[lldb/test] Update lldbutil.fetch_next_event to match broadcaster class

[mib]

Summary

[lldb/test] Update lldbutil.fetch_next_event to match broadcaster class

This patch updates the lldbutil.fetch_next_event helper function to
either match a specific broadcaster or match a whole broadcaster class.

This is very handy when testing process events for interactive scripted
process debugging.

This also fixes a bug in the failing case, where SBEvent.GetDescription
expects a SBStream argument. We never took that code path in the
original implementation so we didn't hit that bug.

Signed-off-by: Med Ismail Bennani <[e-mail]>

[bulbazord]

lldb/packages/Python/lldbsuite/test/lldbutil.py

1206–1208

Maybe update the docstring to reflect this new parameter? Something like If match_class is true, the provided broadcaster will be matched by class rather than instance?

1220–1221

I'm not sure why you added this part? Is there something not great about calling SBEvent::GetDescription directly?

[mib]

Address @bulbazord comments.

lldb/packages/Python/lldbsuite/test/lldbutil.py

1220–1221

This is actually a fix of the original implementation (SBEvent::GetDescription requires a SBStream argument but when added this helper function, we never took this code path, so we never hit that error).

[bulbazord]

LGTM

lldb/packages/Python/lldbsuite/test/lldbutil.py

 
 def start_listening_from(broadcaster, event_mask):
     """Creates a listener for a specific event mask and add it to the source broadcaster."""
 
     listener = lldb.SBListener("lldb.test.listener")
     broadcaster.AddListener(listener, event_mask)
     return listener
 
-def fetch_next_event(test, listener, broadcaster, timeout=10):
+def fetch_next_event(test, listener, broadcaster, match_class=False, timeout=10):
     """Fetch one event from the listener and return it if it matches the provided broadcaster.
+    If `match_class` is set to True, this will match an event with an entire broadcaster class.
     Fails otherwise."""
 
     event = lldb.SBEvent()
 
     if listener.WaitForEvent(timeout, event):
+        if match_class:
+            if event.GetBroadcasterClass() == broadcaster:
+                return event
+        else:
             if event.BroadcasterMatchesRef(broadcaster):
                 return event
 
+        stream = lldb.SBStream()
+        event.GetDescription(stream)
         test.fail("received event '%s' from unexpected broadcaster '%s'." %
-                  (event.GetDescription(), event.GetBroadcaster().GetName()))
+                  (stream.GetData(), event.GetBroadcaster().GetName()))
 
     test.fail("couldn't fetch an event before reaching the timeout.")
 
 
 # ===================================
 # Utility functions related to Frames
 # ===================================