Vion.Dale.DevHost.Xunit 0.9.4

Vion.Dale.DevHost.Xunit

xUnit.net v3 integration for Vion Dale DevHost scenario files (RFC 0006). It removes the boilerplate a consumer otherwise hand-rolls to run committed *.scenario.json files as tests:

• [ScenarioFiles] — a theory data source that discovers every committed scenario and yields one (string id, string topology) row per file, display-named by title with spec traits. Each scenario becomes its own entry in Test Explorer / --list-tests.
• DevHostScenarioFixture — a fixture base that loads a topology file, optionally on a deterministic stepping clock, then builds and starts a host. The only thing you supply is your block catalog (ConfigureDi).
• RunScenarioAsync / ApplyScenarioAsync / AssertSucceeded — one-line run + assert over ScenarioRunner.

It is a separate package (not part of Vion.Dale.DevHost) so a non-test DevHost consumer is never forced to take an xUnit dependency.

Usage

// One fixture names your block catalog — the only consumer-specific part of host construction.
public sealed class MyHostFixture : DevHostScenarioFixture
{
    protected override DevHostBuilder ConfigureDi(DevHostBuilder builder) =>
        builder.WithDi<MyLibrary.DependencyInjection>();
}

public class CommittedScenariosShould : IClassFixture<MyHostFixture>
{
    private readonly MyHostFixture _fixture;
    public CommittedScenariosShould(MyHostFixture fixture) => _fixture = fixture;

    [Theory]
    [ScenarioFiles]                       // one row per committed *.scenario.json
    public async Task RunsGreen(string id, string topology)
    {
        await using var host = await _fixture.LoadAsync(topology, stepped: true);
        (await host.RunScenarioAsync(id)).AssertSucceeded();
    }
}

For assertions the JSON scenario vocabulary can't express, use ApplyScenarioAsync as the arrange/stimulate phase and then assert in C#:

[Fact]
public async Task PeakShaving_LeavesConsumerServed()
{
    await using var host = await _fixture.LoadAsync("em-closed-loop", stepped: true);
    await host.ApplyScenarioAsync("peak-shaving");
    // ... arbitrary C# assertions on host.Control.GetProperty(...) ...
}

Determinism

For reproducible, flake-free CI, build the host stepped: true (a FakeTimeProvider virtual clock) and write scenarios using advance / settle / waitUntil rather than the wall-clock wait.

Topologies

A scenario only runs against the topology it declares. [ScenarioFiles] carries each scenario's topology as the second row value so the fixture can build the matching host. Keep a ProjectReference to the library that declares your block types so the topology loader can resolve them.