diff --git a/python/pyspark/streaming_tests.py b/python/pyspark/streaming_tests.py
index ef308fdd6aa59..c35d352c66ca5 100644
--- a/python/pyspark/streaming_tests.py
+++ b/python/pyspark/streaming_tests.py
@@ -275,7 +275,7 @@ def test_func(dstream):
         self.assertEqual(expected_output, output)
 
     def test_mapPartitions_batch(self):
-        """Basic operation test for DStream.mapPartitions with batch deserializer"""
+        """Basic operation test for DStream.mapPartitions with batch deserializer."""
         test_input = [range(1, 5), range(5, 9), range(9, 13)]
         numSlices = 2
 
@@ -288,7 +288,7 @@ def f(iterator):
         self.assertEqual(expected_output, output)
 
     def test_mapPartitions_unbatch(self):
-        """Basic operation test for DStream.mapPartitions with unbatch deserializer"""
+        """Basic operation test for DStream.mapPartitions with unbatch deserializer."""
         test_input = [range(1, 4), range(4, 7), range(7, 10)]
         numSlices = 2
 
@@ -301,8 +301,8 @@ def f(iterator):
         self.assertEqual(expected_output, output)
 
     def test_countByValue_batch(self):
-        """Basic operation test for DStream.countByValue with batch deserializer"""
-        test_input = [range(1, 5) + range(1,5), range(5, 7) + range(5, 9), ["a"] * 2 + ["b"] + [""] ]
+        """Basic operation test for DStream.countByValue with batch deserializer."""
+        test_input = [range(1, 5) + range(1,5), range(5, 7) + range(5, 9), ["a", "a", "b", ""]]
 
         def test_func(dstream):
             return dstream.countByValue()
@@ -315,7 +315,7 @@ def test_func(dstream):
         self.assertEqual(expected_output, output)
 
     def test_countByValue_unbatch(self):
-        """Basic operation test for DStream.countByValue with unbatch deserializer"""
+        """Basic operation test for DStream.countByValue with unbatch deserializer."""
         test_input = [range(1, 4), [1, 1, ""], ["a", "a", "b"]]
 
         def test_func(dstream):
@@ -328,30 +328,72 @@ def test_func(dstream):
             self._sort_result_based_on_key(result)
         self.assertEqual(expected_output, output)
 
+    def test_groupByKey_batch(self):
+        """Basic operation test for DStream.groupByKey with batch deserializer."""
+        test_input = [range(1, 5), [1, 1, 1, 2, 2, 3], ["a", "a", "b", "", "", ""]]
+        def test_func(dstream):
+            return dstream.map(lambda x: (x,1)).groupByKey()
+        expected_output = [[(1, [1]), (2, [1]), (3, [1]), (4, [1])],
+                           [(1, [1, 1, 1]), (2, [1, 1]), (3, [1])],
+                           [("a", [1, 1]), ("b", [1]), ("", [1, 1, 1])]]
+        scattered_output = self._run_stream(test_input, test_func, expected_output)
+        output = self._convert_iter_value_to_list(scattered_output)
+        for result in (output, expected_output):
+            self._sort_result_based_on_key(result)
+        self.assertEqual(expected_output, output)
+
+    def test_groupByKey_unbatch(self):
+        """Basic operation test for DStream.groupByKey with unbatch deserializer."""
+        test_input = [range(1, 4), [1, 1, ""], ["a", "a", "b"]]
+        def test_func(dstream):
+            return dstream.map(lambda x: (x,1)).groupByKey()
+        expected_output = [[(1, [1]), (2, [1]), (3, [1])],
+                           [(1, [1, 1]), ("", [1])],
+                           [("a", [1, 1]), ("b", [1])]]
+        scattered_output = self._run_stream(test_input, test_func, expected_output)
+        output = self._convert_iter_value_to_list(scattered_output)
+        for result in (output, expected_output):
+            self._sort_result_based_on_key(result)
+        self.assertEqual(expected_output, output)
+
+    def _convert_iter_value_to_list(self, outputs):
+        """Return key value pair list. Value is converted to iterator to list."""
+        result = list()
+        for output in outputs:
+            result.append(map(lambda (x, y): (x, list(y)), output))
+        return result
+
     def _sort_result_based_on_key(self, outputs):
+        """Sort the list base onf first value."""
         for output in outputs:
             output.sort(key=lambda x: x[0])
 
     def _run_stream(self, test_input, test_func, expected_output, numSlices=None):
-        """Start stream and return the output"""
-        # Generate input stream with user-defined input
+        """
+        Start stream and return the output.
+        @param test_input: dataset for the test. This should be list of lists.
+        @param test_func: wrapped test_function. This function should return PythonDstream object.
+        @param expexted_output: expected output for this testcase.
+        @param numSlices: the number of slices in the rdd in the dstream.
+        """
+        # Generate input stream with user-defined input.
         numSlices = numSlices or self.numInputPartitions
         test_input_stream = self.ssc._testInputStream(test_input, numSlices)
-        # Apply test function to stream
+        # Apply test function to stream.
         test_stream = test_func(test_input_stream)
-        # Add job to get output from stream
+        # Add job to get output from stream.
         test_stream._test_output(self.result)
         self.ssc.start()
 
         start_time = time.time()
-        # loop until get the result from stream
+        # Loop until get the expected the number of the result from the stream.
         while True:
             current_time = time.time()
-            # check time out
+            # Check time out.
             if (current_time - start_time) > self.timeout:
                 break
             self.ssc.awaitTermination(50)
-            # check if the output is the same length of expexted output
+            # Check if the output is the same length of expexted output.
             if len(expected_output) == len(self.result):
                 break
 
@@ -372,9 +414,5 @@ def tearDownClass(cls):
         PySparkStreamingTestCase.tearDownClass()
 
 
-
-
-
-
 if __name__ == "__main__":
     unittest.main()