTest Data Builders
csharp
public sealed class OrderBuilder
{
private string _customerId = "cust-default";
private readonly List<OrderItem> _items = [new("SKU-001", 1, 10m)];
public OrderBuilder WithCustomer(string customerId)
{
_customerId = customerId;
return this;
}
public OrderBuilder WithItem(string sku, int quantity, decimal price)
{
_items.Add(new OrderItem(sku, quantity, price));
return this;
}
public Order Build() => Order.Create(_customerId, _items);
}
// Usage in tests
var order = new OrderBuilder()
.WithCustomer("cust-vip")
.WithItem("SKU-PREMIUM", 3, 99.99m)
.Build();Common Anti-Patterns
| Anti-Pattern | Fix |
|---|---|
| Testing implementation details | Test behavior and outcomes |
| Shared mutable test state | Fresh instance per test (xUnit does this via constructors) |
Thread.Sleep in async tests | Use Task.Delay with timeout, or polling helpers |
Asserting on ToString() output | Assert on typed properties |
| One giant assertion per test | One logical assertion per test |
| Test names describing implementation | Name by behavior: Method_ExpectedResult_WhenCondition |
Ignoring CancellationToken | Always pass and verify cancellation |
Running Tests
bash
# Run all tests
dotnet test
# Run with coverage
dotnet test --collect:"XPlat Code Coverage"
# Run specific project
dotnet test tests/MyApp.UnitTests/
# Filter by test name
dotnet test --filter "FullyQualifiedName~OrderService"
# Watch mode during development
dotnet watch test --project tests/MyApp.UnitTests/