add some comment

Author: peter-toth

sql/core/src/test/scala/org/apache/spark/sql/SQLQueryTestSuite.scala

@@ -390,6 +390,12 @@ class SQLQueryTestSuite extends QueryTest with SharedSparkSession {
     }
   }
 
+  /**
+   * This method handles exceptions occurred during query execution as they may need special care
+   * to become comparable to the expected output.
+   *
+   * @param result a function that returns a pair of schema and output
+   */
   protected def handleExceptions(result: => (String, Seq[String])): (String, Seq[String]) = {
     try {
       result

sql/hive-thriftserver/src/test/scala/org/apache/spark/sql/hive/thriftserver/ThriftServerQueryTestSuite.scala

@@ -255,6 +255,7 @@ class ThriftServerQueryTestSuite extends SQLQueryTestSuite {
     }
   }
 
+  /** ThriftServer wraps the root exception, so it needs to be extracted. */
   override def handleExceptions(result: => (String, Seq[String])): (String, Seq[String]) = {
     super.handleExceptions {
       try {