Python: Make fetch work with Python Request as argument (#4926)

Author: hoodmane

src/pyodide/internal/_workers.py

@@ -220,14 +220,16 @@ def json(self, *args: Never, **kwargs: Never):
 
 if pyodide_version == "0.26.0a2":
 
-    async def _pyfetch_patched(url: str, **kwargs: Any) -> "Response":
+    async def _pyfetch_patched(
+        request: "str | js.Request", **kwargs: Any
+    ) -> "Response":
         # This is copied from https://github.com/pyodide/pyodide/blob/d3f99e1d/src/py/pyodide/http.py
         custom_fetch = kwargs["fetcher"] if "fetcher" in kwargs else js.fetch
         kwargs["fetcher"] = None
         try:
             return Response(
                 await custom_fetch(
-                    url, to_js(kwargs, dict_converter=Object.fromEntries)
+                    request, to_js(kwargs, dict_converter=Object.fromEntries)
                 ),
             )
         except JsException as e:
@@ -237,9 +239,11 @@ async def _pyfetch_patched(url: str, **kwargs: Any) -> "Response":
 
 
 async def fetch(
-    resource: str,
+    resource: "str | Request | js.Request",
     **other_options: Unpack[FetchKwargs],
 ) -> "Response":
+    if isinstance(resource, Request):
+        resource = resource.js_object
     if "method" in other_options and isinstance(other_options["method"], HTTPMethod):
         other_options["method"] = other_options["method"].value
     resp = await _pyfetch_patched(resource, **other_options)

src/workerd/server/tests/python/sdk/worker.py

@@ -170,6 +170,7 @@ async def test(self):
         await request_unit_tests(js_env)
         await can_use_event_decorator(js_env)
         await response_unit_tests(js_env)
+        await can_fetch_python_request()
 
 
 # TODO: Right now the `fetch` that's available on a binding is the JS fetch.
@@ -495,3 +496,11 @@ def __init__(self, x):
     )
     # TODO: it doesn't seem possible to access webSocket even in JS
     assert response_ws.status == 201
+
+
+async def can_fetch_python_request():
+    def fetch_check(request, opts):
+        assert isinstance(request, JsProxy)
+
+    async with _mock_fetch(fetch_check):
+        await fetch(Request("https://example.com/redirect"))