Add test for whereis + send integration

Test that looks up a registered process using erlang.whereis()
and then sends a message to it using erlang.send().

Author: benoitc

test/py_pid_send_SUITE.erl

@@ -44,7 +44,8 @@
     test_whereis_nonexistent/1,
     test_whereis_with_atom/1,
     test_whereis_with_bytes/1,
-    test_whereis_invalid_type/1
+    test_whereis_invalid_type/1,
+    test_whereis_and_send/1
 ]).
 
 all() ->
@@ -75,7 +76,8 @@ all() ->
         test_whereis_nonexistent,
         test_whereis_with_atom,
         test_whereis_with_bytes,
-        test_whereis_invalid_type
+        test_whereis_invalid_type,
+        test_whereis_and_send
     ].
 
 init_per_suite(Config) ->
@@ -346,6 +348,25 @@ test_whereis_invalid_type(_Config) ->
     {error, {'TypeError', _}} = py:eval(<<"erlang.whereis(123)">>),
     ok.
 
+%% @doc Test looking up a process with whereis and sending a message to it.
+test_whereis_and_send(_Config) ->
+    Self = self(),
+    erlang:register(py_whereis_send_test, Self),
+    try
+        %% Use Python helper to look up process and send message
+        {ok, true} = py:call(py_test_pid_send, whereis_and_send,
+                              [<<"py_whereis_send_test">>, {<<"hello_from_whereis">>, 42}]),
+        %% Verify we received the message
+        receive
+            {<<"hello_from_whereis">>, 42} -> ok
+        after 5000 ->
+            ct:fail(timeout_waiting_for_message)
+        end
+    after
+        erlang:unregister(py_whereis_send_test)
+    end,
+    ok.
+
 %%% ============================================================================
 %%% Helper Functions
 %%% ============================================================================

test/py_test_pid_send.py

@@ -183,3 +183,15 @@ async def async_interleaved():
         return loop.run_until_complete(async_interleaved())
     finally:
         loop.close()
+
+
+def whereis_and_send(name, msg):
+    """Look up a registered process by name and send it a message.
+
+    Returns True if the process was found and message sent, False otherwise.
+    """
+    pid = erlang.whereis(name)
+    if pid is not None:
+        erlang.send(pid, msg)
+        return True
+    return False