fork
abstract fun fork(verifyError: Boolean = false, serviceProviderSupplier: (ServiceProvider) -> ServiceProvider = {
require(it is SimpleServiceProvider)
it.copy()
}, commandAggregateFactorySupplier: () -> CommandAggregateFactory = {
SimpleCommandAggregateFactory(InMemoryEventStore())
}, handle: GivenStage<S>.(ExpectedResult<S>) -> Unit): VerifiedStage<S>
为当前环境创建一个完全独立的测试分支上下文