Add some more explaination to the docstring
@@ -157,7 +157,15 @@ class ExecutionObserver:
is initialized per thread, so there is no need to clear any pre-existing data
(because there is none), as every thread gets its own instance.
- For more details, look at some implementations, e.g., AssertionTraceObserver
+ Methods that are called from within the thread are not allowed to interact with the
+ 'outside'. The only thing that should leave an observer are results when they are
+ written to the execution result in
+ ExecutionObserver::after_test_case_execution_inside_thread.
+
+ You may interact with the 'outside' in
+ ExecutionObserver::after_test_case_execution_outside_thread.
+
+ For more details, look at some implementations, e.g., AssertionTraceObserver.
"""
@abstractmethod
