diff --git a/caldav/config.py b/caldav/config.py
index d0008506..05c8af72 100644
--- a/caldav/config.py
+++ b/caldav/config.py
@@ -112,9 +112,13 @@ def read_config(fn, interactive_error=False):
                     f"config file {fn} is not valid JSON, and pyyaml is not installed"
                 ) from None
 
-    except FileNotFoundError:
-        ## File not found
-        logging.debug(f"config file {fn} not found")
+    except OSError as e:
+        ## Optional config file is unusable (missing, a directory, no
+        ## permission, ...).  Treat any of these as "no config here" rather
+        ## than letting e.g. IsADirectoryError propagate out of an optional
+        ## config-file probe (happens when HOME is unset and the path expands
+        ## to something like '//.config//caldav/calendar.conf').
+        logging.debug(f"config file {fn} not usable: {e}")
         return {}
     except ValueError:
         # Re-raise ValueError so caller can handle config errors
diff --git a/caldav/testing.py b/caldav/testing.py
index 28a552d8..1211f30b 100644
--- a/caldav/testing.py
+++ b/caldav/testing.py
@@ -213,18 +213,24 @@ def stop(self) -> None:
 
         if self.xapp_loop and self.xapp_runner:
 
-            async def cleanup_and_stop() -> None:
+            async def cleanup() -> None:
                 await self.xapp_runner.cleanup()
-                self.xapp_loop.stop()
 
             try:
-                asyncio.run_coroutine_threadsafe(cleanup_and_stop(), self.xapp_loop).result(
-                    timeout=10
-                )
+                asyncio.run_coroutine_threadsafe(cleanup(), self.xapp_loop).result(timeout=10)
             except Exception:
-                if self.xapp_loop:
-                    self.xapp_loop.call_soon_threadsafe(self.xapp_loop.stop)
-        elif self.xapp_loop:
+                # Best-effort cleanup: we swallow anything it raises (timeout,
+                # CancelledError, aiohttp errors).  The Xandikos server is
+                # ephemeral per test against a throwaway serverdir, so there is
+                # no shared state to release and nothing to recover here.
+                pass
+
+        # Stop the loop from *outside* any coroutine running on it.  Calling
+        # loop.stop() from within a coroutine scheduled via
+        # run_coroutine_threadsafe can stop the loop before it delivers that
+        # coroutine's result to the concurrent.futures.Future, so .result()
+        # would block until its timeout (~10s) on every single stop().
+        if self.xapp_loop:
             self.xapp_loop.call_soon_threadsafe(self.xapp_loop.stop)
 
         if self.thread:
diff --git a/tests/test_async_integration.py b/tests/test_async_integration.py
index 97565781..ce1c10aa 100644
--- a/tests/test_async_integration.py
+++ b/tests/test_async_integration.py
@@ -186,9 +186,15 @@ def check_compatibility_flag(self, flag: str) -> bool:
         return flag in getattr(self._features, "_old_flags", [])
 
     @pytest.fixture(scope="class")
-    def test_server(self) -> TestServer:
-        """Get the test server for this class."""
-        server = self.server
+    @classmethod
+    def test_server(cls) -> TestServer:
+        """Get the test server for this class.
+
+        Defined as a classmethod because pytest deprecates class-scoped
+        fixtures written as plain instance methods (each test gets a fresh
+        instance, so per-instance state set here would not be visible anyway).
+        """
+        server = cls.server
         server.start()
         yield server
         # Stop the server to free the port for other test modules