Add signals before and after handler execution (#2540)

tests/test_asgi.py

@@ -531,6 +531,8 @@ async def test_signals_triggered(app):
         "http.lifecycle.handle",
         "http.routing.before",
         "http.routing.after",
+        "http.handler.before",
+        "http.handler.after",
         "http.lifecycle.response",
         # "http.lifecycle.send",
         # "http.lifecycle.complete",

tests/test_handler.py

@@ -0,0 +1,36 @@
+from sanic.app import Sanic
+from sanic.response import empty
+from sanic.signals import Event
+
+
+def test_handler_operation_order(app: Sanic):
+    operations = []
+
+    @app.on_request
+    async def on_request(_):
+        nonlocal operations
+        operations.append(1)
+
+    @app.on_response
+    async def on_response(*_):
+        nonlocal operations
+        operations.append(5)
+
+    @app.get("/")
+    async def handler(_):
+        nonlocal operations
+        operations.append(3)
+        return empty()
+
+    @app.signal(Event.HTTP_HANDLER_BEFORE)
+    async def handler_before(**_):
+        nonlocal operations
+        operations.append(2)
+
+    @app.signal(Event.HTTP_HANDLER_AFTER)
+    async def handler_after(**_):
+        nonlocal operations
+        operations.append(4)
+
+    app.test_client.get("/")
+    assert operations == [1, 2, 3, 4, 5]