fix: centralize discovery transport handling

tests/discovery/test_githubcode_contract.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import asyncio
 import contextlib
+import json
 from typing import TYPE_CHECKING, Any
 
 import pytest
@@ -18,6 +19,8 @@ class FakeResponse:
     def __init__(self, payload: dict[str, Any], links: dict[str, Any]) -> None:
         self.payload = payload
         self.links = links
+        self.headers: dict[str, str] = {}
+        self.content = self
 
     async def __aenter__(self) -> FakeResponse:
         return self
@@ -31,6 +34,9 @@ class FakeResponse:
     async def json(self) -> dict[str, Any]:
         return self.payload
 
+    async def iter_any(self):
+        yield json.dumps(self.payload).encode()
+
 
 @pytest.fixture
 def install_github_responses(monkeypatch: pytest.MonkeyPatch):
@@ -53,6 +59,10 @@ def install_github_responses(monkeypatch: pytest.MonkeyPatch):
                 requested_urls.append(url)
                 return next(response_iterator)
 
+            def request(self, method: str, url: str, **_kwargs: Any) -> FakeResponse:
+                assert method == 'GET'
+                return self.get(url)
+
         @contextlib.asynccontextmanager
         async def fake_open_session(**_kwargs: object) -> AsyncIterator[FakeSession]:
             async with FakeSession(headers={}) as session: