Added test that host with underscore accepted but properly causes UnknownHostException

Author: chernser

client-v2/src/test/java/com/clickhouse/client/ClientTests.java

@@ -5,6 +5,7 @@
 import com.clickhouse.client.api.ClientException;
 import com.clickhouse.client.api.ClientFaultCause;
 import com.clickhouse.client.api.ClientMisconfigurationException;
+import com.clickhouse.client.api.ConnectionInitiationException;
 import com.clickhouse.client.api.ConnectionReuseStrategy;
 import com.clickhouse.client.api.ServerException;
 import com.clickhouse.client.api.enums.Protocol;
@@ -30,6 +31,7 @@
 
 import java.io.ByteArrayInputStream;
 import java.net.ConnectException;
+import java.net.UnknownHostException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -569,6 +571,21 @@ public void testQueryIdGenerator() throws Exception {
         Assert.assertEquals(actualIds, new ArrayList<>(queryIds));
     }
 
+    @Test(groups = {"integration"})
+    public void testHostnameWithUnderscore() throws Exception {
+
+        try (Client client = new Client.Builder().addEndpoint("http://localhost_db:8123")
+                .setUsername("default")
+                .build()) {
+            client.queryAll("SELECT 1");
+            fail("Exception expected");
+        } catch (ClientException e) {
+            Assert.assertTrue(e.getCause() instanceof ConnectionInitiationException);
+            ConnectionInitiationException ce = (ConnectionInitiationException) e.getCause();
+            Assert.assertTrue(ce.getCause() instanceof UnknownHostException);
+        }
+    }
+
     public boolean isVersionMatch(String versionExpression, Client client) {
         List<GenericRecord> serverVersion = client.queryAll("SELECT version()");
         return ClickHouseVersion.of(serverVersion.get(0).getString(1)).check(versionExpression);