bug fixed sql parser grouping sets

src/test/java/com/alibaba/druid/bvt/sql/GroupingSetsTest.java

@@ -0,0 +1,19 @@
+package com.alibaba.druid.bvt.sql;
+
+import org.junit.Assert;
+
+import com.alibaba.druid.sql.SQLUtils;
+
+import junit.framework.TestCase;
+
+public class GroupingSetsTest extends TestCase {
+    public void test_groupingSets() throws Exception {
+        String sql = "SELECT brand, size, sum(sales) FROM items_sold GROUP BY GROUPING SETS ((brand), (size), ());";
+        
+        String result = SQLUtils.format(sql, null);
+        
+        Assert.assertEquals("SELECT brand, size, SUM(sales)"
+                + "\nFROM items_sold"
+                + "\nGROUP BY GROUPING SETS ((brand), (size), ());", result);
+    }
+}