Add test to verify failed unis are not cached

cache/caffeine/src/main/java/io/quarkus/ts/cache/caffeine/ReactiveWithCacheResource.java

@@ -4,6 +4,7 @@
 import jakarta.ws.rs.POST;
 import jakarta.ws.rs.Path;
 import jakarta.ws.rs.PathParam;
+import jakarta.ws.rs.core.Response;
 
 import io.quarkus.cache.CacheInvalidate;
 import io.quarkus.cache.CacheInvalidateAll;
@@ -53,4 +54,23 @@ public Uni<Void> invalidateWithPrefix(@PathParam("prefix") @CacheKey String pref
     public Uni<Void> invalidateAll() {
         return Uni.createFrom().nullItem();
     }
+
+    @GET
+    @Path("/failure/{key}")
+    @CacheResult(cacheName = CACHE_NAME)
+    public Uni<Response> getValueWithFailure(@PathParam("key") @CacheKey String key) {
+
+        int currentCounter = incrementCounter();
+        // Simulate a failure based on the key
+        if (counter == 1) {
+            return Uni.createFrom().failure(new RuntimeException("Simulated failure for key: " + key));
+        } else {
+            return Uni.createFrom().item(Response.ok("Success for key: " + key).build());
+        }
+    }
+
+    private synchronized int incrementCounter() {
+        return counter++;
+    }
+
 }

cache/caffeine/src/test/java/io/quarkus/ts/cache/caffeine/cache/caffeine/CaffeineCacheIT.java

@@ -7,10 +7,13 @@
 import static org.junit.jupiter.api.Assertions.assertNotEquals;
 
 import org.apache.http.HttpStatus;
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
 
 import io.quarkus.test.scenarios.QuarkusScenario;
+import io.restassured.response.Response;
 
 @QuarkusScenario
 public class CaffeineCacheIT {
@@ -72,6 +75,32 @@ public void shouldGetTheSameValueForSamePrefixesWhenGettingValueFromPath(String
                 "Value was equal which means @CacheKey didn't work");
     }
 
+    /**
+     * Ensure that failed unis are not cached
+     */
+    @Tag("QUARKUS-4541")
+    @Test
+    public void shouldNotCacheFailures() {
+        String path = RESOURCE_REACTIVE_API_PATH + "/failure/key-failure";
+
+        // First call to register the failure
+        given()
+                .when().get(path)
+                .then()
+                .statusCode(500);
+
+        // second call should be success
+        Response response = given()
+                .when().get(path)
+                .then()
+                .extract()
+                .response();
+
+        assertNotEquals(500, response.statusCode(), "The failure has been cached and should not be");
+        assertEquals("Success for key: key-failure", response.asString());
+
+    }
+
     /**
      * Check whether the `@CacheInvalidate` annotation does not invalidate all the caches
      */