Add a comment to explain what tht test is for

HyukjinKwon · HyukjinKwon · commit 0d5b5861f248 · 2017-01-15T22:21:50.000+09:00
diff --git a/sql/core/src/test/java/test/org/apache/spark/sql/JavaUDFSuite.java b/sql/core/src/test/java/test/org/apache/spark/sql/JavaUDFSuite.java
@@ -121,6 +121,7 @@ public Long call(Long i) {
     }, DataTypes.LongType);
 
     spark.range(10).toDF("x").createOrReplaceTempView("tmp");
+    // This tests when Java UDFs are required to be the semantically same (See SPARK-9435).
     List<Row> results = spark.sql("SELECT inc(x) FROM tmp GROUP BY inc(x)").collectAsList();
     Assert.assertEquals(10, results.size());
     long sum = 0;
