[SPARK-19709][SQL] Read empty file with CSV data source

## What changes were proposed in this pull request?

Bugfix for reading empty file with CSV data source. Instead of throwing `NoSuchElementException`, an empty data frame is returned.

## How was this patch tested?

Added new unit test in `org.apache.spark.sql.execution.datasources.csv.CSVSuite`

Author: Wojtek Szymanski <wk.szymanski@gmail.com>

Closes #17068 from wojtek-szymanski/SPARK-19709.

1 files changed, 4 insertions, 6 deletions

diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/csv/CSVSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/csv/CSVSuite.scala
index 56071803f6..eaedede349 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/csv/CSVSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/csv/CSVSuite.scala
@@ -1077,14 +1077,12 @@ class CSVSuite extends QueryTest with SharedSQLContext with SQLTestUtils {
     }
   }
 
-  test("Empty file produces empty dataframe with empty schema - wholeFile option") {
-    withTempPath { path =>
-      path.createNewFile()
-
+  test("Empty file produces empty dataframe with empty schema") {
+    Seq(false, true).foreach { wholeFile =>
       val df = spark.read.format("csv")
         .option("header", true)
-        .option("wholeFile", true)
-        .load(path.getAbsolutePath)
+        .option("wholeFile", wholeFile)
+        .load(testFile(emptyFile))
 
       assert(df.schema === spark.emptyDataFrame.schema)
       checkAnswer(df, spark.emptyDataFrame)