also check multiLine codepath and selecting empty schema with count

Author: koertkuipers

sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/csv/CSVSuite.scala

@@ -1605,19 +1605,33 @@ class CSVSuite extends QueryTest with SharedSQLContext with SQLTestUtils with Te
 
   test("SPARK-25134: check header on parsing of dataset with projection and column pruning") {
     withSQLConf(SQLConf.CSV_PARSER_COLUMN_PRUNING.key -> "true") {
-      withTempPath { path =>
-        val dir = path.getAbsolutePath
-        Seq(("a", "b")).toDF("columnA", "columnB").write
-          .format("csv")
-          .option("header", true)
-          .save(dir)
-        checkAnswer(spark.read
-          .format("csv")
-          .option("header", true)
-          .option("enforceSchema", false)
-          .load(dir)
-          .select("columnA"),
-          Row("a"))
+      Seq(false, true).foreach { multiLine =>
+        withTempPath { path =>
+          val dir = path.getAbsolutePath
+          Seq(("a", "b")).toDF("columnA", "columnB").write
+            .format("csv")
+            .option("header", true)
+            .save(dir)
+
+          // schema with one column
+          checkAnswer(spark.read
+            .format("csv")
+            .option("header", true)
+            .option("enforceSchema", false)
+            .option("multiLine", multiLine)
+            .load(dir)
+            .select("columnA"),
+            Row("a"))
+
+          // empty schema
+          assert(spark.read
+            .format("csv")
+            .option("header", true)
+            .option("enforceSchema", false)
+            .option("multiLine", multiLine)
+            .load(dir)
+            .count() === 1L)
+        }
       }
     }
   }