diff --git a/streaming/src/main/scala/org/apache/spark/streaming/api/python/PythonDStream.scala b/streaming/src/main/scala/org/apache/spark/streaming/api/python/PythonDStream.scala
index 15104e464d48e..27e74a847a4ad 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/api/python/PythonDStream.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/api/python/PythonDStream.scala
@@ -170,8 +170,8 @@ class PythonForeachDStream(
 
 /**
  * This is a input stream just for the unitest. This is equivalent to a checkpointable,
- * replayable, reliable message queue like Kafka. It requires a sequence as input, and
- * returns the i_th element at the i_th batch under manual clock.
+ * replayable, reliable message queue like Kafka. It requires a JArrayList input of JavaRDD,
+ * and returns the i_th element at the i_th batch under manual clock.
  */
 
 class PythonTestInputStream(ssc_ : JavaStreamingContext,