From f4a57784d964e9c6f66f5536606698f1efe4233e Mon Sep 17 00:00:00 2001
From: Georgios Andrianakis <geoand@gmail.com>
Date: Wed, 6 Mar 2024 10:40:50 +0200
Subject: [PATCH] Unwrap processing exception from REST Client when returning a
 Uni

Originally reported at: https://stackoverflow.com/q/78108545/2504224

(cherry picked from commit 3e602388db108a2ba5e64023c147aec552db3cb6)
---
 .../error/ResponseExceptionMapperTest.java     | 18 ++++++++++++++++--
 .../reactive/client/impl/UniInvoker.java       | 10 ++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/extensions/resteasy-reactive/rest-client-reactive/deployment/src/test/java/io/quarkus/rest/client/reactive/error/ResponseExceptionMapperTest.java b/extensions/resteasy-reactive/rest-client-reactive/deployment/src/test/java/io/quarkus/rest/client/reactive/error/ResponseExceptionMapperTest.java
index a676a44fd8b60..578afc39708d2 100644
--- a/extensions/resteasy-reactive/rest-client-reactive/deployment/src/test/java/io/quarkus/rest/client/reactive/error/ResponseExceptionMapperTest.java
+++ b/extensions/resteasy-reactive/rest-client-reactive/deployment/src/test/java/io/quarkus/rest/client/reactive/error/ResponseExceptionMapperTest.java
@@ -19,6 +19,7 @@
 import org.junit.jupiter.api.extension.RegisterExtension;
 
 import io.quarkus.test.QuarkusUnitTest;
+import io.smallrye.mutiny.Uni;
 
 public class ResponseExceptionMapperTest {
     @RegisterExtension
@@ -34,8 +35,11 @@ public class ResponseExceptionMapperTest {
 
     @Test
     void shouldInvokeExceptionMapperOnce() {
-        assertThrows(RuntimeException.class, client::get);
+        assertThrows(TestException.class, client::get);
         assertThat(MyExceptionMapper.executionCount.get()).isEqualTo(1);
+
+        assertThrows(TestException.class, () -> client.uniGet().await().indefinitely());
+        assertThat(MyExceptionMapper.executionCount.get()).isEqualTo(2);
     }
 
     @Path("/error")
@@ -51,6 +55,9 @@ public Response returnError() {
     public interface Client {
         @GET
         String get();
+
+        @GET
+        Uni<String> uniGet();
     }
 
     @Provider
@@ -61,7 +68,14 @@ public static class MyExceptionMapper implements ResponseExceptionMapper<Excepti
         @Override
         public Exception toThrowable(Response response) {
             executionCount.incrementAndGet();
-            return new RuntimeException("My exception");
+            return new TestException("My exception");
+        }
+    }
+
+    public static class TestException extends RuntimeException {
+
+        public TestException(String message) {
+            super(message);
         }
     }
 
diff --git a/independent-projects/resteasy-reactive/client/runtime/src/main/java/org/jboss/resteasy/reactive/client/impl/UniInvoker.java b/independent-projects/resteasy-reactive/client/runtime/src/main/java/org/jboss/resteasy/reactive/client/impl/UniInvoker.java
index dc71c5101ed92..54c6a9f7052a2 100644
--- a/independent-projects/resteasy-reactive/client/runtime/src/main/java/org/jboss/resteasy/reactive/client/impl/UniInvoker.java
+++ b/independent-projects/resteasy-reactive/client/runtime/src/main/java/org/jboss/resteasy/reactive/client/impl/UniInvoker.java
@@ -1,8 +1,10 @@
 package org.jboss.resteasy.reactive.client.impl;
 
 import java.util.concurrent.CompletionStage;
+import java.util.function.Function;
 import java.util.function.Supplier;
 
+import jakarta.ws.rs.ProcessingException;
 import jakarta.ws.rs.client.Entity;
 import jakarta.ws.rs.core.GenericType;
 import jakarta.ws.rs.core.Response;
@@ -25,6 +27,14 @@ public <R> Uni<R> method(String name, Entity<?> entity, GenericType<R> responseT
             public CompletionStage<R> get() {
                 return invoker.method(name, entity, responseType);
             }
+        }).onFailure().transform(new Function<>() {
+            @Override
+            public Throwable apply(Throwable t) {
+                if ((t instanceof ProcessingException) && (t.getCause() != null)) {
+                    return t.getCause();
+                }
+                return t;
+            }
         });
     }