WebSockets Next: add test that UpgradeRejectedException is thrown

- when WebSocketConnector#connectAndAwait() is called and the upgrade
failed
- added ClientUpgradeFailureTest

extensions/websockets-next/deployment/src/test/java/io/quarkus/websockets/next/test/client/ClientUpgradeFailureTest.java

@@ -0,0 +1,80 @@
+package io.quarkus.websockets.next.test.client;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.net.URI;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import jakarta.inject.Inject;
+import jakarta.inject.Singleton;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+import io.quarkus.test.QuarkusUnitTest;
+import io.quarkus.test.common.http.TestHTTPResource;
+import io.quarkus.websockets.next.HttpUpgradeCheck;
+import io.quarkus.websockets.next.OnOpen;
+import io.quarkus.websockets.next.WebSocket;
+import io.quarkus.websockets.next.WebSocketClient;
+import io.quarkus.websockets.next.WebSocketConnector;
+import io.smallrye.mutiny.Uni;
+import io.vertx.core.http.UpgradeRejectedException;
+
+public class ClientUpgradeFailureTest {
+
+    @RegisterExtension
+    public static final QuarkusUnitTest test = new QuarkusUnitTest()
+            .withApplicationRoot(root -> {
+                root.addClasses(ServerEndpoint.class, ClientEndpoint.class, AlwaysFailing.class);
+            });
+
+    @Inject
+    WebSocketConnector<ClientEndpoint> connector;
+
+    @TestHTTPResource("/")
+    URI uri;
+
+    @Test
+    public void testClient() throws InterruptedException {
+        UpgradeRejectedException e = assertThrows(UpgradeRejectedException.class,
+                () -> connector.baseUri(uri).connectAndAwait());
+        assertEquals(500, e.getStatus());
+        assertTrue(AlwaysFailing.REJECTED.get());
+    }
+
+    @WebSocket(path = "/end")
+    public static class ServerEndpoint {
+
+        @OnOpen
+        String open() {
+            return "Hello!";
+        }
+    }
+
+    @Singleton
+    public static class AlwaysFailing implements HttpUpgradeCheck {
+
+        static final AtomicBoolean REJECTED = new AtomicBoolean();
+
+        @Override
+        public Uni<CheckResult> perform(HttpUpgradeContext context) {
+            REJECTED.set(true);
+            return CheckResult.rejectUpgrade(500);
+        }
+
+    }
+
+    @WebSocketClient(path = "/end")
+    public static class ClientEndpoint {
+
+        @OnOpen
+        String open() {
+            return "Hello!";
+        }
+
+    }
+
+}