Fix two environment-specific test failures

scrapy/throttling.py

@@ -800,11 +800,9 @@ class ThrottlingScopeManagerProtocol(Protocol):
     """
 
     @classmethod
-    def from_crawler(cls, crawler: Crawler, config: dict[str, Any]) -> Self:
-        return cls(crawler, config)
+    def from_crawler(cls, crawler: Crawler, config: dict[str, Any]) -> Self: ...
 
-    def __init__(self, crawler: Crawler, config: dict[str, Any]) -> None:
-        pass
+    def __init__(self, crawler: Crawler, config: dict[str, Any]) -> None: ...
 
     def can_send(self, now: float | None = None, amount: float | None = None) -> float:
         """Return the number of seconds to wait before a request for this scope

tests/test_engine.py

@@ -673,6 +673,7 @@ class TestEngineThrottling:
         engine.unpause()
         assert engine.paused is False
 
+    @pytest.mark.requires_reactor  # call_later() needs a reactor or asyncio loop
     def test_maybe_arm_throttling_wakeup_arms_timer(self, engine):
         scheduler = Mock()
         scheduler.has_pending_requests.return_value = True

tests/test_throttling.py

@@ -816,17 +816,6 @@ class TestThrottlingManagerEdges:
         # The still-pending m2 event is discarded from its waiter list.
         assert m2._slot_waiters == []
 
-    def test_scope_manager_protocol_defaults(self):
-        from scrapy.throttling import ThrottlingScopeManagerProtocol  # noqa: PLC0415
-
-        class _Concrete(ThrottlingScopeManagerProtocol):
-            pass
-
-        crawler = get_crawler()
-        # The protocol's default from_crawler()/__init__ are usable as-is.
-        instance = _Concrete.from_crawler(crawler, {"id": "example.com"})
-        assert isinstance(instance, _Concrete)
-
     @coroutine_test
     async def test_process_exception_applies_backoff(self):
         manager = _manager()