SampleDomainTestt.cs

public class when_updating_a_feature_for_a_product : domain_context<SetFeaturesForProduct, SetFeaturesForProductHandler>
{
    static Product _product;

    Establish context = () =>
    {
        _product = Given<Product>(History.product_created, History.product_feature_added);
        ExpectedEvents = 1;
    };

    Because of = () => When(new SetFeaturesForProduct
    {
        ProductId = _product.EventSourceId,
        Features = new Dictionary<string, object> { {"feature1", "updated feature value"} }
    });

    It should_have_updated_the_feature_value = () => Events.ShouldHave<ProductFeatureUpdated>(
        x => x.Feature == "feature1",
        x => x.Value == "updated feature value");

    It should_do_nothing_else = () => Events.Count().ShouldEqual(ExpectedEvents);
}