i wanna test my “exceptionally”-Block of CompletableFuture.
I’ve already wrote a test, but is fails.

public CompletableFuture<Void> handleRequest(Request request) {
        CompletableFuture<Void> result = null;
        for (MyCustomer entity : request.getData()) {
            result = CompletableFuture.supplyAsync(() -> selectStuff(entity))
                    .thenAccept(completableFutureCaseId ->
                            log.info("Sucess!!!", completableFutureCaseId.resultNow()))
                    .exceptionally(err -> {
                        sendErrorMessage(entity, err);
                        return null;
                    });
        }
        return result;
    } 

Inside of methode ‘selectStuff’ i’am throwing exception. My exceptionally-Block will be executed.
With a debugger, i can see in the beginning of execution of my method, that it jumps directly to “return result” and then it goes further to “supplyAsync”.
My Test looks like:

@Test
void failTostartInsertCase() {

when(myValidator.test(any())).thenReturn(false); //provoke 'throw exception' inside of 'selectStuff' method
CompletableFuture<Void> result = myService.handleRequest(validTestData);
result.join();
assertThat(result.isCompletedExceptionally()).isTrue(); //fails, because its false

}

How could i test it on isCompletedExceptionally=true?