Additional information in case of error

tests/_event_utils.py

@@ -46,10 +46,10 @@ def events(self) -> List[TEvent]:
     def wait_for_events(self, count=1, timeout=10.0) -> None:
         """Waits for the specified number of events."""
         timeout_time = time.monotonic() + timeout
-        for _ in range(count):
+        for i in range(count):
             remaining_time = max(0.0, timeout_time - time.monotonic())
             if not self._event_semaphore.acquire(timeout=remaining_time):
-                raise TimeoutError("Event observer did not observe the expected number of events.")
+                raise TimeoutError(f"Event observer did not observe the expected number of events. {i}/{count} events")
 
     def _invoke_side_effect(self) -> None:
         if isinstance(self._side_effect, BaseException):