Fix resolver garbage collection during pending queries (#211)

Author: bdraco

aiodns/__init__.py

@@ -128,9 +128,8 @@ def nameservers(self) -> Sequence[str]:
     def nameservers(self, value: Iterable[Union[str, bytes]]) -> None:
         self._channel.servers = value
 
-    @staticmethod
     def _callback(
-        fut: asyncio.Future[_T], result: _T, errorno: Optional[int]
+        self, fut: asyncio.Future[_T], result: _T, errorno: Optional[int]
     ) -> None:
         if fut.cancelled():
             return

tests/test_aiodns.py

@@ -823,5 +823,31 @@ async def mock_close() -> None:
     assert close_count == 2
 
 
+@pytest.mark.asyncio
+async def test_temporary_resolver_not_garbage_collected() -> None:
+    """Test temporary resolver is not garbage collected before query completes.
+
+    Regression test for https://github.com/aio-libs/aiodns/issues/209
+
+    When calling query() on a temporary resolver (not stored in a variable),
+    the resolver should not be garbage collected before the query completes.
+    Previously, the callback was a @staticmethod which didn't hold a reference
+    to self, causing the resolver to be garbage collected and the query
+    cancelled.
+    """
+    # Force garbage collection to ensure any weak references are cleared
+    gc.collect()
+
+    # This pattern previously failed with DNSError(24, 'DNS query cancelled')
+    # because the resolver was garbage collected before the query completed
+    result = await aiodns.DNSResolver(nameservers=['8.8.8.8']).query(
+        'google.com', 'A'
+    )
+
+    # Query should succeed
+    assert result
+    assert len(result) > 0
+
+
 if __name__ == '__main__':  # pragma: no cover
     unittest.main(verbosity=2)