[Frontend][Docs] Transcription API streaming (#13301)

Signed-off-by: NickLucche <nlucches@redhat.com>

tests/entrypoints/openai/test_transcription_validation.py

@@ -3,12 +3,14 @@
 # imports for guided decoding tests
 import io
 import json
+from unittest.mock import patch
 
 import librosa
 import numpy as np
 import openai
 import pytest
 import soundfile as sf
+from openai._base_client import AsyncAPIClient
 
 from vllm.assets.audio import AudioAsset
 
@@ -120,3 +122,73 @@ async def test_completion_endpoints():
         res = await client.completions.create(model=model_name, prompt="Hello")
         assert res.code == 400
         assert res.message == "The model does not support Completions API"
+
+
+@pytest.mark.asyncio
+async def test_streaming_response(winning_call):
+    model_name = "openai/whisper-small"
+    server_args = ["--enforce-eager"]
+    transcription = ""
+    with RemoteOpenAIServer(model_name, server_args) as remote_server:
+        client = remote_server.get_async_client()
+        res_no_stream = await client.audio.transcriptions.create(
+            model=model_name,
+            file=winning_call,
+            response_format="json",
+            language="en",
+            temperature=0.0)
+        # Unfortunately this only works when the openai client is patched
+        # to use streaming mode, not exposed in the transcription api.
+        original_post = AsyncAPIClient.post
+
+        async def post_with_stream(*args, **kwargs):
+            kwargs['stream'] = True
+            return await original_post(*args, **kwargs)
+
+        with patch.object(AsyncAPIClient, "post", new=post_with_stream):
+            client = remote_server.get_async_client()
+            res = await client.audio.transcriptions.create(
+                model=model_name,
+                file=winning_call,
+                language="en",
+                temperature=0.0,
+                extra_body=dict(stream=True))
+            # Reconstruct from chunks and validate
+            async for chunk in res:
+                # just a chunk
+                text = chunk.choices[0]['delta']['content']
+                transcription += text
+
+        assert transcription == res_no_stream.text
+
+
+@pytest.mark.asyncio
+async def test_stream_options(winning_call):
+    model_name = "openai/whisper-small"
+    server_args = ["--enforce-eager"]
+    with RemoteOpenAIServer(model_name, server_args) as remote_server:
+        original_post = AsyncAPIClient.post
+
+        async def post_with_stream(*args, **kwargs):
+            kwargs['stream'] = True
+            return await original_post(*args, **kwargs)
+
+        with patch.object(AsyncAPIClient, "post", new=post_with_stream):
+            client = remote_server.get_async_client()
+            res = await client.audio.transcriptions.create(
+                model=model_name,
+                file=winning_call,
+                language="en",
+                temperature=0.0,
+                extra_body=dict(stream=True,
+                                stream_include_usage=True,
+                                stream_continuous_usage_stats=True))
+            final = False
+            continuous = True
+            async for chunk in res:
+                if not len(chunk.choices):
+                    # final usage sent
+                    final = True
+                else:
+                    continuous = continuous and hasattr(chunk, 'usage')
+            assert final and continuous