Trellis.Testing 3.0.0-alpha.127

Testing Utilities

FluentAssertions extensions, test builders, and fake implementations for testing Railway Oriented Programming patterns with Trellis.

Installation

dotnet add package Trellis.Testing

Quick Start

Result Assertions

using Trellis.Testing;

// Success
result.Should().BeSuccess()
    .Which.Value.Should().Be(expected);

// Failure by type
result.Should().BeFailureOfType<NotFoundError>()
    .Which.Should().HaveDetail("User not found");

Validation Error Assertions

result.Should()
    .BeFailureOfType<ValidationError>()
    .Which.Should()
    .HaveFieldCount(3)
    .And.HaveFieldError("firstName")
    .And.HaveFieldError("email")
    .And.HaveFieldErrorWithDetail("age", "Must be 18 or older");

Maybe Assertions

maybe.Should().HaveValue().Which.Should().Be("hello");
maybe.Should().BeNone();

Test Builders

using Trellis.Testing.Builders;

// Quick Result creation
var result = ResultBuilder.NotFound<User>("User not found");

// Complex validation errors
var error = ValidationErrorBuilder.Create()
    .WithFieldError("email", "Email is required")
    .WithFieldError("age", "Must be 18 or older")
    .Build();

Fake Repository

using Trellis.Testing.Fakes;

var repo = new FakeRepository<User, UserId>();
var sut = new UserService(repo);

var result = await sut.CreateUserAsync(command, CancellationToken.None);

result.Should().BeSuccess();
repo.Exists(result.Value.Id).Should().BeTrue();
repo.PublishedEvents.Should().ContainSingle()
    .Which.Should().BeOfType<UserCreatedEvent>();

TestActorProvider — Scoped Actor Switching

Eliminates try/finally boilerplate in authorization tests. WithActor temporarily switches the actor and restores the previous one on dispose.

using Trellis.Testing.Fakes;

var actorProvider = new TestActorProvider("admin", "Orders.Read", "Orders.Write");

// Temporarily switch to a restricted user
await using var scope = actorProvider.WithActor("user-1", "Orders.Read");
var result = await mediator.Send(new CreateOrderCommand());
result.Should().BeFailure();
// scope disposes → actor reverts to admin

ReplaceResourceLoader — DI Registration Replacement

Replaces existing IResourceLoader<TCommand, TResource> registrations in one call — no manual RemoveAll needed. Registered as scoped, matching the production lifetime.

using Trellis.Testing;

// Stateless fake — capture a pre-created instance
var fakeLoader = new FakeOrderResourceLoader(fakeRepo);
builder.ConfigureServices(services =>
{
    services.ReplaceResourceLoader<CancelOrderCommand, Order>(_ => fakeLoader);
});

// Scoped dependency — resolve from the container
builder.ConfigureServices(services =>
{
    services.ReplaceResourceLoader<CancelOrderCommand, Order>(
        sp => new FakeOrderResourceLoader(sp.GetRequiredService<AppDbContext>()));
});

CreateClientWithActor — Integration Test HttpClient

Creates an HttpClient with the X-Test-Actor header pre-set for authorization integration tests.

using Trellis.Testing;

var client = _factory.CreateClientWithActor("user-1", "Orders.Create", "Orders.Read");
var response = await client.PostAsync("/api/orders", content);

Assertion API Reference

Result

Async variants (BeSuccessAsync, BeFailureAsync, BeFailureOfTypeAsync) are available for Task<Result<T>> and ValueTask<Result<T>>.

Error

ValidationError

Maybe

Before & After

Related Packages

• Trellis.Results — Core Result<T> and Maybe<T> types
• Trellis.DomainDrivenDesign — DDD building blocks
• Trellis.Authorization — Actor, IActorProvider, authorization primitives

License

MIT — see LICENSE for details.