Address issues caught by tests

scrapy/utils/_signal_registry.py

@@ -97,8 +97,6 @@ def _accepted(receiver: TypingAny) -> frozenset[str] | None:
         return _accepted_args[key]
     except KeyError:
         pass
-    except TypeError:
-        return _introspect(receiver)
     names = _introspect(receiver)
     _accepted_args[key] = names
     return names
@@ -192,10 +190,7 @@ def _positional_names(receiver: TypingAny, count: int) -> frozenset[str]:
     """Return the names of the first *count* parameters of *receiver*, which
     positional arguments bind and keyword arguments therefore must not repeat.
     """
-    try:
-        parameters = list(inspect.signature(receiver).parameters.values())
-    except (TypeError, ValueError):
-        return frozenset()
+    parameters = list(inspect.signature(receiver).parameters.values())
     return frozenset(
         p.name
         for p in parameters[:count]

tests/test_extension_statsmailer.py

@@ -5,9 +5,9 @@ import pytest
 
 from scrapy import signals
 from scrapy.exceptions import NotConfigured, ScrapyDeprecationWarning
-from scrapy.signalmanager import SignalManager
 from scrapy.statscollectors import StatsCollector
 from scrapy.utils.spider import DefaultSpider
+from scrapy.utils.test import get_crawler
 
 with warnings.catch_warnings():
     warnings.filterwarnings(
@@ -46,11 +46,8 @@ def test_from_crawler_without_recipients_raises_notconfigured():
         statsmailer.StatsMailer.from_crawler(crawler)
 
 
-def test_from_crawler_with_recipients_initializes_extension(dummy_stats, monkeypatch):
-    crawler = MagicMock()
-    crawler.settings.getlist.return_value = ["test@example.com"]
-    crawler.stats = dummy_stats
-    crawler.signals = SignalManager(crawler)
+def test_from_crawler_with_recipients_initializes_extension(monkeypatch):
+    crawler = get_crawler(settings_dict={"STATSMAILER_RCPTS": ["test@example.com"]})
 
     mailer = MagicMock(spec=MailSender)
     monkeypatch.setattr(statsmailer.MailSender, "from_crawler", lambda _: mailer)
@@ -62,21 +59,18 @@ def test_from_crawler_with_recipients_initializes_extension(dummy_stats, monkeyp
     assert ext.mail is mailer
 
 
-def test_from_crawler_connects_spider_closed_signal(dummy_stats, monkeypatch):
-    crawler = MagicMock()
-    crawler.settings.getlist.return_value = ["test@example.com"]
-    crawler.stats = dummy_stats
-    crawler.signals = SignalManager(crawler)
+def test_from_crawler_connects_spider_closed_signal(monkeypatch):
+    crawler = get_crawler(settings_dict={"STATSMAILER_RCPTS": ["test@example.com"]})
 
     mailer = MagicMock(spec=MailSender)
     monkeypatch.setattr(statsmailer.MailSender, "from_crawler", lambda _: mailer)
 
-    statsmailer.StatsMailer.from_crawler(crawler)
+    ext = statsmailer.StatsMailer.from_crawler(crawler)
 
-    connected = crawler.signals.send_catch_log(
+    crawler.signals.send_catch_log(
         signals.spider_closed, spider=DefaultSpider(name="dummy")
     )
-    assert connected is not None
+    assert ext.mail.send.call_count == 1
 
 
 def test_spider_closed_sends_email(dummy_stats):

tests/test_utils_signal_registry.py

@@ -11,6 +11,7 @@ import pytest
 from scrapy import signals
 from scrapy.signalmanager import SignalManager
 from scrapy.utils import _signal_registry as registry
+from scrapy.utils.signal import send_catch_log
 
 if TYPE_CHECKING:
     from collections.abc import Callable
@@ -67,6 +68,21 @@ class TestArgumentDelivery:
         sm.send_catch_log(signal, spider="SPIDER")
         assert received == {"spider": "p-SPIDER"}
 
+    def test_handler_that_cannot_be_introspected_gets_every_argument(self) -> None:
+        assert registry.apply(dict, spider="SPIDER") == {"spider": "SPIDER"}
+
+    def test_positional_arguments_are_not_repeated_as_keywords(self) -> None:
+        received: dict[str, Any] = {}
+
+        def handler(spider: Any, signal: Any = None) -> None:
+            received.update(spider=spider, signal=signal)
+
+        signal = object()
+        sender = object()
+        registry.connect(handler, signal, sender=sender)
+        send_catch_log(signal, sender, "SPIDER")
+        assert received == {"spider": "SPIDER", "signal": signal}
+
     def test_callable_object_handler(self) -> None:
         class Handler:
             def __init__(self) -> None:
@@ -185,6 +201,10 @@ class TestUnknownArgumentWarning:
         with pytest.warns(UserWarning, match=r"scrapy\.signals\.spider_opened"):
             sm.connect(handler, signals.spider_opened)
 
+    def test_warning_falls_back_to_the_repr_of_the_signal(self) -> None:
+        signal = object()
+        assert registry._signal_name(signal) == repr(signal)
+
     def test_lists_every_unknown_argument(self) -> None:
         def handler(cheese: Any = None, ham: Any = None) -> None:
             pass
@@ -243,6 +263,24 @@ class TestReceiverCache:
         assert registry.receivers(signal, sm.sender) == []
 
 
+class TestSignalStorage:
+    def test_signal_that_can_be_weakly_referenced_is_not_kept_alive(self) -> None:
+        class Signal:
+            pass
+
+        def handler(**kwargs: Any) -> None:
+            pass
+
+        signal = Signal()
+        ref = weakref.ref(signal)
+        sm = SignalManager(object())
+        sm.connect(handler, signal)
+        sm.send_catch_log(signal)
+        del signal
+        gc.collect()
+        assert ref() is None
+
+
 class TestMutationDuringDispatch:
     def test_handler_can_disconnect_itself(self) -> None:
         calls: list[str] = []