feat: fixes exception due to unread bytes in stream (#1897)

* feat: fixes exception due to unread bytes in stream

* feat: additonal unit tests to cover changes

* fix: automated changes by `make fix-import`

* fix: additonal changes by `make fix-import`

Co-authored-by: Adam Hopkins <admhpkns@gmail.com>

tests/test_request_stream.py

@@ -1,4 +1,5 @@
 import pytest
+import asyncio
 
 from sanic.blueprints import Blueprint
 from sanic.exceptions import HeaderExpectationFailed
@@ -6,6 +7,7 @@ from sanic.request import StreamBuffer
 from sanic.response import json, stream, text
 from sanic.views import CompositionView, HTTPMethodView
 from sanic.views import stream as stream_decorator
+from sanic.server import HttpProtocol
 
 
 data = "abc" * 1_000_000
@@ -337,6 +339,22 @@ def test_request_stream_handle_exception(app):
     assert "Method GET not allowed for URL /post/random_id" in response.text
 
 
+@pytest.mark.asyncio
+async def test_request_stream_unread(app):
+    """ensure no error is raised when leaving unread bytes in byte-buffer"""
+
+    err = None
+    protocol = HttpProtocol(loop=asyncio.get_event_loop(), app=app)
+    try:
+        protocol.request = None
+        protocol._body_chunks.append("this is a test")
+        await protocol.stream_append()
+    except AttributeError as e:
+        err = e
+
+    assert err is None and not protocol._body_chunks
+
+
 def test_request_stream_blueprint(app):
     """for self.is_request_stream = True"""
     bp = Blueprint("test_blueprint_request_stream_blueprint")