Add docs for 'result_index' usage and a system test.

docs/speech-usage.rst

@@ -31,8 +31,8 @@ create an instance of :class:`~google.cloud.speech.client.Client`.
     >>> client = speech.Client()
 
 
-Asychronous Recognition
------------------------
+Asynchronous Recognition
+------------------------
 
 The :meth:`~google.cloud.speech.Client.async_recognize` sends audio data to the
 Speech API and initiates a Long Running Operation. Using this operation, you
@@ -170,13 +170,13 @@ speech data to possible text alternatives on the fly.
     ...     for result in results:
     ...         for alternative in result.alternatives:
     ...             print('=' * 20)
+    ...             print('result_index: ' + str(result.result_index))
     ...             print('transcript: ' + alternative.transcript)
     ...             print('confidence: ' + str(alternative.confidence))
     ====================
     transcript: hello thank you for using Google Cloud platform
     confidence: 0.927983105183
 
-
 By default the API will perform continuous recognition
 (continuing to process audio even if the speaker in the audio pauses speaking)
 until the client closes the output stream or until the maximum time limit has

speech/tests/system.py

@@ -200,6 +200,7 @@ def test_stream_recognize(self):
 
         with open(AUDIO_FILE, 'rb') as file_obj:
             for results in self._make_streaming_request(file_obj):
+                self.assertIsInstance(results.result_index, int)
                 self._check_results(results.alternatives)
 
     def test_stream_recognize_interim_results(self):