Add convenience for annotated handlers (#2225)

tests/test_handler_annotations.py

@@ -0,0 +1,39 @@
+from uuid import UUID
+
+import pytest
+
+from sanic import json
+
+
+@pytest.mark.parametrize(
+    "idx,path,expectation",
+    (
+        (0, "/abc", "str"),
+        (1, "/123", "int"),
+        (2, "/123.5", "float"),
+        (3, "/8af729fe-2b94-4a95-a168-c07068568429", "UUID"),
+    ),
+)
+def test_annotated_handlers(app, idx, path, expectation):
+    def build_response(num, foo):
+        return json({"num": num, "type": type(foo).__name__})
+
+    @app.get("/<foo>")
+    def handler0(_, foo: str):
+        return build_response(0, foo)
+
+    @app.get("/<foo>")
+    def handler1(_, foo: int):
+        return build_response(1, foo)
+
+    @app.get("/<foo>")
+    def handler2(_, foo: float):
+        return build_response(2, foo)
+
+    @app.get("/<foo>")
+    def handler3(_, foo: UUID):
+        return build_response(3, foo)
+
+    _, response = app.test_client.get(path)
+    assert response.json["num"] == idx
+    assert response.json["type"] == expectation