aggregateSpecTests

The specification aggregateSpec runs, as a tree of tests for a JUnit @TestFactory: each AggregateSpec.whenCommand, AggregateSpec.advanceTime and AggregateSpec.expectNothingDue is a test of its own, and each AggregateSpec.fork a container of the tests it runs, named by the fork. A failing check fails its own test only: the specification goes on, so the other steps and forks still run and report on their own.

@TestFactory
fun order() = aggregateSpecTests(orderModel) {
    whenCommand(PlaceOrder(...)) {
        expectEventTypes(OrderPlaced::class)
        fork("paid") { whenCommand(PayOrder(...)) { expectEventTypes(OrderPaid::class) } }
        fork("cancelled") { whenCommand(CancelOrder(...)) { expectEventTypes(OrderCancelled::class) } }
    }
}

The specification runs as the tree is built, as 9.x's did; the tests report what each step found. An exception outside a step (a AggregateSpec.given that cannot commit, say) ends its fork, or the specification, and is reported as a failing test Error.