🚨 Cover protocols/http/flow_control.py on mypy (#1061)

Co-authored-by: euri10 <euri10@users.noreply.github.com>

setup.cfg

@@ -27,6 +27,7 @@ files =
     uvicorn/__init__.py,
     uvicorn/__main__.py,
     uvicorn/subprocess.py,
+    uvicorn/protocols/http/flow_control.py,
     uvicorn/supervisors/statreload.py,
     uvicorn/supervisors/multiprocess.py
 

uvicorn/protocols/http/flow_control.py

@@ -1,5 +1,13 @@
 import asyncio
 
+from asgiref.typing import (
+    ASGIReceiveCallable,
+    ASGISendCallable,
+    HTTPResponseBodyEvent,
+    HTTPResponseStartEvent,
+    Scope,
+)
+
 CLOSE_HEADER = (b"connection", b"close")
 
 HIGH_WATER_LIMIT = 65536
@@ -8,46 +16,53 @@
 
 
 class FlowControl:
-    def __init__(self, transport):
+    def __init__(self, transport: asyncio.Transport) -> None:
         self._transport = transport
         self.read_paused = False
         self.write_paused = False
         self._is_writable_event = asyncio.Event()
         self._is_writable_event.set()
 
-    async def drain(self):
+    async def drain(self) -> None:
         await self._is_writable_event.wait()
 
-    def pause_reading(self):
+    def pause_reading(self) -> None:
         if not self.read_paused:
             self.read_paused = True
             self._transport.pause_reading()
 
-    def resume_reading(self):
+    def resume_reading(self) -> None:
         if self.read_paused:
             self.read_paused = False
             self._transport.resume_reading()
 
-    def pause_writing(self):
+    def pause_writing(self) -> None:
         if not self.write_paused:
             self.write_paused = True
             self._is_writable_event.clear()
 
-    def resume_writing(self):
+    def resume_writing(self) -> None:
         if self.write_paused:
             self.write_paused = False
             self._is_writable_event.set()
 
 
-async def service_unavailable(scope, receive, send):
-    await send(
-        {
-            "type": "http.response.start",
-            "status": 503,
-            "headers": [
-                (b"content-type", b"text/plain; charset=utf-8"),
-                (b"connection", b"close"),
-            ],
-        }
-    )
-    await send({"type": "http.response.body", "body": b"Service Unavailable"})
+async def service_unavailable(
+    scope: Scope, receive: ASGIReceiveCallable, send: ASGISendCallable
+) -> None:
+    response_start: HTTPResponseStartEvent = {
+        "type": "http.response.start",
+        "status": 503,
+        "headers": [
+            (b"content-type", b"text/plain; charset=utf-8"),
+            (b"connection", b"close"),
+        ],
+    }
+    await send(response_start)
+
+    response_body: HTTPResponseBodyEvent = {
+        "type": "http.response.body",
+        "body": b"Service Unavailable",
+        "more_body": False,
+    }
+    await send(response_body)