@Test
void emptyPublisherShouldErrorIfSupplierErrored() throws Throwable
{

    RuntimeException error = new RuntimeException( "Error" );
    Publisher<Void> emptyPublisher = createEmptyPublisher( () -> failedFuture( error ) );
    StepVerifier.create( emptyPublisher ).verifyErrorMatches( Predicate.isEqual( error ) );
}