SEC-2558: Fix failing ApacheDSContainerTests when port is taken

ldap/src/integration-test/java/org/springframework/security/ldap/server/ApacheDSContainerTests.java

@@ -17,6 +17,11 @@ package org.springframework.security.ldap.server;
 
 import static junit.framework.Assert.fail;
 
+import java.io.IOException;
+import java.net.ServerSocket;
+import java.util.ArrayList;
+import java.util.List;
+
 import org.junit.Test;
 
 /**
@@ -32,7 +37,10 @@ public class ApacheDSContainerTests {
     @Test
     public void failsToStartThrowsException() throws Exception {
         ApacheDSContainer server1 = new ApacheDSContainer("dc=springframework,dc=org", "classpath:test-server.ldif");
-        ApacheDSContainer server2 = new ApacheDSContainer("dc=springframework,dc=org", "classpath:test-server.ldif");
+        ApacheDSContainer server2 = new ApacheDSContainer("dc=springframework,dc=org", "classpath:missing.ldif");
+        List<Integer> ports = getDefaultPorts(1);
+        server1.setPort(ports.get(0));
+        server2.setPort(ports.get(0));
         try {
             server1.afterPropertiesSet();
             try {
@@ -54,6 +62,9 @@ public class ApacheDSContainerTests {
     public void multipleInstancesSimultanciously() throws Exception {
         ApacheDSContainer server1 = new ApacheDSContainer("dc=springframework,dc=org", "classpath:test-server.ldif");
         ApacheDSContainer server2 = new ApacheDSContainer("dc=springframework,dc=org", "classpath:test-server.ldif");
+        List<Integer> ports = getDefaultPorts(2);
+        server1.setPort(ports.get(0));
+        server2.setPort(ports.get(1));
         try {
             server1.afterPropertiesSet();
             server2.afterPropertiesSet();
@@ -66,4 +77,21 @@ public class ApacheDSContainerTests {
             }catch(Throwable t) {}
         }
     }
+
+    private List<Integer> getDefaultPorts(int count) throws IOException {
+        List<ServerSocket> connections = new ArrayList<ServerSocket>();
+        List<Integer> availablePorts = new ArrayList<Integer>(count);
+        try {
+            for(int i=0;i<count;i++) {
+                ServerSocket socket = new ServerSocket(0);
+                connections.add(socket);
+                availablePorts.add(socket.getLocalPort());
+            }
+            return availablePorts;
+        } finally {
+            for(ServerSocket conn : connections) {
+                conn.close();
+            }
+        }
+    }
 }