feat(test): Use dynamic port allocation in integration tests (#133)

- Add TestUtil class with findAvailablePort() method to the mcp-test module
- Add findAvailablePort() method to TomcatTestUtil classes
- Replace hardcoded port numbers with dynamic port allocation

Signed-off-by: Christian Tzolov <christian.tzolov@broadcom.com>

mcp/src/test/java/io/modelcontextprotocol/server/transport/HttpServletSseServerCustomContextPathTests.java

@@ -4,6 +4,7 @@
 package io.modelcontextprotocol.server.transport;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
+
 import io.modelcontextprotocol.client.McpClient;
 import io.modelcontextprotocol.client.transport.HttpClientSseClientTransport;
 import io.modelcontextprotocol.server.McpServer;
@@ -17,9 +18,9 @@ import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
-public class HttpServletSseServerCustomContextPathTests {
+class HttpServletSseServerCustomContextPathTests {
 
-	private static final int PORT = 8195;
+	private static final int PORT = TomcatTestUtil.findAvailablePort();
 
 	private static final String CUSTOM_CONTEXT_PATH = "/api/v1";
 
@@ -48,7 +49,7 @@ public class HttpServletSseServerCustomContextPathTests {
 
 		try {
 			tomcat.start();
-			assertThat(tomcat.getServer().getState() == LifecycleState.STARTED);
+			assertThat(tomcat.getServer().getState()).isEqualTo(LifecycleState.STARTED);
 		}
 		catch (Exception e) {
 			throw new RuntimeException("Failed to start Tomcat", e);

mcp/src/test/java/io/modelcontextprotocol/server/transport/HttpServletSseServerTransportProviderIntegrationTests.java

@@ -12,6 +12,7 @@ import java.util.function.Function;
 import java.util.stream.Collectors;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
+
 import io.modelcontextprotocol.client.McpClient;
 import io.modelcontextprotocol.client.transport.HttpClientSseClientTransport;
 import io.modelcontextprotocol.server.McpServer;
@@ -44,9 +45,9 @@ import static org.assertj.core.api.Assertions.assertThat;
 import static org.awaitility.Awaitility.await;
 import static org.mockito.Mockito.mock;
 
-public class HttpServletSseServerTransportProviderIntegrationTests {
+class HttpServletSseServerTransportProviderIntegrationTests {
 
-	private static final int PORT = 8189;
+	private static final int PORT = TomcatTestUtil.findAvailablePort();
 
 	private static final String CUSTOM_SSE_ENDPOINT = "/somePath/sse";
 
@@ -70,7 +71,7 @@ public class HttpServletSseServerTransportProviderIntegrationTests {
 		tomcat = TomcatTestUtil.createTomcatServer("", PORT, mcpServerTransportProvider);
 		try {
 			tomcat.start();
-			assertThat(tomcat.getServer().getState() == LifecycleState.STARTED);
+			assertThat(tomcat.getServer().getState()).isEqualTo(LifecycleState.STARTED);
 		}
 		catch (Exception e) {
 			throw new RuntimeException("Failed to start Tomcat", e);
@@ -133,7 +134,7 @@ public class HttpServletSseServerTransportProviderIntegrationTests {
 	}
 
 	@Test
-	void testCreateMessageSuccess() throws InterruptedException {
+	void testCreateMessageSuccess() {
 
 		Function<CreateMessageRequest, CreateMessageResult> samplingHandler = request -> {
 			assertThat(request.messages()).hasSize(1);

mcp/src/test/java/io/modelcontextprotocol/server/transport/TomcatTestUtil.java

@@ -3,19 +3,23 @@
 */
 package io.modelcontextprotocol.server.transport;
 
-import com.fasterxml.jackson.databind.ObjectMapper;
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.net.ServerSocket;
+
 import jakarta.servlet.Servlet;
 import org.apache.catalina.Context;
-import org.apache.catalina.LifecycleState;
 import org.apache.catalina.startup.Tomcat;
 
-import static org.junit.Assert.assertThat;
-
 /**
  * @author Christian Tzolov
  */
 public class TomcatTestUtil {
 
+	TomcatTestUtil() {
+		// Prevent instantiation
+	}
+
 	public static Tomcat createTomcatServer(String contextPath, int port, Servlet servlet) {
 
 		var tomcat = new Tomcat();
@@ -24,7 +28,6 @@ public class TomcatTestUtil {
 		String baseDir = System.getProperty("java.io.tmpdir");
 		tomcat.setBaseDir(baseDir);
 
-		// Context context = tomcat.addContext("", baseDir);
 		Context context = tomcat.addContext(contextPath, baseDir);
 
 		// Add transport servlet to Tomcat
@@ -42,4 +45,19 @@ public class TomcatTestUtil {
 		return tomcat;
 	}
 
+	/**
+	 * Finds an available port on the local machine.
+	 * @return an available port number
+	 * @throws IllegalStateException if no available port can be found
+	 */
+	public static int findAvailablePort() {
+		try (final ServerSocket socket = new ServerSocket()) {
+			socket.bind(new InetSocketAddress(0));
+			return socket.getLocalPort();
+		}
+		catch (final IOException e) {
+			throw new IllegalStateException("Cannot bind to an available port!", e);
+		}
+	}
+
 }