Use checkSQL.

Author: dongjoon-hyun

sql/hive/src/test/resources/sqlgen/predicate_subquery.sql

@@ -0,0 +1,4 @@
+-- This file is automatically generated by LogicalPlanToSQLSuite.
+select * from t1 b where exists (select * from t1 a)
+--------------------------------------------------------------------------------
+SELECT `gen_attr` AS `a` FROM (SELECT `gen_attr` FROM (SELECT `a` AS `gen_attr` FROM `default`.`t1`) AS gen_subquery_0 WHERE EXISTS(SELECT `gen_attr` AS `a` FROM ((SELECT `gen_attr` FROM (SELECT `a` AS `gen_attr` FROM `default`.`t1`) AS gen_subquery_0) AS gen_subquery_1) AS gen_subquery_1)) AS b

sql/hive/src/test/scala/org/apache/spark/sql/catalyst/LogicalPlanToSQLSuite.scala

@@ -25,6 +25,7 @@ import scala.util.control.NonFatal
 import org.apache.spark.sql.Column
 import org.apache.spark.sql.catalyst.parser.ParseException
 import org.apache.spark.sql.functions._
+import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.test.SQLTestUtils
 
 /**
@@ -929,9 +930,10 @@ class LogicalPlanToSQLSuite extends SQLBuilderTest with SQLTestUtils {
 
   test("predicate subquery") {
     withTable("t1") {
-      sql("CREATE TABLE t1(a int)")
-      val df = sql("select * from t1 b where exists (select * from t1 a)")
-      new SQLBuilder(df).toSQL
+      withSQLConf(SQLConf.CROSS_JOINS_ENABLED.key -> "true") {
+        sql("CREATE TABLE t1(a int)")
+        checkSQL("select * from t1 b where exists (select * from t1 a)", "predicate_subquery")
+      }
     }
   }