Resolving some issues

Author: Paultagoras

jdbc-v2/src/main/java/com/clickhouse/jdbc/JdbcV2Wrapper.java

@@ -11,7 +11,7 @@ default boolean isWrapperFor(Class<?> iface) throws SQLException {
     @SuppressWarnings("unchecked")
     default <T> T unwrap(Class<T> iface) throws SQLException {
         if (isWrapperFor(iface)) {
-            iface.cast(this);
+            return iface.cast(this);
         }
         throw new SQLException("Cannot unwrap to " + iface.getName());
     }

jdbc-v2/src/main/java/com/clickhouse/jdbc/ResultSetImpl.java

@@ -57,8 +57,12 @@ public TableSchema getSchema() {
     public boolean next() throws SQLException {
         checkClosed();
 
-        Map<String, Object> currentRow = reader.next();
-        return currentRow != null;
+        try {
+            Map<String, Object> currentRow = reader.next();
+            return currentRow != null;
+        } catch (Exception e) {
+            throw ExceptionUtils.toSqlState(e);
+        }
     }
 
     @Override

jdbc-v2/src/test/java/com/clickhouse/jdbc/ConnectionTest.java

@@ -308,7 +308,7 @@ public void setShardingKeyTest() throws SQLException {
        assertThrows(SQLFeatureNotSupportedException.class, () -> localConnection.setShardingKey(null, null));
     }
 
-    @Test
+    @Test(groups = { "integration" })
     public void testMaxResultRowsProperty() throws Exception {
         Properties properties = new Properties();
         properties.setProperty(Driver.chSettingKey(ServerSettings.MAX_RESULT_ROWS), "5");
@@ -323,7 +323,7 @@ public void testMaxResultRowsProperty() throws Exception {
         }
     }
 
-    @Test
+    @Test(groups = { "integration" })
     public void testSecureConnection() throws Exception {
         if (isCloud()) {
             return; // this test uses self-signed cert
@@ -357,7 +357,7 @@ public void testSecureConnection() throws Exception {
         }
     }
 
-    @Test
+    @Test(groups = { "integration" })
     public void testSelectingDatabase() throws Exception {
         ClickHouseNode server = getServer(ClickHouseProtocol.HTTP);
         Properties properties = new Properties();
@@ -394,4 +394,14 @@ public void testSelectingDatabase() throws Exception {
             Assert.assertEquals(rs.getString(1), "system");
         }
     }
+
+    @Test(groups = { "integration" })
+    public void testUnwrapping() throws Exception {
+        Connection conn = getJdbcConnection();
+        Assert.assertTrue(conn.isWrapperFor(Connection.class));
+        Assert.assertTrue(conn.isWrapperFor(JdbcV2Wrapper.class));
+        Assert.assertEquals(conn.unwrap(Connection.class), conn);
+        Assert.assertEquals(conn.unwrap(JdbcV2Wrapper.class), conn);
+        assertThrows(SQLException.class, () -> conn.unwrap(ResultSet.class));
+    }
 }