Testing

Chronicle provides lightweight, in-process test utilities that let you verify event appending behavior, read model projections, and reactor side-effects without a running server or database. Tests are fast, isolated, and require no infrastructure.

In Cratis applications, Chronicle tests usually sit inside Cratis Specifications. That makes the event-sourced shape explicit: Establish() or a scenario’s Given builder seeds facts that already happened, Because() appends or provides the event under test, and each [Fact] asserts the new facts, read model state, or side effect.

Packages

<PackageReference Include="Cratis.Specifications.XUnit" />
<PackageReference Include="Cratis.Chronicle.Testing" />

Use Cratis.Testing instead of Cratis.Chronicle.Testing when the same spec also tests Arc commands.

Topics

Guide	Description
Events	Test event appends and constraint behavior in-process using EventScenario
Read Models	Test projections and reducers in-process using ReadModelScenario<TReadModel>
Reactors	Test reactor side-effects in-process using ReactorScenario<TReactor>

A specification-shaped example

public class when_projecting_a_registered_author : Specification
{
    readonly EventSourceId _authorId = EventSourceId.New();
    readonly ReadModelScenario<Author> _scenario = new();

    Task Because() =>
        _scenario.Given
            .ForEventSource(_authorId)
            .Events(new AuthorRegistered("Jane Austen"));

    [Fact] void should_set_the_author_name() =>
        _scenario.Instance!.Name.ShouldEqual("Jane Austen");
}

The projection runs in-process, but the spec still reads like the domain: given the AuthorRegistered fact, the Author read model should contain the name the screen needs.

For the bigger testing model across Specifications, Arc, Chronicle, and full stack slices, see Testing with Cratis.