Revert "removal of the unit test for the now deprecated callUdf"

Author: BenFradet

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

@@ -301,6 +301,15 @@ class DataFrameSuite extends QueryTest {
     )
   }
 
+  test("deprecated callUdf in SQLContext") {
+    val df = Seq(("id1", 1), ("id2", 4), ("id3", 5)).toDF("id", "value")
+    val sqlctx = df.sqlContext
+    sqlctx.udf.register("simpleUdf", (v: Int) => v * v)
+    checkAnswer(
+      df.select($"id", callUdf("simpleUdf", $"value")),
+      Row("id1", 1) :: Row("id2", 16) :: Row("id3", 25) :: Nil)
+  }
+
   test("callUDF in SQLContext") {
     val df = Seq(("id1", 1), ("id2", 4), ("id3", 5)).toDF("id", "value")
     val sqlctx = df.sqlContext