@Test
public void deleteScalingPolicyIsIdempotent() {

    String jobId = UUID.randomUUID().toString();
    String policyId = UUID.randomUUID().toString();
    AWSApplicationAutoScalingAsync clientAsync = mock(AWSApplicationAutoScalingAsync.class);
    AWSAppScalingConfig config = mock(AWSAppScalingConfig.class);
    AWSAppAutoScalingClient autoScalingClient = new AWSAppAutoScalingClient(clientAsync, config, new NoopRegistry());
    // delete happens successfully on the first attempt
    AtomicBoolean isDeleted = new AtomicBoolean(false);
    when(clientAsync.deleteScalingPolicyAsync(any(), any())).thenAnswer(invocation -> {
        DeleteScalingPolicyRequest request = invocation.getArgument(0);
        AsyncHandler<DeleteScalingPolicyRequest, DeleteScalingPolicyResult> handler = invocation.getArgument(1);
        if (isDeleted.get()) {
            ObjectNotFoundException notFoundException = new ObjectNotFoundException(policyId + " does not exist");
            handler.onError(notFoundException);
            return Future.failed(notFoundException);
        }
        DeleteScalingPolicyResult resultSuccess = new DeleteScalingPolicyResult();
        HttpResponse successResponse = new HttpResponse(null, null);
        successResponse.setStatusCode(200);
        resultSuccess.setSdkHttpMetadata(SdkHttpMetadata.from(successResponse));
        isDeleted.set(true);
        handler.onSuccess(request, resultSuccess);
        return Future.successful(resultSuccess);
    });
    AssertableSubscriber<Void> firstCall = autoScalingClient.deleteScalingPolicy(policyId, jobId).test();
    firstCall.awaitTerminalEvent(2, TimeUnit.SECONDS);
    firstCall.assertNoErrors();
    firstCall.assertCompleted();
    verify(clientAsync, times(1)).deleteScalingPolicyAsync(any(), any());
    // second should complete fast when NotFound and not retry with exponential backoff
    AssertableSubscriber<Void> secondCall = autoScalingClient.deleteScalingPolicy(policyId, jobId).test();
    secondCall.awaitTerminalEvent(2, TimeUnit.SECONDS);
    secondCall.assertNoErrors();
    secondCall.assertCompleted();
    verify(clientAsync, times(2)).deleteScalingPolicyAsync(any(), any());
}