Merge pull request #4579 from lecovi/docs/#4574-test-typing

setup.cfg

@@ -87,7 +87,7 @@ per-file-ignores =
     src/flask/__init__.py: F401
 
 [mypy]
-files = src/flask
+files = src/flask, tests/typing
 python_version = 3.7
 show_error_codes = True
 allow_redefinition = True

src/flask/app.py

@@ -1033,7 +1033,7 @@ class Flask(Scaffold):
         self,
         rule: str,
         endpoint: t.Optional[str] = None,
-        view_func: t.Optional[t.Callable] = None,
+        view_func: t.Optional[ft.ViewCallable] = None,
         provide_automatic_options: t.Optional[bool] = None,
         **options: t.Any,
     ) -> None:
@@ -1681,7 +1681,7 @@ class Flask(Scaffold):
                 if isinstance(rv[1], (Headers, dict, tuple, list)):
                     rv, headers = rv
                 else:
-                    rv, status = rv  # type: ignore[misc]
+                    rv, status = rv  # type: ignore[assignment,misc]
             # other sized tuples are not allowed
             else:
                 raise TypeError(

src/flask/blueprints.py

@@ -384,7 +384,7 @@ class Blueprint(Scaffold):
         self,
         rule: str,
         endpoint: t.Optional[str] = None,
-        view_func: t.Optional[t.Callable] = None,
+        view_func: t.Optional[ft.ViewCallable] = None,
         provide_automatic_options: t.Optional[bool] = None,
         **options: t.Any,
     ) -> None:
@@ -561,12 +561,14 @@ class Blueprint(Scaffold):
         )
         return f
 
-    def app_errorhandler(self, code: t.Union[t.Type[Exception], int]) -> t.Callable:
+    def app_errorhandler(
+        self, code: t.Union[t.Type[Exception], int]
+    ) -> t.Callable[[ft.ErrorHandlerDecorator], ft.ErrorHandlerDecorator]:
         """Like :meth:`Flask.errorhandler` but for a blueprint.  This
         handler is used for all requests, even if outside of the blueprint.
         """
 
-        def decorator(f: ft.ErrorHandlerCallable) -> ft.ErrorHandlerCallable:
+        def decorator(f: ft.ErrorHandlerDecorator) -> ft.ErrorHandlerDecorator:
             self.record_once(lambda s: s.app.errorhandler(code)(f))
             return f
 

src/flask/scaffold.py

@@ -363,48 +363,60 @@ class Scaffold:
         method: str,
         rule: str,
         options: dict,
-    ) -> t.Callable[[F], F]:
+    ) -> t.Callable[[ft.RouteDecorator], ft.RouteDecorator]:
         if "methods" in options:
             raise TypeError("Use the 'route' decorator to use the 'methods' argument.")
 
         return self.route(rule, methods=[method], **options)
 
-    def get(self, rule: str, **options: t.Any) -> t.Callable[[F], F]:
+    def get(
+        self, rule: str, **options: t.Any
+    ) -> t.Callable[[ft.RouteDecorator], ft.RouteDecorator]:
         """Shortcut for :meth:`route` with ``methods=["GET"]``.
 
         .. versionadded:: 2.0
         """
         return self._method_route("GET", rule, options)
 
-    def post(self, rule: str, **options: t.Any) -> t.Callable[[F], F]:
+    def post(
+        self, rule: str, **options: t.Any
+    ) -> t.Callable[[ft.RouteDecorator], ft.RouteDecorator]:
         """Shortcut for :meth:`route` with ``methods=["POST"]``.
 
         .. versionadded:: 2.0
         """
         return self._method_route("POST", rule, options)
 
-    def put(self, rule: str, **options: t.Any) -> t.Callable[[F], F]:
+    def put(
+        self, rule: str, **options: t.Any
+    ) -> t.Callable[[ft.RouteDecorator], ft.RouteDecorator]:
         """Shortcut for :meth:`route` with ``methods=["PUT"]``.
 
         .. versionadded:: 2.0
         """
         return self._method_route("PUT", rule, options)
 
-    def delete(self, rule: str, **options: t.Any) -> t.Callable[[F], F]:
+    def delete(
+        self, rule: str, **options: t.Any
+    ) -> t.Callable[[ft.RouteDecorator], ft.RouteDecorator]:
         """Shortcut for :meth:`route` with ``methods=["DELETE"]``.
 
         .. versionadded:: 2.0
         """
         return self._method_route("DELETE", rule, options)
 
-    def patch(self, rule: str, **options: t.Any) -> t.Callable[[F], F]:
+    def patch(
+        self, rule: str, **options: t.Any
+    ) -> t.Callable[[ft.RouteDecorator], ft.RouteDecorator]:
         """Shortcut for :meth:`route` with ``methods=["PATCH"]``.
 
         .. versionadded:: 2.0
         """
         return self._method_route("PATCH", rule, options)
 
-    def route(self, rule: str, **options: t.Any) -> t.Callable[[F], F]:
+    def route(
+        self, rule: str, **options: t.Any
+    ) -> t.Callable[[ft.RouteDecorator], ft.RouteDecorator]:
         """Decorate a view function to register it with the given URL
         rule and options. Calls :meth:`add_url_rule`, which has more
         details about the implementation.
@@ -428,7 +440,7 @@ class Scaffold:
             :class:`~werkzeug.routing.Rule` object.
         """
 
-        def decorator(f: F) -> F:
+        def decorator(f: ft.RouteDecorator) -> ft.RouteDecorator:
             endpoint = options.pop("endpoint", None)
             self.add_url_rule(rule, endpoint, f, **options)
             return f
@@ -440,7 +452,7 @@ class Scaffold:
         self,
         rule: str,
         endpoint: t.Optional[str] = None,
-        view_func: t.Optional[t.Callable] = None,
+        view_func: t.Optional[ft.ViewCallable] = None,
         provide_automatic_options: t.Optional[bool] = None,
         **options: t.Any,
     ) -> None:
@@ -642,7 +654,7 @@ class Scaffold:
     @setupmethod
     def errorhandler(
         self, code_or_exception: t.Union[t.Type[Exception], int]
-    ) -> t.Callable[[ft.ErrorHandlerCallable], ft.ErrorHandlerCallable]:
+    ) -> t.Callable[[ft.ErrorHandlerDecorator], ft.ErrorHandlerDecorator]:
         """Register a function to handle errors by code or exception class.
 
         A decorator that is used to register a function given an
@@ -672,7 +684,7 @@ class Scaffold:
                                   an arbitrary exception
         """
 
-        def decorator(f: ft.ErrorHandlerCallable) -> ft.ErrorHandlerCallable:
+        def decorator(f: ft.ErrorHandlerDecorator) -> ft.ErrorHandlerDecorator:
             self.register_error_handler(code_or_exception, f)
             return f
 

src/flask/typing.py

@@ -1,37 +1,30 @@
 import typing as t
 
-
 if t.TYPE_CHECKING:
     from _typeshed.wsgi import WSGIApplication  # noqa: F401
     from werkzeug.datastructures import Headers  # noqa: F401
     from werkzeug.wrappers import Response  # noqa: F401
 
 # The possible types that are directly convertible or are a Response object.
-ResponseValue = t.Union[
-    "Response",
-    str,
-    bytes,
-    t.Dict[str, t.Any],  # any jsonify-able dict
-    t.Iterator[str],
-    t.Iterator[bytes],
-]
-StatusCode = int
+ResponseValue = t.Union["Response", str, bytes, t.Dict[str, t.Any]]
 
 # the possible types for an individual HTTP header
-HeaderName = str
+# This should be a Union, but mypy doesn't pass unless it's a TypeVar.
 HeaderValue = t.Union[str, t.List[str], t.Tuple[str, ...]]
 
 # the possible types for HTTP headers
 HeadersValue = t.Union[
-    "Headers", t.Dict[HeaderName, HeaderValue], t.List[t.Tuple[HeaderName, HeaderValue]]
+    "Headers",
+    t.Mapping[str, HeaderValue],
+    t.Sequence[t.Tuple[str, HeaderValue]],
 ]
 
 # The possible types returned by a route function.
 ResponseReturnValue = t.Union[
     ResponseValue,
     t.Tuple[ResponseValue, HeadersValue],
-    t.Tuple[ResponseValue, StatusCode],
-    t.Tuple[ResponseValue, StatusCode, HeadersValue],
+    t.Tuple[ResponseValue, int],
+    t.Tuple[ResponseValue, int, HeadersValue],
     "WSGIApplication",
 ]
 
@@ -51,6 +44,7 @@ TemplateGlobalCallable = t.Callable[..., t.Any]
 TemplateTestCallable = t.Callable[..., bool]
 URLDefaultCallable = t.Callable[[str, dict], None]
 URLValuePreprocessorCallable = t.Callable[[t.Optional[str], t.Optional[dict]], None]
+
 # This should take Exception, but that either breaks typing the argument
 # with a specific exception, or decorating multiple times with different
 # exceptions (and using a union type on the argument).
@@ -58,3 +52,7 @@ URLValuePreprocessorCallable = t.Callable[[t.Optional[str], t.Optional[dict]], N
 # https://github.com/pallets/flask/issues/4295
 # https://github.com/pallets/flask/issues/4297
 ErrorHandlerCallable = t.Callable[[t.Any], ResponseReturnValue]
+ErrorHandlerDecorator = t.TypeVar("ErrorHandlerDecorator", bound=ErrorHandlerCallable)
+
+ViewCallable = t.Callable[..., ResponseReturnValue]
+RouteDecorator = t.TypeVar("RouteDecorator", bound=ViewCallable)

tests/typing/typing_error_handler.py

@@ -0,0 +1,33 @@
+from __future__ import annotations
+
+from http import HTTPStatus
+
+from werkzeug.exceptions import BadRequest
+from werkzeug.exceptions import NotFound
+
+from flask import Flask
+
+app = Flask(__name__)
+
+
+@app.errorhandler(400)
+@app.errorhandler(HTTPStatus.BAD_REQUEST)
+@app.errorhandler(BadRequest)
+def handle_400(e: BadRequest) -> str:
+    return ""
+
+
+@app.errorhandler(ValueError)
+def handle_custom(e: ValueError) -> str:
+    return ""
+
+
+@app.errorhandler(ValueError)
+def handle_accept_base(e: Exception) -> str:
+    return ""
+
+
+@app.errorhandler(BadRequest)
+@app.errorhandler(404)
+def handle_multiple(e: BadRequest | NotFound) -> str:
+    return ""

tests/typing/typing_route.py

@@ -0,0 +1,62 @@
+from __future__ import annotations
+
+from http import HTTPStatus
+
+from flask import Flask
+from flask import jsonify
+from flask.templating import render_template
+from flask.views import View
+from flask.wrappers import Response
+
+app = Flask(__name__)
+
+
+@app.route("/str")
+def hello_str() -> str:
+    return "<p>Hello, World!</p>"
+
+
+@app.route("/bytes")
+def hello_bytes() -> bytes:
+    return b"<p>Hello, World!</p>"
+
+
+@app.route("/json")
+def hello_json() -> Response:
+    return jsonify({"response": "Hello, World!"})
+
+
+@app.route("/status")
+@app.route("/status/<int:code>")
+def tuple_status(code: int = 200) -> tuple[str, int]:
+    return "hello", code
+
+
+@app.route("/status-enum")
+def tuple_status_enum() -> tuple[str, int]:
+    return "hello", HTTPStatus.OK
+
+
+@app.route("/headers")
+def tuple_headers() -> tuple[str, dict[str, str]]:
+    return "Hello, World!", {"Content-Type": "text/plain"}
+
+
+@app.route("/template")
+@app.route("/template/<name>")
+def return_template(name: str | None = None) -> str:
+    return render_template("index.html", name=name)
+
+
+class RenderTemplateView(View):
+    def __init__(self: RenderTemplateView, template_name: str) -> None:
+        self.template_name = template_name
+
+    def dispatch_request(self: RenderTemplateView) -> str:
+        return render_template(self.template_name)
+
+
+app.add_url_rule(
+    "/about",
+    view_func=RenderTemplateView.as_view("about_page", template_name="about.html"),
+)