Quarkus tests: a random port instead of the fixed 8081

Parallel builds collided on Quarkus's default test port. The deployment
tests run with quarkus.http.test-port=0; the integration tests take a free
port from a global test resource, since the client bean's URI is resolved
before a random port is bound.

Author: Mark Pollack

CHANGELOG.md

@@ -1663,6 +1663,13 @@ Found by measuring coverage with JaCoCo; each has a test.
 
 ### Build
 
+- **The Quarkus tests no longer bind the fixed port 8081.** Quarkus serves `@QuarkusTest` and
+  `QuarkusUnitTest` applications on `quarkus.http.test-port`, 8081 by default, so two builds on one
+  machine (or anything else on 8081) failed with "Port already bound: 8081". The deployment
+  module's tests now run with `quarkus.http.test-port=0`, a random port, and the integration tests
+  on a free port a test resource picks (the client bean's URI is read at startup, before a random
+  port is known). The tests read the bound port through `@TestHTTPResource`.
+
 - **Spring Boot's configuration metadata is written on JDK 21 and later too.** The `errorprone`
   profile (JDK 21+) sets the compiler's processor path to Error Prone and NullAway, which turns off
   discovering processors on the classpath, so `acp-spring-boot-autoconfigure` built on JDK 21 had

acp-quarkus-deployment/pom.xml

@@ -112,6 +112,10 @@
                 <configuration>
                     <systemPropertyVariables>
                         <java.util.logging.manager>org.jboss.logmanager.LogManager</java.util.logging.manager>
+                        <!-- A random port, not Quarkus's fixed test port 8081, so that parallel
+                             builds on one machine do not collide; the tests read the port the
+                             server bound (@TestHTTPResource). -->
+                        <quarkus.http.test-port>0</quarkus.http.test-port>
                     </systemPropertyVariables>
                 </configuration>
             </plugin>

acp-quarkus-integration-tests/src/main/resources/application.properties

@@ -1,5 +1,6 @@
 greeting.prefix=Hello from Quarkus
 # The packaged application (prod) is a stdio agent; @QuarkusTest serves the same agent over HTTP.
 %test.quarkus.acp.agent.transport.type=http
-# The client bean, in tests: a Quarkus ACP client of the same application's agent.
+# The client bean, in tests: a Quarkus ACP client of the same application's agent. The test port
+# is a free one FreeTestPort picks, not Quarkus's fixed 8081, so that parallel builds do not collide.
 %test.quarkus.acp.client.transport.http.uri=http://localhost:${quarkus.http.test-port}/acp

acp-quarkus-integration-tests/src/test/java/com/agentclientprotocol/sdk/quarkus/it/ClientBeanTest.java

@@ -8,6 +8,8 @@
 
 import com.agentclientprotocol.sdk.client.AcpSyncClient;
 import com.agentclientprotocol.sdk.spec.AcpSchema;
+import io.quarkus.test.common.TestResourceScope;
+import io.quarkus.test.common.WithTestResource;
 import io.quarkus.test.junit.QuarkusTest;
 import jakarta.inject.Inject;
 import org.junit.jupiter.api.Test;
@@ -19,6 +21,7 @@
  * and customized by a bean, against the application's own agent over Streamable HTTP.
  */
 @QuarkusTest
+@WithTestResource(value = FreeTestPort.class, scope = TestResourceScope.GLOBAL)
 class ClientBeanTest {
 
 	@Inject

acp-quarkus-integration-tests/src/test/java/com/agentclientprotocol/sdk/quarkus/it/FreeTestPort.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2025-2026 the original author or authors.
+ */
+
+package com.agentclientprotocol.sdk.quarkus.it;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.net.ServerSocket;
+import java.util.Map;
+
+import io.quarkus.test.common.QuarkusTestResourceLifecycleManager;
+
+/**
+ * Serves the tests on a free port instead of Quarkus's fixed test port 8081, so that two builds on
+ * one machine do not collide. Not {@code quarkus.http.test-port=0}: the client bean's URI,
+ * {@code quarkus.acp.client.transport.http.uri}, is read when the application starts, before the
+ * server has bound a random port, so it would name port 0. A port picked here is known to both.
+ */
+public class FreeTestPort implements QuarkusTestResourceLifecycleManager {
+
+	@Override
+	public Map<String, String> start() {
+		try (ServerSocket socket = new ServerSocket(0)) {
+			return Map.of("quarkus.http.test-port", String.valueOf(socket.getLocalPort()));
+		}
+		catch (IOException ex) {
+			throw new UncheckedIOException(ex);
+		}
+	}
+
+	@Override
+	public void stop() {
+	}
+
+}