Address comment.

Author: viirya

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CastSuite.scala

@@ -996,28 +996,13 @@ class CastSuite extends SparkFunSuite with ExpressionEvalHelper {
 
     atomicTypes.foreach { atomicType =>
       val struct = Literal.create(
-        InternalRow(
-          UTF8String.fromString("123"),
-          UTF8String.fromString("true"),
-          UTF8String.fromString("f"),
-          null),
-        StructType(Seq(
-          StructField("a", StringType, nullable = true),
-          StructField("b", StringType, nullable = true),
-          StructField("c", StringType, nullable = true),
-          StructField("d", NullType, nullable = true))))
+        InternalRow(null),
+        StructType(Seq(StructField("a", NullType, nullable = true))))
 
       val ret = cast(struct, StructType(Seq(
-        StructField("a", StringType, nullable = true),
-        StructField("b", StringType, nullable = true),
-        StructField("c", StringType, nullable = true),
-        StructField("d", atomicType, nullable = true))))
+        StructField("a", atomicType, nullable = true))))
       assert(ret.resolved)
-      checkEvaluation(ret, InternalRow(
-        UTF8String.fromString("123"),
-        UTF8String.fromString("true"),
-        UTF8String.fromString("f"),
-        null))
+      checkEvaluation(ret, InternalRow(null))
     }
   }
 }

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

@@ -2159,7 +2159,7 @@ class DataFrameSuite extends QueryTest with SharedSQLContext {
   }
 
   test("SPARK-27671: Fix analysis exception when casting null in nested field in struct") {
-    val df = sql("select * FROM VALUES (('a', (10, null))), (('b', (10, 50))), " +
+    val df = sql("SELECT * FROM VALUES (('a', (10, null))), (('b', (10, 50))), " +
       "(('c', null)) AS tab(x, y)")
     checkAnswer(df, Row("a", Row(10, null)) :: Row("b", Row(10, 50)) :: Row("c", null) :: Nil)
   }