test: Use mock to eliminate BookieSocketAddressTest dependency on local system configuration (#4711)

- Replace direct network calls with Mockito mocks in BookieSocketAddressTest
- Add mockHostnameIPSetup helper method to simulate DNS.getDefaultIP behavior
- Remove dependency on actual network configuration and loopback addresses
- Ensure consistent test behavior across different environments
- All 4 existing tests pass with the mock implementation

Co-authored-by: JiangHaiting <jasonxjiang@tencent.com>
Co-authored-by: Lari Hotari <lhotari@users.noreply.github.com>

Author: 3 people

bookkeeper-server/src/test/java/org/apache/bookkeeper/bookie/BookieSocketAddressTest.java

@@ -22,14 +22,22 @@
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 import com.google.common.net.InetAddresses;
-import java.net.InetAddress;
 import java.net.UnknownHostException;
 import org.apache.bookkeeper.conf.ServerConfiguration;
 import org.apache.bookkeeper.net.BookieSocketAddress;
+import org.apache.bookkeeper.net.DNS;
 import org.junit.Test;
+import org.mockito.MockedStatic;
+import org.mockito.Mockito;
 
 public class BookieSocketAddressTest {
 
+    private MockedStatic<DNS> mockHostnameIPSetup(String mockHostAddress) {
+        MockedStatic<DNS> mockedDNS = Mockito.mockStatic(DNS.class);
+        mockedDNS.when(() -> DNS.getDefaultIP("default")).thenReturn(mockHostAddress);
+        return mockedDNS;
+    }
+
     private void testAdvertisedWithLoopbackAddress(String address) throws UnknownHostException {
         ServerConfiguration conf = new ServerConfiguration();
         conf.setAdvertisedAddress(address);
@@ -49,29 +57,38 @@ public void testAdvertisedWithLoopbackAddress() throws UnknownHostException {
 
     @Test
     public void testAdvertisedWithNonLoopbackAddress() throws UnknownHostException {
-        String hostAddress = InetAddress.getLocalHost().getHostAddress();
-        if (hostAddress == null) {
-            throw new UnknownHostException("Host address is null");
+        // Mock to return a non-loopback address
+        try (MockedStatic<DNS> mockedDNS = mockHostnameIPSetup("192.168.1.100")) {
+            ServerConfiguration conf = new ServerConfiguration();
+            conf.setAllowLoopback(false);
+            conf.setAdvertisedAddress("192.168.1.100");
+            BookieSocketAddress bookieAddress = getBookieAddress(conf);
+            assertThat(bookieAddress.getHostName()).isEqualTo("192.168.1.100");
         }
-        ServerConfiguration conf = new ServerConfiguration();
-        conf.setAllowLoopback(false);
-        conf.setAdvertisedAddress(hostAddress);
-        BookieSocketAddress bookieAddress = getBookieAddress(conf);
-        assertThat(bookieAddress.getHostName()).isEqualTo(hostAddress);
     }
 
     @Test
     public void testBookieAddressIsIPAddressByDefault() throws UnknownHostException {
-        ServerConfiguration conf = new ServerConfiguration();
-        BookieSocketAddress bookieAddress = getBookieAddress(conf);
-        assertThat(InetAddresses.isInetAddress(bookieAddress.getHostName())).isTrue();
+        // Mock to return a non-loopback address
+        try (MockedStatic<DNS> mockedDNS = mockHostnameIPSetup("192.168.1.100")) {
+            ServerConfiguration conf = new ServerConfiguration();
+            // Do not allow loopback addresses
+            conf.setAllowLoopback(false);
+            BookieSocketAddress bookieAddress = getBookieAddress(conf);
+            assertThat(InetAddresses.isInetAddress(bookieAddress.getHostName())).isTrue();
+        }
     }
 
     @Test
     public void testBookieAddressIsHostname() throws UnknownHostException {
-        ServerConfiguration conf = new ServerConfiguration();
-        conf.setUseHostNameAsBookieID(true);
-        BookieSocketAddress bookieAddress = getBookieAddress(conf);
-        assertThat(InetAddresses.isInetAddress(bookieAddress.getHostName())).isFalse();
+        // Mock to return localhost address which can be resolved to a hostname
+        try (MockedStatic<DNS> mockedDNS = mockHostnameIPSetup("127.0.0.1")) {
+            ServerConfiguration conf = new ServerConfiguration();
+            conf.setUseHostNameAsBookieID(true);
+            // Allow loopback addresses since we're testing hostname resolution
+            conf.setAllowLoopback(true);
+            BookieSocketAddress bookieAddress = getBookieAddress(conf);
+            assertThat(InetAddresses.isInetAddress(bookieAddress.getHostName())).isFalse();
+        }
     }
 }